Eur. Phys. J. D 46, 51-57 (2008)
https://doi.org/10.1140/epjd/e2007-00278-2

Influence of pressure on the relative population of the two lowest vibrational levels of the C ³Π_u state of nitrogen for electron beam excitation

¹ Physik Department E12, Technische Universität München, 85748 Garching, Germany
² Coherent GmbH, Zielstattstrasse 32, 81379 München, Germany

Corresponding author: ^a andrei.morozov@ph.tum.de

Received: 14 June 2007
Revised: 4 September 2007
Published online: 28 September 2007

Abstract

Continuous and pulsed 12 keV electron beams were used to excite nitrogen within a gas cell at pressures ranging from 10 to 1400 hPa. The pressure dependence of the ratio of photon fluxes for emission from vibrational levels v'=0 and 1 of the C ³Π_u state has been studied. The results confirm the presence of a collisional excitation mechanism populating v'=0, 1 in addition to electron impact excitation. Rate constants of (1.27 ±0.04)×10^-11 cm³s^-1 [ v'=0] and (2.68 ±0.08)×10^-11 cm³s^-1 [ v'=1] were measured for C ³Π_u quenching by ground state nitrogen. For electron beam conditions relative excitation efficiencies of 1:0.59:0.22 for vibrational levels 0, 1 and 2 were calculated. The recorded flux ratios are compared with the predictions given by a vibrational relaxation model.