Measurement of the 13 to 100 eV electron impact excitation cross section for the X 1Σ+g→a 1Πg transition in N2

Abstract

The electron impact excitation cross section for the X 1Σ+g→ a 1Πg transition in N2 has been measured from 13 to 100 eV by an inelastic electron scattering technique. The cross section varies from a maximum value of 3.6×10−17 cm2 between 15 and 18 eV to 5.2×10−18 cm2 at 100 eV. The incident electron impact energy was calibrated by an optical technique. The agreement between the measured intensities of the v′=0–6 vibrational bands of the transition and the intensities predicted by the Franck–Condon factors was found to be within experimental error. The cross section results of the present experiment are in excellent agreement with those of previous investigators obtained with a variety of techniques up to 30 eV. At the higher energies, the present values agree within experimental error with the results of Holland at 100 eV and those of Aarts between 60 and 100 eV.

A reexamination of important N2 cross sections by electron impact with application to the dayglow: The Lyman‐Birge‐Hopfield Band System and N I (119.99 nm)

“…One of us has previously published a laboratory FUV study of N2 [Ajello, 1970] in which experimental problems at electron impact energies above 30 eV seriously compromised the accuracy of the cross-section measurements of the LBH transition and atomic nitrogen multiplets. This problem has already been pointed out in the literature [Finn and Doering, 1976]. A problem of backscattering of secondary electrons from the Faraday cup led to an overestimate of cross sections for energies above 30 eV.…”

“…There still remains a need to reexamine the LBH band system and atomic multiplets by optical means with a calibrated electron impact emission spectrometer particularly in the threshold region, 8 to 20 eV. All previous 10w-ehergy laboratory studies have been carried out by electron energy loss experiments [Cartwright et al, 1977a, b;Finn and Doering, 1976] or by time of flight measurements [Borst, 1972]. A theoretical determination of the LBH excitation cross section has been performed by Chung and Lin [1972].…”

“…We consider the variation in the threshold energy behavior of each vibrational cross section. In all previously published electron impact experiments of the a•IIg state, both the electron energy loss experiments [Cartwright et al, 1977a, b;Finn and Doering, 1976] In this experiment we measure the emission cross section (cascade plus direct excitation) and predissociation cross section for the LBH band system. These results are compared to electron energy loss measurements of the direct excitation cross section.…”

Electron impact excitation cross sections for carbon monoxide

“…On the experimental side, NZ is the only molecule for which the electronic excitation cross sections have been extensively studied at low and intermediate energies (CartWright et a1 1977a, b, Chutjian et a1 1977, 1983, Finn and Doering 1976. In view of the significant experimental effort and difficulties involved in the measurement of these cross sections for molecules, it is clearly of interest to develop theoretical methods with some degree of reliability which can be applied routinely at least for linear molecules.…”

“…However, to date, there has been limited progress in the experimental determination of these cross sections (Cartwright et a1 1977a, b, Chutjian et a1 1977, 1983, Trajmar et a1 1968, 1971, Finn and Doering 1976, Linder and Schmidt 1971 as well as in the development of new theoretical methods (Chung and Lin 1978, Holley et a1 1981, Rescigno et a1 1975, Hazi 1981) for studying these cross sections. Until quite recently, Born-type approximations (Arrighini et a1 1980, Chung and Lin 1972, 1974, Chung et a1 1975, Cartwright 1970, Khare 1966, 1967 were the only practical method for calculating these inelastic cross sections.…”