ELECTRON EMISSION INDUCED BY H+ IONS SCATTERED OFF LiF (100) SURFACES.

L. F. DE FERRARIIS, O. GRIZZI, V.H. PONCE AND E.A. SÁNCHEZ

Rosario, Argentina

Conferencia; XXIV International Conference on Photonic, Electronic and Atomic Collisions; 2005

The energy distributions of electrons emitted near the emerging direction of the pro-jectiles present a pronounced structure centered around ECE = (m/M) EP, where m and M are the electron and projectile masses and EP the ion energy. In ion-atom [1] and beam-foil experi-ments [2] this structure is cusp-shaped, centered at ECE and comes from electrons captured or lost to the continuum state of the outgoing ion Coulomb field. A similar structure has also been observed in grazing ion-surface colli-sions3, that we will refer for simplicity as con-voy electrons (CE), like in beam foil experi-ments. For flat metal and semiconductor sur-faces the CE structure appears shifted toward high velocities [3]. This result was interpreted as a rainbow scattering of electrons in the dy-namically screened field of the ion [4], or more simply as due to the accelerating effect of the induced surface potentials on the electrons cap-tured to the continuum states of the outgoing ion [5,6]. More recently, the CE shift was re-produced by a quantum calculation [7] of the electron loss to the continuum states, i.e., the solutions of the system formed by an hydrogen ion placed in front of a metallic surface (surface distorted continuum wave functions [8]) For insulators, it was reported a shift of the CE distribution toward lower energies, which was interpreted as the deceleration of the outgoing electrons by the potential formed by the track; i.e. the ionized surface atoms left along the surface trajectory of the incoming ion [9]. Very recently, experimental results ob-tained in AlF3 [10] thin films grown on Al sur-faces show that the position of the CE distribu-tion depends on the film thickness, presenting shifts towards both higher and lower energies. In this presentation we will discuss the results of measuring the secondary electron distributions and the CE emission along the specular direction for a LiF(100) surface bom-barded by H+ ions at grazing incidence angles as a function of beam energy, incidence and observation angles, sample crystallographic orientation, temperature and topography. The experimental results show: i) steady spectra in presence of a macroscopic surface charge, ii) shifts of the CE peak posi-tion with temperature, iii) changes in the CE peak position with the sample flattening proc-ess, iv) an increase of the CE yield for decreas-ing sample temperatures, v) a dependence of the CE emission with the crystallographic di-rection, and vi) a vanishing CE peak intensity for H+ energies lower than 20 keV. References [1] C. B. Crooks and M. E. Rudd; Phys. Rev. Lett. 25 (1970) 1599. [2] K. G. Harrison and M. W. Lucas; Phys. Lett. 33A (1970) 142. [3] G. R. Gómez, E. A. Sánchez, O. Grizzi, M.L. Martiarena and V.H. Ponce; Nucl. In-strum. and Meth. B 122 (1997) 171. [4] C. Reinhold and J. Burgdörfer, K. Kimura and M. Mannami; Phy. Rev. Lett. 73 (1994) 2508 [5] T. Iitaka, Y.H. Ohtuki, A. Koyama and H. Ishikawa; Phys. Rev. Lett. 65 (1990) 3160. [6] M.S. Gravielle, J.E. Miraglia, G.G. Otero E.A. Sánchez and O. Grizzi, Phys. Rev. A 69, 042902 (2004). [7] M.L. Martiarena, Nucl. Instrum. and Meth. B, (2005), accepted for publication. [8] M.L. Martiarena and V.H. Ponce, J. of Phys. B: At. Mol. Opt. Phys. 36, 2991-3007 (2003). [9] G.R. Gómez, O. Grizzi, E.A. Sánchez and V.H. Ponce; Phys. Rev. B 58 (1998) 7403. [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). References [1] C. B. Crooks and M. E. Rudd; Phys. Rev. Lett. 25 (1970) 1599. [2] K. G. Harrison and M. W. Lucas; Phys. Lett. 33A (1970) 142. [3] G. R. Gómez, E. A. Sánchez, O. Grizzi, M.L. Martiarena and V.H. Ponce; Nucl. In-strum. and Meth. B 122 (1997) 171. [4] C. Reinhold and J. Burgdörfer, K. Kimura and M. Mannami; Phy. Rev. Lett. 73 (1994) 2508 [5] T. Iitaka, Y.H. Ohtuki, A. Koyama and H. Ishikawa; Phys. Rev. Lett. 65 (1990) 3160. [6] M.S. Gravielle, J.E. Miraglia, G.G. Otero E.A. Sánchez and O. Grizzi, Phys. Rev. A 69, 042902 (2004). [7] M.L. Martiarena, Nucl. Instrum. and Meth. B, (2005), accepted for publication. [8] M.L. Martiarena and V.H. Ponce, J. of Phys. B: At. Mol. Opt. Phys. 36, 2991-3007 (2003). [9] G.R. Gómez, O. Grizzi, E.A. Sánchez and V.H. Ponce; Phys. Rev. B 58 (1998) 7403. [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). The experimental results show: i) steady spectra in presence of a macroscopic surface charge, ii) shifts of the CE peak posi-tion with temperature, iii) changes in the CE peak position with the sample flattening proc-ess, iv) an increase of the CE yield for decreas-ing sample temperatures, v) a dependence of the CE emission with the crystallographic di-rection, and vi) a vanishing CE peak intensity for H+ energies lower than 20 keV. References [1] C. B. Crooks and M. E. Rudd; Phys. Rev. Lett. 25 (1970) 1599. [2] K. G. Harrison and M. W. Lucas; Phys. Lett. 33A (1970) 142. [3] G. R. Gómez, E. A. Sánchez, O. Grizzi, M.L. Martiarena and V.H. Ponce; Nucl. In-strum. and Meth. B 122 (1997) 171. [4] C. Reinhold and J. Burgdörfer, K. Kimura and M. Mannami; Phy. Rev. Lett. 73 (1994) 2508 [5] T. Iitaka, Y.H. Ohtuki, A. Koyama and H. Ishikawa; Phys. Rev. Lett. 65 (1990) 3160. [6] M.S. Gravielle, J.E. Miraglia, G.G. Otero E.A. Sánchez and O. Grizzi, Phys. Rev. A 69, 042902 (2004). [7] M.L. Martiarena, Nucl. Instrum. and Meth. B, (2005), accepted for publication. [8] M.L. Martiarena and V.H. Ponce, J. of Phys. B: At. Mol. Opt. Phys. 36, 2991-3007 (2003). [9] G.R. Gómez, O. Grizzi, E.A. Sánchez and V.H. Ponce; Phys. Rev. B 58 (1998) 7403. [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). References [1] C. B. Crooks and M. E. Rudd; Phys. Rev. Lett. 25 (1970) 1599. [2] K. G. Harrison and M. W. Lucas; Phys. Lett. 33A (1970) 142. [3] G. R. Gómez, E. A. Sánchez, O. Grizzi, M.L. Martiarena and V.H. Ponce; Nucl. In-strum. and Meth. B 122 (1997) 171. [4] C. Reinhold and J. Burgdörfer, K. Kimura and M. Mannami; Phy. Rev. Lett. 73 (1994) 2508 [5] T. Iitaka, Y.H. Ohtuki, A. Koyama and H. Ishikawa; Phys. Rev. Lett. 65 (1990) 3160. [6] M.S. Gravielle, J.E. Miraglia, G.G. Otero E.A. Sánchez and O. Grizzi, Phys. Rev. A 69, 042902 (2004). [7] M.L. Martiarena, Nucl. Instrum. and Meth. B, (2005), accepted for publication. [8] M.L. Martiarena and V.H. Ponce, J. of Phys. B: At. Mol. Opt. Phys. 36, 2991-3007 (2003). [9] G.R. Gómez, O. Grizzi, E.A. Sánchez and V.H. Ponce; Phys. Rev. B 58 (1998) 7403. [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). In this presentation we will discuss the results of measuring the secondary electron distributions and the CE emission along the specular direction for a LiF(100) surface bom-barded by H+ ions at grazing incidence angles as a function of beam energy, incidence and observation angles, sample crystallographic orientation, temperature and topography. The experimental results show: i) steady spectra in presence of a macroscopic surface charge, ii) shifts of the CE peak posi-tion with temperature, iii) changes in the CE peak position with the sample flattening proc-ess, iv) an increase of the CE yield for decreas-ing sample temperatures, v) a dependence of the CE emission with the crystallographic di-rection, and vi) a vanishing CE peak intensity for H+ energies lower than 20 keV. References [1] C. B. Crooks and M. E. Rudd; Phys. Rev. Lett. 25 (1970) 1599. [2] K. G. Harrison and M. W. Lucas; Phys. Lett. 33A (1970) 142. [3] G. R. Gómez, E. A. Sánchez, O. Grizzi, M.L. Martiarena and V.H. Ponce; Nucl. In-strum. and Meth. B 122 (1997) 171. [4] C. Reinhold and J. Burgdörfer, K. Kimura and M. Mannami; Phy. Rev. Lett. 73 (1994) 2508 [5] T. Iitaka, Y.H. Ohtuki, A. Koyama and H. Ishikawa; Phys. Rev. Lett. 65 (1990) 3160. [6] M.S. Gravielle, J.E. Miraglia, G.G. Otero E.A. Sánchez and O. Grizzi, Phys. Rev. A 69, 042902 (2004). [7] M.L. Martiarena, Nucl. Instrum. and Meth. B, (2005), accepted for publication. [8] M.L. Martiarena and V.H. Ponce, J. of Phys. B: At. Mol. Opt. Phys. 36, 2991-3007 (2003). [9] G.R. Gómez, O. Grizzi, E.A. Sánchez and V.H. Ponce; Phys. Rev. B 58 (1998) 7403. [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). References [1] C. B. Crooks and M. E. Rudd; Phys. Rev. Lett. 25 (1970) 1599. [2] K. G. Harrison and M. W. Lucas; Phys. Lett. 33A (1970) 142. [3] G. R. Gómez, E. A. Sánchez, O. Grizzi, M.L. Martiarena and V.H. Ponce; Nucl. In-strum. and Meth. B 122 (1997) 171. [4] C. Reinhold and J. Burgdörfer, K. Kimura and M. Mannami; Phy. Rev. Lett. 73 (1994) 2508 [5] T. Iitaka, Y.H. Ohtuki, A. Koyama and H. Ishikawa; Phys. Rev. Lett. 65 (1990) 3160. [6] M.S. Gravielle, J.E. Miraglia, G.G. Otero E.A. Sánchez and O. Grizzi, Phys. Rev. A 69, 042902 (2004). [7] M.L. Martiarena, Nucl. Instrum. and Meth. B, (2005), accepted for publication. [8] M.L. Martiarena and V.H. Ponce, J. of Phys. B: At. Mol. Opt. Phys. 36, 2991-3007 (2003). [9] G.R. Gómez, O. Grizzi, E.A. Sánchez and V.H. Ponce; Phys. Rev. B 58 (1998) 7403. [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). The experimental results show: i) steady spectra in presence of a macroscopic surface charge, ii) shifts of the CE peak posi-tion with temperature, iii) changes in the CE peak position with the sample flattening proc-ess, iv) an increase of the CE yield for decreas-ing sample temperatures, v) a dependence of the CE emission with the crystallographic di-rection, and vi) a vanishing CE peak intensity for H+ energies lower than 20 keV. References [1] C. B. Crooks and M. E. Rudd; Phys. Rev. Lett. 25 (1970) 1599. [2] K. G. Harrison and M. W. Lucas; Phys. Lett. 33A (1970) 142. [3] G. R. Gómez, E. A. Sánchez, O. Grizzi, M.L. Martiarena and V.H. Ponce; Nucl. In-strum. and Meth. B 122 (1997) 171. [4] C. Reinhold and J. Burgdörfer, K. Kimura and M. Mannami; Phy. Rev. Lett. 73 (1994) 2508 [5] T. Iitaka, Y.H. Ohtuki, A. Koyama and H. Ishikawa; Phys. Rev. Lett. 65 (1990) 3160. [6] M.S. Gravielle, J.E. Miraglia, G.G. Otero E.A. Sánchez and O. Grizzi, Phys. Rev. A 69, 042902 (2004). [7] M.L. Martiarena, Nucl. Instrum. and Meth. B, (2005), accepted for publication. [8] M.L. Martiarena and V.H. Ponce, J. of Phys. B: At. Mol. Opt. Phys. 36, 2991-3007 (2003). [9] G.R. Gómez, O. Grizzi, E.A. Sánchez and V.H. Ponce; Phys. Rev. B 58 (1998) 7403. [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). References [1] C. B. Crooks and M. E. Rudd; Phys. Rev. Lett. 25 (1970) 1599. [2] K. G. Harrison and M. W. Lucas; Phys. Lett. 33A (1970) 142. [3] G. R. Gómez, E. A. Sánchez, O. Grizzi, M.L. Martiarena and V.H. Ponce; Nucl. In-strum. and Meth. B 122 (1997) 171. [4] C. Reinhold and J. Burgdörfer, K. Kimura and M. Mannami; Phy. Rev. Lett. 73 (1994) 2508 [5] T. Iitaka, Y.H. Ohtuki, A. Koyama and H. Ishikawa; Phys. Rev. Lett. 65 (1990) 3160. [6] M.S. Gravielle, J.E. Miraglia, G.G. Otero E.A. Sánchez and O. Grizzi, Phys. Rev. A 69, 042902 (2004). [7] M.L. Martiarena, Nucl. Instrum. and Meth. B, (2005), accepted for publication. [8] M.L. Martiarena and V.H. Ponce, J. of Phys. B: At. Mol. Opt. Phys. 36, 2991-3007 (2003). [9] G.R. Gómez, O. Grizzi, E.A. Sánchez and V.H. Ponce; Phys. Rev. B 58 (1998) 7403. [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). For insulators, it was reported a shift of the CE distribution toward lower energies, which was interpreted as the deceleration of the outgoing electrons by the potential formed by the track; i.e. the ionized surface atoms left along the surface trajectory of the incoming ion [9]. Very recently, experimental results ob-tained in AlF3 [10] thin films grown on Al sur-faces show that the position of the CE distribu-tion depends on the film thickness, presenting shifts towards both higher and lower energies. In this presentation we will discuss the results of measuring the secondary electron distributions and the CE emission along the specular direction for a LiF(100) surface bom-barded by H+ ions at grazing incidence angles as a function of beam energy, incidence and observation angles, sample crystallographic orientation, temperature and topography. The experimental results show: i) steady spectra in presence of a macroscopic surface charge, ii) shifts of the CE peak posi-tion with temperature, iii) changes in the CE peak position with the sample flattening proc-ess, iv) an increase of the CE yield for decreas-ing sample temperatures, v) a dependence of the CE emission with the crystallographic di-rection, and vi) a vanishing CE peak intensity for H+ energies lower than 20 keV. References [1] C. B. Crooks and M. E. Rudd; Phys. Rev. Lett. 25 (1970) 1599. [2] K. G. Harrison and M. W. Lucas; Phys. Lett. 33A (1970) 142. [3] G. R. Gómez, E. A. Sánchez, O. Grizzi, M.L. Martiarena and V.H. Ponce; Nucl. In-strum. and Meth. B 122 (1997) 171. [4] C. Reinhold and J. Burgdörfer, K. Kimura and M. Mannami; Phy. Rev. Lett. 73 (1994) 2508 [5] T. Iitaka, Y.H. Ohtuki, A. Koyama and H. Ishikawa; Phys. Rev. Lett. 65 (1990) 3160. [6] M.S. Gravielle, J.E. Miraglia, G.G. Otero E.A. Sánchez and O. Grizzi, Phys. Rev. A 69, 042902 (2004). [7] M.L. Martiarena, Nucl. Instrum. and Meth. B, (2005), accepted for publication. [8] M.L. Martiarena and V.H. Ponce, J. of Phys. B: At. Mol. Opt. Phys. 36, 2991-3007 (2003). [9] G.R. Gómez, O. Grizzi, E.A. Sánchez and V.H. Ponce; Phys. Rev. B 58 (1998) 7403. [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). References [1] C. B. Crooks and M. E. Rudd; Phys. Rev. Lett. 25 (1970) 1599. [2] K. G. Harrison and M. W. Lucas; Phys. Lett. 33A (1970) 142. [3] G. R. Gómez, E. A. Sánchez, O. Grizzi, M.L. Martiarena and V.H. Ponce; Nucl. In-strum. and Meth. B 122 (1997) 171. [4] C. Reinhold and J. Burgdörfer, K. Kimura and M. Mannami; Phy. Rev. Lett. 73 (1994) 2508 [5] T. Iitaka, Y.H. Ohtuki, A. Koyama and H. Ishikawa; Phys. Rev. Lett. 65 (1990) 3160. [6] M.S. Gravielle, J.E. Miraglia, G.G. Otero E.A. Sánchez and O. Grizzi, Phys. Rev. A 69, 042902 (2004). [7] M.L. Martiarena, Nucl. Instrum. and Meth. B, (2005), accepted for publication. [8] M.L. Martiarena and V.H. Ponce, J. of Phys. B: At. Mol. Opt. Phys. 36, 2991-3007 (2003). [9] G.R. Gómez, O. Grizzi, E.A. Sánchez and V.H. Ponce; Phys. Rev. B 58 (1998) 7403. [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). The experimental results show: i) steady spectra in presence of a macroscopic surface charge, ii) shifts of the CE peak posi-tion with temperature, iii) changes in the CE peak position with the sample flattening proc-ess, iv) an increase of the CE yield for decreas-ing sample temperatures, v) a dependence of the CE emission with the crystallographic di-rection, and vi) a vanishing CE peak intensity for H+ energies lower than 20 keV. References [1] C. B. Crooks and M. E. Rudd; Phys. Rev. Lett. 25 (1970) 1599. [2] K. G. Harrison and M. W. Lucas; Phys. Lett. 33A (1970) 142. [3] G. R. Gómez, E. A. Sánchez, O. Grizzi, M.L. Martiarena and V.H. Ponce; Nucl. In-strum. and Meth. B 122 (1997) 171. [4] C. Reinhold and J. Burgdörfer, K. Kimura and M. Mannami; Phy. Rev. Lett. 73 (1994) 2508 [5] T. Iitaka, Y.H. Ohtuki, A. Koyama and H. Ishikawa; Phys. Rev. Lett. 65 (1990) 3160. [6] M.S. Gravielle, J.E. Miraglia, G.G. Otero E.A. Sánchez and O. Grizzi, Phys. Rev. A 69, 042902 (2004). [7] M.L. Martiarena, Nucl. Instrum. and Meth. B, (2005), accepted for publication. [8] M.L. Martiarena and V.H. Ponce, J. of Phys. B: At. Mol. Opt. Phys. 36, 2991-3007 (2003). [9] G.R. Gómez, O. Grizzi, E.A. Sánchez and V.H. Ponce; Phys. Rev. B 58 (1998) 7403. [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). References [1] C. B. Crooks and M. E. Rudd; Phys. Rev. Lett. 25 (1970) 1599. [2] K. G. Harrison and M. W. Lucas; Phys. Lett. 33A (1970) 142. [3] G. R. Gómez, E. A. Sánchez, O. Grizzi, M.L. Martiarena and V.H. Ponce; Nucl. In-strum. and Meth. B 122 (1997) 171. [4] C. Reinhold and J. Burgdörfer, K. Kimura and M. Mannami; Phy. Rev. Lett. 73 (1994) 2508 [5] T. Iitaka, Y.H. Ohtuki, A. Koyama and H. Ishikawa; Phys. Rev. Lett. 65 (1990) 3160. [6] M.S. Gravielle, J.E. Miraglia, G.G. Otero E.A. Sánchez and O. Grizzi, Phys. Rev. A 69, 042902 (2004). [7] M.L. Martiarena, Nucl. Instrum. and Meth. B, (2005), accepted for publication. [8] M.L. Martiarena and V.H. Ponce, J. of Phys. B: At. Mol. Opt. Phys. 36, 2991-3007 (2003). [9] G.R. Gómez, O. Grizzi, E.A. Sánchez and V.H. Ponce; Phys. Rev. B 58 (1998) 7403. [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). In this presentation we will discuss the results of measuring the secondary electron distributions and the CE emission along the specular direction for a LiF(100) surface bom-barded by H+ ions at grazing incidence angles as a function of beam energy, incidence and observation angles, sample crystallographic orientation, temperature and topography. The experimental results show: i) steady spectra in presence of a macroscopic surface charge, ii) shifts of the CE peak posi-tion with temperature, iii) changes in the CE peak position with the sample flattening proc-ess, iv) an increase of the CE yield for decreas-ing sample temperatures, v) a dependence of the CE emission with the crystallographic di-rection, and vi) a vanishing CE peak intensity for H+ energies lower than 20 keV. References [1] C. B. Crooks and M. E. Rudd; Phys. Rev. Lett. 25 (1970) 1599. [2] K. G. Harrison and M. W. Lucas; Phys. Lett. 33A (1970) 142. [3] G. R. Gómez, E. A. Sánchez, O. Grizzi, M.L. Martiarena and V.H. Ponce; Nucl. In-strum. and Meth. B 122 (1997) 171. [4] C. Reinhold and J. Burgdörfer, K. Kimura and M. Mannami; Phy. Rev. Lett. 73 (1994) 2508 [5] T. Iitaka, Y.H. Ohtuki, A. Koyama and H. Ishikawa; Phys. Rev. Lett. 65 (1990) 3160. [6] M.S. Gravielle, J.E. Miraglia, G.G. Otero E.A. Sánchez and O. Grizzi, Phys. Rev. A 69, 042902 (2004). [7] M.L. Martiarena, Nucl. Instrum. and Meth. B, (2005), accepted for publication. [8] M.L. Martiarena and V.H. Ponce, J. of Phys. B: At. Mol. Opt. Phys. 36, 2991-3007 (2003). [9] G.R. Gómez, O. Grizzi, E.A. Sánchez and V.H. Ponce; Phys. Rev. B 58 (1998) 7403. [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). References [1] C. B. Crooks and M. E. Rudd; Phys. Rev. Lett. 25 (1970) 1599. [2] K. G. Harrison and M. W. Lucas; Phys. Lett. 33A (1970) 142. [3] G. R. Gómez, E. A. Sánchez, O. Grizzi, M.L. Martiarena and V.H. Ponce; Nucl. In-strum. and Meth. B 122 (1997) 171. [4] C. Reinhold and J. Burgdörfer, K. Kimura and M. Mannami; Phy. Rev. Lett. 73 (1994) 2508 [5] T. Iitaka, Y.H. Ohtuki, A. Koyama and H. Ishikawa; Phys. Rev. Lett. 65 (1990) 3160. [6] M.S. Gravielle, J.E. Miraglia, G.G. Otero E.A. Sánchez and O. Grizzi, Phys. Rev. A 69, 042902 (2004). [7] M.L. Martiarena, Nucl. Instrum. and Meth. B, (2005), accepted for publication. [8] M.L. Martiarena and V.H. Ponce, J. of Phys. B: At. Mol. Opt. Phys. 36, 2991-3007 (2003). [9] G.R. Gómez, O. Grizzi, E.A. Sánchez and V.H. Ponce; Phys. Rev. B 58 (1998) 7403. [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). The experimental results show: i) steady spectra in presence of a macroscopic surface charge, ii) shifts of the CE peak posi-tion with temperature, iii) changes in the CE peak position with the sample flattening proc-ess, iv) an increase of the CE yield for decreas-ing sample temperatures, v) a dependence of the CE emission with the crystallographic di-rection, and vi) a vanishing CE peak intensity for H+ energies lower than 20 keV. References [1] C. B. Crooks and M. E. Rudd; Phys. Rev. Lett. 25 (1970) 1599. [2] K. G. Harrison and M. W. Lucas; Phys. Lett. 33A (1970) 142. [3] G. R. Gómez, E. A. Sánchez, O. Grizzi, M.L. Martiarena and V.H. Ponce; Nucl. In-strum. and Meth. B 122 (1997) 171. [4] C. Reinhold and J. Burgdörfer, K. Kimura and M. Mannami; Phy. Rev. Lett. 73 (1994) 2508 [5] T. Iitaka, Y.H. Ohtuki, A. Koyama and H. Ishikawa; Phys. Rev. Lett. 65 (1990) 3160. [6] M.S. Gravielle, J.E. Miraglia, G.G. Otero E.A. Sánchez and O. Grizzi, Phys. Rev. A 69, 042902 (2004). [7] M.L. Martiarena, Nucl. Instrum. and Meth. B, (2005), accepted for publication. [8] M.L. Martiarena and V.H. Ponce, J. of Phys. B: At. Mol. Opt. Phys. 36, 2991-3007 (2003). [9] G.R. Gómez, O. Grizzi, E.A. Sánchez and V.H. Ponce; Phys. Rev. B 58 (1998) 7403. [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). References [1] C. B. Crooks and M. E. Rudd; Phys. Rev. Lett. 25 (1970) 1599. [2] K. G. Harrison and M. W. Lucas; Phys. Lett. 33A (1970) 142. [3] G. R. Gómez, E. A. Sánchez, O. Grizzi, M.L. Martiarena and V.H. Ponce; Nucl. In-strum. and Meth. B 122 (1997) 171. [4] C. Reinhold and J. Burgdörfer, K. Kimura and M. Mannami; Phy. Rev. Lett. 73 (1994) 2508 [5] T. Iitaka, Y.H. Ohtuki, A. Koyama and H. Ishikawa; Phys. Rev. Lett. 65 (1990) 3160. [6] M.S. Gravielle, J.E. Miraglia, G.G. Otero E.A. Sánchez and O. Grizzi, Phys. Rev. A 69, 042902 (2004). [7] M.L. Martiarena, Nucl. Instrum. and Meth. B, (2005), accepted for publication. [8] M.L. Martiarena and V.H. Ponce, J. of Phys. B: At. Mol. Opt. Phys. 36, 2991-3007 (2003). [9] G.R. Gómez, O. Grizzi, E.A. Sánchez and V.H. Ponce; Phys. Rev. B 58 (1998) 7403. [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). CE = (m/M) EP, where m and M are the electron and projectile masses and EP the ion energy. In ion-atom [1] and beam-foil experi-ments [2] this structure is cusp-shaped, centered at ECE and comes from electrons captured or lost to the continuum state of the outgoing ion Coulomb field. A similar structure has also been observed in grazing ion-surface colli-sions3, that we will refer for simplicity as con-voy electrons (CE), like in beam foil experi-ments. For flat metal and semiconductor sur-faces the CE structure appears shifted toward high velocities [3]. This result was interpreted as a rainbow scattering of electrons in the dy-namically screened field of the ion [4], or more simply as due to the accelerating effect of the induced surface potentials on the electrons cap-tured to the continuum states of the outgoing ion [5,6]. More recently, the CE shift was re-produced by a quantum calculation [7] of the electron loss to the continuum states, i.e., the solutions of the system formed by an hydrogen ion placed in front of a metallic surface (surface distorted continuum wave functions [8]) For insulators, it was reported a shift of the CE distribution toward lower energies, which was interpreted as the deceleration of the outgoing electrons by the potential formed by the track; i.e. the ionized surface atoms left along the surface trajectory of the incoming ion [9]. Very recently, experimental results ob-tained in AlF3 [10] thin films grown on Al sur-faces show that the position of the CE distribu-tion depends on the film thickness, presenting shifts towards both higher and lower energies. In this presentation we will discuss the results of measuring the secondary electron distributions and the CE emission along the specular direction for a LiF(100) surface bom-barded by H+ ions at grazing incidence angles as a function of beam energy, incidence and observation angles, sample crystallographic orientation, temperature and topography. The experimental results show: i) steady spectra in presence of a macroscopic surface charge, ii) shifts of the CE peak posi-tion with temperature, iii) changes in the CE peak position with the sample flattening proc-ess, iv) an increase of the CE yield for decreas-ing sample temperatures, v) a dependence of the CE emission with the crystallographic di-rection, and vi) a vanishing CE peak intensity for H+ energies lower than 20 keV. References [1] C. B. Crooks and M. E. Rudd; Phys. Rev. Lett. 25 (1970) 1599. [2] K. G. Harrison and M. W. Lucas; Phys. Lett. 33A (1970) 142. [3] G. R. Gómez, E. A. Sánchez, O. Grizzi, M.L. Martiarena and V.H. Ponce; Nucl. In-strum. and Meth. B 122 (1997) 171. [4] C. Reinhold and J. Burgdörfer, K. Kimura and M. Mannami; Phy. Rev. Lett. 73 (1994) 2508 [5] T. Iitaka, Y.H. Ohtuki, A. Koyama and H. Ishikawa; Phys. Rev. Lett. 65 (1990) 3160. [6] M.S. Gravielle, J.E. Miraglia, G.G. Otero E.A. Sánchez and O. Grizzi, Phys. Rev. A 69, 042902 (2004). [7] M.L. Martiarena, Nucl. Instrum. and Meth. B, (2005), accepted for publication. [8] M.L. Martiarena and V.H. Ponce, J. of Phys. B: At. Mol. Opt. Phys. 36, 2991-3007 (2003). [9] G.R. Gómez, O. Grizzi, E.A. Sánchez and V.H. Ponce; Phys. Rev. B 58 (1998) 7403. [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). References [1] C. B. Crooks and M. E. Rudd; Phys. Rev. Lett. 25 (1970) 1599. [2] K. G. Harrison and M. W. Lucas; Phys. Lett. 33A (1970) 142. [3] G. R. Gómez, E. A. Sánchez, O. Grizzi, M.L. Martiarena and V.H. Ponce; Nucl. In-strum. and Meth. B 122 (1997) 171. [4] C. Reinhold and J. Burgdörfer, K. Kimura and M. Mannami; Phy. Rev. Lett. 73 (1994) 2508 [5] T. Iitaka, Y.H. Ohtuki, A. Koyama and H. Ishikawa; Phys. Rev. Lett. 65 (1990) 3160. [6] M.S. Gravielle, J.E. Miraglia, G.G. Otero E.A. Sánchez and O. Grizzi, Phys. Rev. A 69, 042902 (2004). [7] M.L. Martiarena, Nucl. Instrum. and Meth. B, (2005), accepted for publication. [8] M.L. Martiarena and V.H. Ponce, J. of Phys. B: At. Mol. Opt. Phys. 36, 2991-3007 (2003). [9] G.R. Gómez, O. Grizzi, E.A. Sánchez and V.H. Ponce; Phys. Rev. B 58 (1998) 7403. [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). The experimental results show: i) steady spectra in presence of a macroscopic surface charge, ii) shifts of the CE peak posi-tion with temperature, iii) changes in the CE peak position with the sample flattening proc-ess, iv) an increase of the CE yield for decreas-ing sample temperatures, v) a dependence of the CE emission with the crystallographic di-rection, and vi) a vanishing CE peak intensity for H+ energies lower than 20 keV. References [1] C. B. Crooks and M. E. Rudd; Phys. Rev. Lett. 25 (1970) 1599. [2] K. G. Harrison and M. W. Lucas; Phys. Lett. 33A (1970) 142. [3] G. R. Gómez, E. A. Sánchez, O. Grizzi, M.L. Martiarena and V.H. Ponce; Nucl. In-strum. and Meth. B 122 (1997) 171. [4] C. Reinhold and J. Burgdörfer, K. Kimura and M. Mannami; Phy. Rev. Lett. 73 (1994) 2508 [5] T. Iitaka, Y.H. Ohtuki, A. Koyama and H. Ishikawa; Phys. Rev. Lett. 65 (1990) 3160. [6] M.S. Gravielle, J.E. Miraglia, G.G. Otero E.A. Sánchez and O. Grizzi, Phys. Rev. A 69, 042902 (2004). [7] M.L. Martiarena, Nucl. Instrum. and Meth. B, (2005), accepted for publication. [8] M.L. Martiarena and V.H. Ponce, J. of Phys. B: At. Mol. Opt. Phys. 36, 2991-3007 (2003). [9] G.R. Gómez, O. Grizzi, E.A. Sánchez and V.H. Ponce; Phys. Rev. B 58 (1998) 7403. [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). References [1] C. B. Crooks and M. E. Rudd; Phys. Rev. Lett. 25 (1970) 1599. [2] K. G. Harrison and M. W. Lucas; Phys. Lett. 33A (1970) 142. [3] G. R. Gómez, E. A. Sánchez, O. Grizzi, M.L. Martiarena and V.H. Ponce; Nucl. In-strum. and Meth. B 122 (1997) 171. [4] C. Reinhold and J. Burgdörfer, K. Kimura and M. Mannami; Phy. Rev. Lett. 73 (1994) 2508 [5] T. Iitaka, Y.H. Ohtuki, A. Koyama and H. Ishikawa; Phys. Rev. Lett. 65 (1990) 3160. [6] M.S. Gravielle, J.E. Miraglia, G.G. Otero E.A. Sánchez and O. Grizzi, Phys. Rev. A 69, 042902 (2004). [7] M.L. Martiarena, Nucl. Instrum. and Meth. B, (2005), accepted for publication. [8] M.L. Martiarena and V.H. Ponce, J. of Phys. B: At. Mol. Opt. Phys. 36, 2991-3007 (2003). [9] G.R. Gómez, O. Grizzi, E.A. Sánchez and V.H. Ponce; Phys. Rev. B 58 (1998) 7403. [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). In this presentation we will discuss the results of measuring the secondary electron distributions and the CE emission along the specular direction for a LiF(100) surface bom-barded by H+ ions at grazing incidence angles as a function of beam energy, incidence and observation angles, sample crystallographic orientation, temperature and topography. The experimental results show: i) steady spectra in presence of a macroscopic surface charge, ii) shifts of the CE peak posi-tion with temperature, iii) changes in the CE peak position with the sample flattening proc-ess, iv) an increase of the CE yield for decreas-ing sample temperatures, v) a dependence of the CE emission with the crystallographic di-rection, and vi) a vanishing CE peak intensity for H+ energies lower than 20 keV. References [1] C. B. Crooks and M. E. Rudd; Phys. Rev. Lett. 25 (1970) 1599. [2] K. G. Harrison and M. W. Lucas; Phys. Lett. 33A (1970) 142. [3] G. R. Gómez, E. A. Sánchez, O. Grizzi, M.L. Martiarena and V.H. Ponce; Nucl. In-strum. and Meth. B 122 (1997) 171. [4] C. Reinhold and J. Burgdörfer, K. Kimura and M. Mannami; Phy. Rev. Lett. 73 (1994) 2508 [5] T. Iitaka, Y.H. Ohtuki, A. Koyama and H. Ishikawa; Phys. Rev. Lett. 65 (1990) 3160. [6] M.S. Gravielle, J.E. Miraglia, G.G. Otero E.A. Sánchez and O. Grizzi, Phys. Rev. A 69, 042902 (2004). [7] M.L. Martiarena, Nucl. Instrum. and Meth. B, (2005), accepted for publication. [8] M.L. Martiarena and V.H. Ponce, J. of Phys. B: At. Mol. Opt. Phys. 36, 2991-3007 (2003). [9] G.R. Gómez, O. Grizzi, E.A. Sánchez and V.H. Ponce; Phys. Rev. B 58 (1998) 7403. [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). References [1] C. B. Crooks and M. E. Rudd; Phys. Rev. Lett. 25 (1970) 1599. [2] K. G. Harrison and M. W. Lucas; Phys. Lett. 33A (1970) 142. [3] G. R. Gómez, E. A. Sánchez, O. Grizzi, M.L. Martiarena and V.H. Ponce; Nucl. In-strum. and Meth. B 122 (1997) 171. [4] C. Reinhold and J. Burgdörfer, K. Kimura and M. Mannami; Phy. Rev. Lett. 73 (1994) 2508 [5] T. Iitaka, Y.H. Ohtuki, A. Koyama and H. Ishikawa; Phys. Rev. Lett. 65 (1990) 3160. [6] M.S. Gravielle, J.E. Miraglia, G.G. Otero E.A. Sánchez and O. Grizzi, Phys. Rev. A 69, 042902 (2004). [7] M.L. Martiarena, Nucl. Instrum. and Meth. B, (2005), accepted for publication. [8] M.L. Martiarena and V.H. Ponce, J. of Phys. B: At. Mol. Opt. Phys. 36, 2991-3007 (2003). [9] G.R. Gómez, O. Grizzi, E.A. Sánchez and V.H. Ponce; Phys. Rev. B 58 (1998) 7403. [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). The experimental results show: i) steady spectra in presence of a macroscopic surface charge, ii) shifts of the CE peak posi-tion with temperature, iii) changes in the CE peak position with the sample flattening proc-ess, iv) an increase of the CE yield for decreas-ing sample temperatures, v) a dependence of the CE emission with the crystallographic di-rection, and vi) a vanishing CE peak intensity for H+ energies lower than 20 keV. References [1] C. B. Crooks and M. E. Rudd; Phys. Rev. Lett. 25 (1970) 1599. [2] K. G. Harrison and M. W. Lucas; Phys. Lett. 33A (1970) 142. [3] G. R. Gómez, E. A. Sánchez, O. Grizzi, M.L. Martiarena and V.H. Ponce; Nucl. In-strum. and Meth. B 122 (1997) 171. [4] C. Reinhold and J. Burgdörfer, K. Kimura and M. Mannami; Phy. Rev. Lett. 73 (1994) 2508 [5] T. Iitaka, Y.H. Ohtuki, A. Koyama and H. Ishikawa; Phys. Rev. Lett. 65 (1990) 3160. [6] M.S. Gravielle, J.E. Miraglia, G.G. Otero E.A. Sánchez and O. Grizzi, Phys. Rev. A 69, 042902 (2004). [7] M.L. Martiarena, Nucl. Instrum. and Meth. B, (2005), accepted for publication. [8] M.L. Martiarena and V.H. Ponce, J. of Phys. B: At. Mol. Opt. Phys. 36, 2991-3007 (2003). [9] G.R. Gómez, O. Grizzi, E.A. Sánchez and V.H. Ponce; Phys. Rev. B 58 (1998) 7403. [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). References [1] C. B. Crooks and M. E. Rudd; Phys. Rev. Lett. 25 (1970) 1599. [2] K. G. Harrison and M. W. Lucas; Phys. Lett. 33A (1970) 142. [3] G. R. Gómez, E. A. Sánchez, O. Grizzi, M.L. Martiarena and V.H. Ponce; Nucl. In-strum. and Meth. B 122 (1997) 171. [4] C. Reinhold and J. Burgdörfer, K. Kimura and M. Mannami; Phy. Rev. Lett. 73 (1994) 2508 [5] T. Iitaka, Y.H. Ohtuki, A. Koyama and H. Ishikawa; Phys. Rev. Lett. 65 (1990) 3160. [6] M.S. Gravielle, J.E. Miraglia, G.G. Otero E.A. Sánchez and O. Grizzi, Phys. Rev. A 69, 042902 (2004). [7] M.L. Martiarena, Nucl. Instrum. and Meth. B, (2005), accepted for publication. [8] M.L. Martiarena and V.H. Ponce, J. of Phys. B: At. Mol. Opt. Phys. 36, 2991-3007 (2003). [9] G.R. Gómez, O. Grizzi, E.A. Sánchez and V.H. Ponce; Phys. Rev. B 58 (1998) 7403. [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). 3 [10] thin films grown on Al sur-faces show that the position of the CE distribu-tion depends on the film thickness, presenting shifts towards both higher and lower energies. In this presentation we will discuss the results of measuring the secondary electron distributions and the CE emission along the specular direction for a LiF(100) surface bom-barded by H+ ions at grazing incidence angles as a function of beam energy, incidence and observation angles, sample crystallographic orientation, temperature and topography. The experimental results show: i) steady spectra in presence of a macroscopic surface charge, ii) shifts of the CE peak posi-tion with temperature, iii) changes in the CE peak position with the sample flattening proc-ess, iv) an increase of the CE yield for decreas-ing sample temperatures, v) a dependence of the CE emission with the crystallographic di-rection, and vi) a vanishing CE peak intensity for H+ energies lower than 20 keV. References [1] C. B. Crooks and M. E. Rudd; Phys. Rev. Lett. 25 (1970) 1599. [2] K. G. Harrison and M. W. Lucas; Phys. Lett. 33A (1970) 142. [3] G. R. Gómez, E. A. Sánchez, O. Grizzi, M.L. Martiarena and V.H. Ponce; Nucl. In-strum. and Meth. B 122 (1997) 171. [4] C. Reinhold and J. Burgdörfer, K. Kimura and M. Mannami; Phy. Rev. Lett. 73 (1994) 2508 [5] T. Iitaka, Y.H. Ohtuki, A. Koyama and H. Ishikawa; Phys. Rev. Lett. 65 (1990) 3160. [6] M.S. Gravielle, J.E. Miraglia, G.G. Otero E.A. Sánchez and O. Grizzi, Phys. Rev. A 69, 042902 (2004). [7] M.L. Martiarena, Nucl. Instrum. and Meth. B, (2005), accepted for publication. [8] M.L. Martiarena and V.H. Ponce, J. of Phys. B: At. Mol. Opt. Phys. 36, 2991-3007 (2003). [9] G.R. Gómez, O. Grizzi, E.A. Sánchez and V.H. Ponce; Phys. Rev. B 58 (1998) 7403. [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). References [1] C. B. Crooks and M. E. Rudd; Phys. Rev. Lett. 25 (1970) 1599. [2] K. G. Harrison and M. W. Lucas; Phys. Lett. 33A (1970) 142. [3] G. R. Gómez, E. A. Sánchez, O. Grizzi, M.L. Martiarena and V.H. Ponce; Nucl. In-strum. and Meth. B 122 (1997) 171. [4] C. Reinhold and J. Burgdörfer, K. Kimura and M. Mannami; Phy. Rev. Lett. 73 (1994) 2508 [5] T. Iitaka, Y.H. Ohtuki, A. Koyama and H. Ishikawa; Phys. Rev. Lett. 65 (1990) 3160. [6] M.S. Gravielle, J.E. Miraglia, G.G. Otero E.A. Sánchez and O. Grizzi, Phys. Rev. A 69, 042902 (2004). [7] M.L. Martiarena, Nucl. Instrum. and Meth. B, (2005), accepted for publication. [8] M.L. Martiarena and V.H. Ponce, J. of Phys. B: At. Mol. Opt. Phys. 36, 2991-3007 (2003). [9] G.R. Gómez, O. Grizzi, E.A. Sánchez and V.H. Ponce; Phys. Rev. B 58 (1998) 7403. [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). The experimental results show: i) steady spectra in presence of a macroscopic surface charge, ii) shifts of the CE peak posi-tion with temperature, iii) changes in the CE peak position with the sample flattening proc-ess, iv) an increase of the CE yield for decreas-ing sample temperatures, v) a dependence of the CE emission with the crystallographic di-rection, and vi) a vanishing CE peak intensity for H+ energies lower than 20 keV. References [1] C. B. Crooks and M. E. Rudd; Phys. Rev. Lett. 25 (1970) 1599. [2] K. G. Harrison and M. W. Lucas; Phys. Lett. 33A (1970) 142. [3] G. R. Gómez, E. A. Sánchez, O. Grizzi, M.L. Martiarena and V.H. Ponce; Nucl. In-strum. and Meth. B 122 (1997) 171. [4] C. Reinhold and J. Burgdörfer, K. Kimura and M. Mannami; Phy. Rev. Lett. 73 (1994) 2508 [5] T. Iitaka, Y.H. Ohtuki, A. Koyama and H. Ishikawa; Phys. Rev. Lett. 65 (1990) 3160. [6] M.S. Gravielle, J.E. Miraglia, G.G. Otero E.A. Sánchez and O. Grizzi, Phys. Rev. A 69, 042902 (2004). [7] M.L. Martiarena, Nucl. Instrum. and Meth. B, (2005), accepted for publication. [8] M.L. Martiarena and V.H. Ponce, J. of Phys. B: At. Mol. Opt. Phys. 36, 2991-3007 (2003). [9] G.R. Gómez, O. Grizzi, E.A. Sánchez and V.H. Ponce; Phys. Rev. B 58 (1998) 7403. [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). References [1] C. B. Crooks and M. E. Rudd; Phys. Rev. Lett. 25 (1970) 1599. [2] K. G. Harrison and M. W. Lucas; Phys. Lett. 33A (1970) 142. [3] G. R. Gómez, E. A. Sánchez, O. Grizzi, M.L. Martiarena and V.H. Ponce; Nucl. In-strum. and Meth. B 122 (1997) 171. [4] C. Reinhold and J. Burgdörfer, K. Kimura and M. Mannami; Phy. Rev. Lett. 73 (1994) 2508 [5] T. Iitaka, Y.H. Ohtuki, A. Koyama and H. Ishikawa; Phys. Rev. Lett. 65 (1990) 3160. [6] M.S. Gravielle, J.E. Miraglia, G.G. Otero E.A. Sánchez and O. Grizzi, Phys. Rev. A 69, 042902 (2004). [7] M.L. Martiarena, Nucl. Instrum. and Meth. B, (2005), accepted for publication. [8] M.L. Martiarena and V.H. Ponce, J. of Phys. B: At. Mol. Opt. Phys. 36, 2991-3007 (2003). [9] G.R. Gómez, O. Grizzi, E.A. Sánchez and V.H. Ponce; Phys. Rev. B 58 (1998) 7403. [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). + ions at grazing incidence angles as a function of beam energy, incidence and observation angles, sample crystallographic orientation, temperature and topography. The experimental results show: i) steady spectra in presence of a macroscopic surface charge, ii) shifts of the CE peak posi-tion with temperature, iii) changes in the CE peak position with the sample flattening proc-ess, iv) an increase of the CE yield for decreas-ing sample temperatures, v) a dependence of the CE emission with the crystallographic di-rection, and vi) a vanishing CE peak intensity for H+ energies lower than 20 keV. References [1] C. B. Crooks and M. E. Rudd; Phys. Rev. Lett. 25 (1970) 1599. [2] K. G. Harrison and M. W. Lucas; Phys. Lett. 33A (1970) 142. [3] G. R. Gómez, E. A. Sánchez, O. Grizzi, M.L. Martiarena and V.H. Ponce; Nucl. In-strum. and Meth. B 122 (1997) 171. [4] C. Reinhold and J. Burgdörfer, K. Kimura and M. Mannami; Phy. Rev. Lett. 73 (1994) 2508 [5] T. Iitaka, Y.H. Ohtuki, A. Koyama and H. Ishikawa; Phys. Rev. Lett. 65 (1990) 3160. [6] M.S. Gravielle, J.E. Miraglia, G.G. Otero E.A. Sánchez and O. Grizzi, Phys. Rev. A 69, 042902 (2004). [7] M.L. Martiarena, Nucl. Instrum. and Meth. B, (2005), accepted for publication. [8] M.L. Martiarena and V.H. Ponce, J. of Phys. B: At. Mol. Opt. Phys. 36, 2991-3007 (2003). [9] G.R. Gómez, O. Grizzi, E.A. Sánchez and V.H. Ponce; Phys. Rev. B 58 (1998) 7403. [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). References [1] C. B. Crooks and M. E. Rudd; Phys. Rev. Lett. 25 (1970) 1599. [2] K. G. Harrison and M. W. Lucas; Phys. Lett. 33A (1970) 142. [3] G. R. Gómez, E. A. Sánchez, O. Grizzi, M.L. Martiarena and V.H. Ponce; Nucl. In-strum. and Meth. B 122 (1997) 171. [4] C. Reinhold and J. Burgdörfer, K. Kimura and M. Mannami; Phy. Rev. Lett. 73 (1994) 2508 [5] T. Iitaka, Y.H. Ohtuki, A. Koyama and H. Ishikawa; Phys. Rev. Lett. 65 (1990) 3160. [6] M.S. Gravielle, J.E. Miraglia, G.G. Otero E.A. Sánchez and O. Grizzi, Phys. Rev. A 69, 042902 (2004). [7] M.L. Martiarena, Nucl. Instrum. and Meth. B, (2005), accepted for publication. [8] M.L. Martiarena and V.H. Ponce, J. of Phys. B: At. Mol. Opt. Phys. 36, 2991-3007 (2003). [9] G.R. Gómez, O. Grizzi, E.A. Sánchez and V.H. Ponce; Phys. Rev. B 58 (1998) 7403. [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). + energies lower than 20 keV. References [1] C. B. Crooks and M. E. Rudd; Phys. Rev. Lett. 25 (1970) 1599. [2] K. G. Harrison and M. W. Lucas; Phys. Lett. 33A (1970) 142. [3] G. R. Gómez, E. A. Sánchez, O. Grizzi, M.L. Martiarena and V.H. Ponce; Nucl. In-strum. and Meth. B 122 (1997) 171. [4] C. Reinhold and J. Burgdörfer, K. Kimura and M. Mannami; Phy. Rev. Lett. 73 (1994) 2508 [5] T. Iitaka, Y.H. Ohtuki, A. Koyama and H. Ishikawa; Phys. Rev. Lett. 65 (1990) 3160. [6] M.S. Gravielle, J.E. Miraglia, G.G. Otero E.A. Sánchez and O. Grizzi, Phys. Rev. A 69, 042902 (2004). [7] M.L. Martiarena, Nucl. Instrum. and Meth. B, (2005), accepted for publication. [8] M.L. Martiarena and V.H. Ponce, J. of Phys. B: At. Mol. Opt. Phys. 36, 2991-3007 (2003). [9] G.R. Gómez, O. Grizzi, E.A. Sánchez and V.H. Ponce; Phys. Rev. B 58 (1998) 7403. [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003). 58 (1998) 7403. [10] E.A. Sánchez, G. Otero, N. Tognalli, O. Grizzi and V.H. Ponce, Nucl. Instr. and Meth. B 203, 41-48 (2003).