The electronic spectrum of acrylonitrile

Electronic and vibrational excitation of acrylonitrile by low and intermediate energy electrons

“…The lowintensity feature located at 7.895 eV was previously associated with a ͑0-0͒ transition of →* character. 7 However, its relative intensity does not seem to fit in a vibrational progression of the B or C states. So, we suggest that the 7.895 eV peak is due to the excitation of the nϭ3 term of the 2aЉ→ns series with a quantum defect ␦ϭ0.88 ͑Table VI͒.…”

“…33,34 The energy values found for the observed features are tabulated in Table II and compared to those obtained by gaseous UV absorption spectroscopy with which they are in good agreement. 7 It should be noted that other peaks of lower intensities have been evidenced in the optical spectrum due to the higher resolution. The whole structure remains similar when the impact energy is lowered at 30 eV ͓Figs.…”

“…These authors assigned this electronic transition to a →* one and analyzed the peaks in terms of vibrational excitation as shown in Table II. 7 However, the photoelectron spectroscopy studies 28 have shown that molecular orbitals are more stable than molecular orbitals. On the other hand, the gaseous phase inner-shell-electron energy loss and the NEXAFS spectroscopies have allowed the location of the * unoccupied molecular orbitals at an energy higher than that of the *.…”

“…This electronic band was also attributed to a transition of →* character in the previous UV work. 7 We have summarized in Table V all the valence excited states evidenced in this work with their reviewed assignments. The unoccupied molecular orbital energetic ordering proposed by core excitation is compared in Table V to that proposed in this work.…”

“…A previous UV absorption study has allowed the localization of several valence excited states in the 5-9 eV excitation region which have been assigned by the authors on the basis of MO calculations as well as of a vibrational analysis. 7 The lowestenergy absorption band localized at 5.884 eV has been sug-gested to be of n→* type whereas the higher bands at 6.107, 7.187, and 7.896 eV have been associated with large vibrational patterns and assigned to ͑0-0͒ transitions of →*, →*, and →* character, respectively. No assignment of Rydberg series has been carried out due to the short excitation energy domain investigated which has been restricted by about 2 eV lower than the molecular ionic ground state.…”