Collisional population channels of the [formula omitted] state and their impact on the fluorescence analysis of extensive air showers

Abstract

Experimental evidence is found for the presence of collisional excitation mechanisms populating the vibrational levels v ′ = 0 , 1 of the N 2 ( C 3 Π u ) state in addition to electron impact excitation. Relative excitation efficiencies of the levels v ′ = 0 , 1 and 2 are calculated for low energy ( ∼ 10 keV ) electron beam excitation. A summary of our measured values for the quenching rate constants for v ′ = 0 and 1 by ground state molecular nitrogen and water vapour is given. The impact of vibrational relaxation within the N 2 ( C Π u 3 ) state on fluorescence emission is discussed.