Vibrationally resolved photoemissions of N2 (C3Πu → B3Πg) and CO (b3Σ+ → a3Π) by low-energy electron impacts

Vibrationally resolved photoemission spectra of the electronic-state transitions C3Πu → B3Πg of N2 and b3Σ+ → a3Π of CO following low-energy electron impacts are measured with a crossed-beam experimental arrangement. The absolute cross sections of C3Πu (ν′) → B3Πg (ν″) of N2 are presented for the vi...

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Veröffentlicht in:The Journal of chemical physics 2020-07, Vol.153 (2), p.024301-024301
Hauptverfasser: Meng, Xin, Wu, Bin, Gao, Xiao-Fei, Xie, Jing-Chen, Li, Hao, Yu, Yuanqin, Zhao, Dong-Feng, Tian, Shan Xi
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Sprache:eng
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Zusammenfassung:Vibrationally resolved photoemission spectra of the electronic-state transitions C3Πu → B3Πg of N2 and b3Σ+ → a3Π of CO following low-energy electron impacts are measured with a crossed-beam experimental arrangement. The absolute cross sections of C3Πu (ν′) → B3Πg (ν″) of N2 are presented for the vibrational state-to-state transitions (ν′,ν″) = (0,0), (0,1), (1,0), (1,2), and (2,1). The excitation cross sections of the metastable state C3Πu of N2 show the maxima at the electron-impact energies 14.10 (ν′ = 0) eV and 14.50 (ν′ = 1) eV, which are potentially related to the core-excited vibrational Feshbach resonant state 2Σu+ of N2− formed by electron attachment. The absolute cross sections of b3Σ+ (ν′ = 0) → a3Π (ν″ = 0, 1, 2, 3, 4) of CO are given by the calibrations with those of N2 measured in this work. Besides the maximum excitation cross section 5.85 × 10−18 cm2 at 10.74 eV of the CO b3Σ+ (ν′ = 0) state, some fine structures on the excitation function profile are attributed to different shapes and Feshbach resonant states of CO− formed by electron attachment, while the others arise from the direct electron-impact excitation. Some discrepancies, particularly for N2, between the present data and the results available in the literature studies arise from different experimental techniques and data-processing procedures. Furthermore, contributions of physical processes such as wave-packet evolution and non-Franck–Condon dynamics are highlighted here.
ISSN:0021-9606
1089-7690
DOI:10.1063/5.0011431