A study of electron impact excitation of NO: The vacuum ultraviolet from 40 to 170 nm

Abstract

The electron impact induced fluorescence spectrum of NO at 200 eV has been measured in a crossed‐beam experiment. The wavelength range studied spanned the range of the vacuum ultraviolet (VUV) from 40 to 170 nm. The basis of the absolute cross sections was the newly established Ly α cross section standard from electron impact dissociation of H2. By comparison with this standard the cross section of the N I (120.0 nm) transition produced by dissociative excitation of 200 eV was established to be 1.73 ± 0.38 × 10−18 cm². The cross section of all other features in the VUV were measured. The extreme ultraviolet spectrum from 40 to 120 nm consists entirely of emissions from excited N I, N II, O I, and O II atomic dissociation fragments. In addition, in the far ultraviolet (FUV) from 120 to 170 nm we report a measurement of the cross section of the NO+(A¹Π → X¹Σ+) Baer‐Miescher (BM) bands. We develop a band model of the FUV spectrum which consists of the BM bands, including the known variation of the electronic transition moment and the β′ bands (B′²Δi → X²Πr). Identification of the (4, 0) β′ band has allowed an estimate of the electronic emission cross section of the B′²Δi → X²Πr transition.

Dissociative excitation of N2O by electron impact

“…where e − (E i ) is an ionized electron. The NO ionization energy is 9.26 eV [26,27], so with a threshold of ∼15 eV, we would expect the opening of the ionization channel to occur at approximately 24 eV. Supporting this assignment is the fact that NO + is the dominant fragment ion produced by electron impact [24,28].…”

“…The feature observed at 105.4 nm could not be attributed to any emission lines listed in the NIST database corresponding to either N I, N II, O I or O II. Thus, the designated transitions for the 105.4 nm feature were taken from Ajello et al [27] and electronic configurations are not explicitly listed. b The degree to which each listed transition contributes to the observed features is ranked according to the relative intensities listed in the NIST Atomic Spectra Database [16]: (1) dominant, (2) potentially significant,…”

Photoemission Cross Sections for Atomic Transitions in the Extreme Ultraviolet due to Electron Collisions with Atoms and Molecules

“…Stone and Zipf (1972a) measure three N I cross sections between 120.0 and 149.3 nm. An extensive study of the NO emissions between 40 and 270 nm has been made by Ajello and co-workers and will be published in a forthcoming paper (Ajello et al 1989).…”

Dissociative excitation of NO2by electron impact

“…Interestingly, the electron-impact-induced VUV spectra of NO for 100 eV and 200 eV impact energies are dramatically different than the spectra for both NO 2 and N 2 O at 100 eV [30][31][32]. In particular, they exhibit pronounced molecular features, which thus far have only been observed at near threshold (∼25 eV) impact energy in N 2 O [18].…”

“…the approximate spectral resolution; FWHM). Identification of the 105.2 nm feature was taken from Ajello et al [32] and electronic configurations are not explicitly listed. b The degree to which each listed transition contributes to the observed features is ranked according to the relative intensities listed in the NIST Atomic Spectra Database [36]: 1, dominant; 2, potentially significant; 3, insignificant.…”