Integral Cross Sections for Electron Impact Excitation of Rydberg and Valence States of Molecular Nitrogen
Abstract
We present integral cross sections (ICSs) for electron impact excitation of N2 out of the ground state X (v=0), to the b, c3, o3, b', c'4, G, and F electronic states at incident energies ranging between 17.5 eV and 100 eV. The ICSs were derived from the differential cross sections (DCSs) of Khakoo et al. [Phys. Rev. A 77, 012704 (2008)], which were obtained by unfolding energy loss spectra in the ∼12-13.82 eV range. Recently, Heays et al. [Phys. Rev. A 85, 012705 (2012)] measured comparable higher resolution energy loss spectra, with a significantly different apparatus configuration, but in agreement with the Khakoo et al. (2008) spectra. This latter additional effort provided further confidence in the accuracy of the DCSs upon which the present ICS results are based. Of the higher-lying states studied, five are singlet states that radiate to the ground state via dipole allowed transitions. These include the b and b' valence states and the c'4 Rydberg state that give rise to the Birge-Hopfield I, II, and Carroll-Yoshino bands, respectively, all of which are observed in the atmospheres of Earth, Titan, and Triton. The c3 and o3 Rydberg states give rise to the Worley-Jenkins and Worley series of Rydberg bands, respectively. However, these emissions are not readily observed since predissociation for the c3 and o3 states approaches 100%. As such, direct electron excitation measurements, such as those presented here are superior to standard (spontaneous) emission based measurements in this case.
- Publication:
-
APS Division of Atomic, Molecular and Optical Physics Meeting Abstracts
- Pub Date:
- June 2012
- Bibcode:
- 2012APS..DMP.Q1051M