Proton quantum quasi-equilibrium states in liquid crystals: Analytical – Experimental study

CLAUDIO J. BONIN; CECILIA E. GONZÁLEZ; HÉCTOR H. SEGNORILE; RICARDO C. ZAMAR

Montevideo

Congreso; XII Reunión de la SUF / 96ª Reunión Nacional de de Física de la AFA; 2011

SUF / AFA

Proton spins of liquid crystal (LC) molecules are small clusters of strongly interacting spins (dipole-dipole), magnetically isolated in the average from spins at other molecules, while mechanically coupled with an orientationally ordered molecular environment. Previous work1 showed that quasi-equilibrium states (quasi-invariants (QI)) associated with constants of motion of the residual dipolar Hamiltonian HD0, can be prepared in LC through the Jeener-Broekaert (JB) experiment2. An efficient application of the QI in many fields, from the basic physics of open quantum systems and quantum information processing, to the study of cooperative molecular dynamics, demands a complete analytical description of these QI. We study the proton spin dynamics and we report the first complete characterization of a multi-spin-order QI in a spherical tensor operator basis, in a 4-spin-1/2 model, as a first approach for a typical LC (e.g. PAAd6). Following the behavior for long preparation times, we observe that the experiments in PAAd6 cannot be explained by assuming only two QI, demanding the consideration of additional QI's of more complex tensor structure5. REFERENCES 1- O. Mensio, C. E. González, and R. C. Zamar, Phys. Rev. E 71, 011704(2005). 2- J. Jeener and P. Broekaert, Phys. Rev. 157, 232(1967). 3- H. Eisendrath, W. Stone and J. Jeener, Phys. Rev. B 17, 47(1978). 4- L. Buljubasich, G. Monti, R. H. Acosta, C. J. Bonin, C. E. González, and R. C. Zamar, J. Chem. Phys. 130, 024501(2009) . 5- C. J. Bonin, PhD Thesis (2011)  http://www.famaf.unc.edu.ar/publicaciones/documents/serie_d/DFis147.pdf (cbonin@famaf.unc.edu.ar) 6- H. H. Segnorile, PhD Thesis (2009).