Experimental determination of electron effective attenuation lengths in silicon dioxide thin films using synchrotron radiation - II. Effects of elastic scattering
H. Shimada et al., Experimental determination of electron effective attenuation lengths in silicon dioxide thin films using synchrotron radiation - II. Effects of elastic scattering, SURF INT AN, 29(5), 2000, pp. 336-340
The effective attenuation lengths (EALs) of photoelectrons in thin silicon
dioxide films on an Si(100) substrate were measured as a function of electr
on energy using synchrotron radiation as an energy-tunable excitation sourc
e. The ratios of EALs to inelastic mean free paths (IMFPs) calculated from
optical data were independent of electron energy from 140 to 1000 eV when t
he analyzer axis was normal to the sample surface and the angle between the
incident x-rays and the surface normal was 55 degrees. This result indicat
es that the effects of elastic electron scattering (in causing the EAL to b
e less than the corresponding IMFP) were independent of electron energy for
this configuration, The EALs measured with normally incident x-rays and el
ectron emission at 55 degrees with respect to the surface normal were large
r than EALs for the other configuration, In particular, the difference for
the EALs at the two configurations was similar to 25% for electron energies
below 200 eV, The angular range suitable for satisfactory angle-resolved a
nalyses with x-ray photoelectron spectroscopy should therefore be limited t
o <55 degrees when the electron energies are less than similar to 500 eV, C
opyright (C) 2000 John Whey & Sons, Ltd.