Electron-impact excitation ofXΣg+1(v″=0)to the

M. A. Khakoo

¹

,

C. P. Malone

²

,

P. V. Johnson

³

et al.

Abstract

states in N 2 from the X 1 ⌺ g + ͑vЉ =0͒ ground level are presented. The DCSs were obtained from energy-loss spectra in the region of 12 to 13.82 eV measured at incident energies of 17.5, 20, 30, 50, and 100 eV and for scattering angles ranging from 2°to 130°. The analysis of the spectra follows a different algorithm from that employed in a previous study of N 2 for the valence states ͓Khakoo et al. Phys. Rev. A 71, 062703 ͑2005͔͒, since the 1 ⌸ u and 1 ⌺ u + states form strongly interactingRydberg-valence series. The results are compared with existing data.Energy-loss spectra were then accumulated in the energyloss range of 12-14.5 eV and unfolded in the energy-loss range of 12-13.82 eV, leaving all vibrational levels within

THE HIGH-RESOLUTION EXTREME-ULTRAVIOLET SPECTRUM OF N 2 BY ELECTRON IMPACT

“…These observations are supported by the ratio of 100 eV and 20 eV excitation functions deduced by Ajello et al (1989) and Malone et al (2012). The former found a ratio of 3.3 in the fluorescence signal of b (16), and the latter deduced a value of 1.3 averaged over b (v = 0-10) by analyzing the electron energy-loss measurements of Khakoo et al (2008). The difference between these two measurements is in agreement with the vibrational dependence observed here.…”

High-resolution Fourier-transform extreme ultraviolet photoabsorption spectroscopy of 14N15N

“…[1][2][3][4] On the experimental side, a variety of techniques have been employed to chart the dipole-allowed absorption spectrum of N 2 which begins at 100 nm and extends to shorter wavelengths, thus restricting optical experiments to windowless techniques. Electron-energy-loss spectroscopy has revealed many prominent features at low resolution [5][6][7] which have been recorded with greater precision by means of classical spectroscopy in emission [8][9][10] and in absorption. [11][12][13] The finest resolution has been achieved by using combinations of molecular beams and narrow-band tunable extreme ultraviolet (XUV) laser sources.…”

“…These 3 u levels are not accessible by optical transitions from the X 1 + g ground state, so have been observed only sparsely and often by indirect means. 7,45,46 An experimentally refined set of electronic-transition moments was incorporated into the CSE model 47 and allowed for the quantitative reproduction of experimental absolute f-values for many 14 N 2 transitions to 1 u excited-levels. Fourier-transform spectroscopy (FTS) is a powerful tool which is widely used for studies at infrared and visible wavelengths, and has been extended to the vacuum-ultraviolet (VUV) by one previous instrument.…”

Benchmarking electronic-state excitation cross sections for electron-N2collisions

“…It is therefore not surprising that significant effort, particularly at the Jet Propulsion Laboratory (JPL) and also more recently at the Fullerton campus of the University of California [7][8][9][10][11][12][13][14][15], has gone into measuring differential cross sections (DCSs) and integral cross sections for the electron impact excitation of the electronic states in N 2 . A summary of the early results can be found in Ref.…”

“…A summary of the early results can be found in Ref. [16], while those from the more recent measurements are detailed in the JPL/Fullerton papers [11][12][13][14][15]. Unfortunately, despite all these endeavors, if we were to characterize the level of agreement between these studies, over the common energy, angular range, or both, for the 17 lower-lying N 2 electronic states, then we could only conclude that it remains "patchy" at best.…”