Total cross-section for low-energy and very low-energy electron collisions with O₂

Abstract

An absolute total cross-section for electron scattering from O2 is obtained in the energy range from 20 eV down to 16 meV with a very narrow electron energy width of 7 meV, using the threshold-photoelectron source employing synchrotron radiation. The total cross-section obtained in the present study generally agrees well with those obtained in previous experimental works in the energy region where the previous experimental total cross-sections agree with each other. At lower energies, several features are found, including the very large contribution of the resonance to the total cross-section. The resonance energies and the resonance widths of the individual vibrational states of the resonance are determined from the analysis of the measured absolute total cross-section. The resonance width of the resonance of O2 is found to be much narrower than the value estimated from previous high-resolution experiments and theoretical calculations.

Recent total cross section measurements in electron scattering from molecules

“…to the O − 2 ( 2 Π g ) resonant states, very low-energy results of Okumura et al [71] are consistent with those of Buckman et al [78], collected earlier using time-of-flight technique of 2-10 meV energy resolution.…”

“…Molecular targets, and references in the text Baylor University, C2H4 (ethylene), C3H6 (propene), C4H8 (butene), C4H6 (1,3-butadiene) [144]; Waco, USA C2H2 (acetylene), C3H4 (propyne) [145] Gdańsk University HCOOH (formic acid) [86]; C4H4O (furan) [87]; C3H3NO (isoxazole) [90]; of Technology, C5H5N (pyridine) [107]; C5H10O (tetrahydropyran) [111]; Gdańsk, Poland (CH3)2CO (acetaldehyde) [116]; (CF3)2CO (hexafluoroacetone) [117]; X(CH3)4 (X=C,Si,Ge) [126]; SnCl4 [127]; C4H8 (1-butene, 2-methylpropene) [136]; C5H10 (1-pentene) [138]; C5H10 (2-methyl-2-butene), C6H12 (2,3-dimethyl-2-butene) [137]; C2H2 (acetylene), C4H6 (1-butyne) [139]; C4H6 (1,2-butadiene) [141]; C5H6 (2-methyl-1-buten-3-yne) [142]; C5H8 (2-methyl-1,3-butadiene) [143] Institute of Technology, N2 (nitrogen) [62]; O2 (oxygen) [71] Tokyo, Japan Instituto de Matemáticas N2 (nitrogen) [63]; CH2Cl2 (dichloromethane) [124] y Fisica Fundamental, C4H4S (thiophene) [88]; C5H4O2 (furfural) [89]; C4H8O (tetrahydrofuran) [94]; (CSIC), Madrid, Spain C6H6 (benzene) [98]; C6H5OH (phenol) [103]; C5H5N (pyridine) [105,106]; C4H4N2 (pyrimidine) [109]; C4H4N2 (pyrazine) [110]; C6H4O2 (para-benzoquinone) [112]; C4H3F7O (sevoflurane) […”

“…Molecular nitrogen and oxygen, two main constituents of the Earth atmosphere, are amongst the targets which were very intensively investigated in the electronscattering experiments. The most up-to-date measurements of electron-scattering absolute TCSs for the N 2 molecule have been carried out by Kitajima et al [62] and Lozano et al [63], while those for O 2 were reported very recently by Okumura et al [71]. Experiments of Kitajima et al and Okumura et al have been performed • [69]; ▽ [70].…”

“…At very low electron-impact energies, the recent TCS findings of Kitajima et al are consistently lower than those reported earlier by Hoffmann et al [70], measured also with very high energy resolution. Figure 4 presents the absolute TCSs for electron scattering from O 2 molecules in the energy range from 16 meV to 20 eV measured by Okumura et al [71], with an electron energy width of 7 meV.…”