Analytical expression for K- and L-shell cross sections of neutral atoms near ionization threshold by electron impact

C.S. CAMPOS; M.A.Z. VASCONCELLOS; J.C. TRINCAVELLI; S. SEGUI

JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS

IOP

Año: 2007 vol. 40 p. 3835 - 3841

0953-4075

An analytical expression is proposed to describe the K- and L-shell ionizationcross sections of neutral atoms by electron impact over a wide range of atomicnumbers (4 Z 79) and over voltages U < 10. This study is based on theanalysis of a calculated ionization cross section database using the distorted-wave first-order Born approximation (DWBA). The expression proposed forcross sections relative to their maximum height involves only two parametersfor each atomic shell, with no dependence on the atomic number. On the otherhand, it is verified that these parameters exhibit a monotonic behaviour withthe atomic number for the absolute ionization cross sections, which allows usto obtain analytical expressions for the latter.