Lifetime measurements of the <i>B</i> 3Π<i>g</i> state of N2 using laser excitation

Abstract

A chopped cw dye laser has been used to excite selected levels of the B 3Πg state of N2 in a molecular beam of A 3Σu+ state metastables. Laser-induced fluorescence was observed from the vibrational levels v=5 through v=12, and a photomultiplier was used in conjunction with a microcomputer system to perform time-resolved detection of the decay light. The lifetimes have been measured to an accuracy of about 3%. They show a smooth decline from 5.87 μs for v=5 to 4.11 μs for v=12. No dependence on rotational level was observed, and no contributions to the B state decay were found from intrasystem cascading of the form B→W 3Δu→B→A 3Σu+.