Experimental determination of the Einstein coefficients for the N2(B–A) transition

Abstract

We have used a branching-ratio technique to measure the relative variation in the transition-dipole moment with internuclear separation for the N2(B–A) transition. Our spectral observations cover the range from 500 to 1800 nm, and use several different detectors and excitation sources. The data from different sets are consistent in the regions of spectral overlap. Using well established values for the radiative lifetimes of N2(B,v′≥5) allows the relative dipole-moment function to be placed on an absolute basis. From the dipole-moment function and a set of RKR-based Franck–Condon factors which we have computed, we derive Einstein coefficients covering the range v′=0–12 and v″=0–20. Our results indicate that currently accepted lifetimes for N2(B,v′=0–2) should be revised upwards by 20% to 40%.