Proposed standard inelastic differential electron scattering cross sections; Excitation of the 21 P level in He

Abstract

Differential and integral cross section data for electron-impact excitation of the 21p level in He have been critically reviewed. Experimental and theoretical results have been compared and a set of differential cross sections at 20 ° scattering angle in the 25 to 500 eV impact energy range has been deduced based on all available information. It is proposed that this set of data represents the most accurate inelastic differential cross sections available at the present time and could be used as a secondary standard for normalization of cross sections.

Cross sections for electron impact excitation of the vibrationally resolved AΠ1 electronic state of carbon monoxide

“…Unfortunately, there are few cases where the accuracy of such inelastic cross sections is sufficient so that they can be considered a "standard." One possible example is the excitation of the 2 1 P level in He, where a substantial body of experimental 21 and theoretical 22 work exists. 23 As a test case we measured the energy dependence ͑at each T of interest͒ of 2 1 P to the elastic intensity ratio in He at 20°, and compared it with the accepted [21][22][23] values.…”

“…One possible example is the excitation of the 2 1 P level in He, where a substantial body of experimental 21 and theoretical 22 work exists. 23 As a test case we measured the energy dependence ͑at each T of interest͒ of 2 1 P to the elastic intensity ratio in He at 20°, and compared it with the accepted [21][22][23] values. After consideration of other energy-dependent experimental parameters ͑such as the incident electron beam current͒, the difference between the measured and standard ratios was considered to be a reasonable indicator of the apparatus transmission function.…”

Cross sections and oscillator strengths for electron-impact excitation of the ÃB11 electronic state of water

“…The "standard" 2 1 P differential cross sections were then employed to fix the corresponding absolute scale of the H 2 O electronic states. 52 Great care was also taken at Sophia University to establish the transmission of the analyzers over the relevant energy-loss range, with full details of this procedure being found in Kitajima et al 51 At 20-50 eV there is a potential 3 B 1 contribution to the 1 B 1 signal ͑see Fig. 1͒, so that these data were sent to Flinders for deconvolution.…”

A -band methyl halide dissociation via electronic curve crossing as studied by electron energy loss spectroscopy

“…The energy dependence of 2 1 P to the elastic intensity ratio in helium at 20°w as measured, and compared with well-known values. [18][19][20] After consideration of other experimental parameters, the difference between the measured and standard ratios was considered to be a reasonable indicator of the apparatus transmission function. This transmission function was then used when needed to correct the measured EELS spectra.…”

“…For angles smaller than 10°, where the elastic signal to noise becomes problematic, a second normalization technique was used to measure the intensity ratio for electronic excitation of the targets relative to the excitation of the 2 1 P state in helium. The 2 1 P state DCS, 18 could then be employed to fix the corresponding absolute scales of the electronic excitations in the EELS.…”