Emission of the Werner Band System and Lyman-α Radiation for 0.05–6-keV Electrons in H2

Abstract

Articles you may be interested inCurrent response characteristics of microchannel plates xray detector using synchrotron radiation (0.6-2 keV and 5-20 keV) Rev. Sci. Instrum. 59, 252 (1988); 10.1063/1.1140236 Effect of rotational coupling on emission probabilities of Lyman and Werner band systems of the vacuum ultraviolet spectrum of H2We have measured relative cross sections as a function of impact energy for the emission of Werner bands C(2Ptr lII~)-(Isoll:g +) and Lyman-a radiation for 0.05-6-keV electrons on molecular hydrogen. The cross sections for the Werner bands are normalized on theoretical Born or Bethe cross sections, evaluated by means of the theoretical generalized oscillator strengths of Miller and Krauss and the theoretical optical oscillator strengths and transition probabilities of Allison and Dalgarno. By comparing the cross sections thus obtained and the relative intensity measurements, the sensitivity of our optical detection system can be determined between about 1030 and 1250 A. It is then also possible to bring the relative cross sections for Lyman-a radiation at 1215.7 A on an absolute scale. The latter cross sections appear to be 1.31 times smaller than those reported by Vroom and De Heer, which data were normalized on the so-called countable ultraviolet cross sections of Fite and Brackmann. In the latter normalization, the contribution of the Werner bands to the countable ultraviolet cross sections has been neglected.Nonempirical LCAO MO SCF calculations using Gaussian-type functions have been used to predict the geometries of acetylene, vinylidene carbene, 1I"-protonated acetylene, and the vinyl cation. The computed geometry and molecular ionization potential of acetylene give good agreement with experimental data. The vinyl cation is predicted to be more stable than 1I"-protonated acetylene by about 18 kcal/mole.

Electron impact excitation of H2: resonance excitation of B1 u (Jj 2,vj 0) and effective excitation function of EF1 g

“…While many experimental investigations of excitation cross sections of the singletungerade states have been reported (De Heer and Carrière 1971, Ajello et al 1984, Shemansky et al 1985a, Khakoo and Trajmar 1986,Liu et al 1998, the measurement of excitation functions for the singlet-gerade states such as EF 1 + g has been sparse and insufficient. Watson and Anderson (1977), Anderson et al (1977) and Day et al (1979) have reported relative excitation functions for a limited number of rovibrational levels of the EF 1 + g , GK 1 + g , and H H 1 + g states.…”

Electron Excitation, Dissociation and Ionization of H2, D2, T2, Simple Hydrocarbons and Their Ions

“…The low M& = 0.019 value of Gerhart [ l ] cannot be brought in agreement with any of the experimental electron impact data determined at an absolute scale. Different from Gerhart's [ I ] analysis, we refer to the work of Fite and Brackmann [38] and de Heer and Carriere [12]. It appears however that the values of Gerhart adopted for the sum of u2P and uZs, or M& and M&, are in reasonable agreement with the experiment.…”

“…Most work has been done on the Werner band system. Relative cross-sections for the emission of particular C(v') --f X(v") Werner lines induced by electron impact have been measured by de Heer and Carriere [12] and by Stone and Zipf [13]. More recent work has appeared from Malcolm et al [14], who also considered the polarization of radiation.…”