Quenching of NH(b 1Σ+) by O and N atoms; isotope effect in the quenching of NH and ND(b 1Σ+) by He, Ar, and N2

Abstract
Electronically excited NH and ND(b 1Σ+, v′=0) have been produced in the vacuum ultraviolet photolysis of NH3 or ND3 at pressures in the millitorr range. Absolute quenching rate coefficients have been determined for NH(b 1Σ+) with oxygen and nitrogen atoms as 1.78±0.09×10−11 and 3.38±0.07×10−11 cm3 molecule−1 sec−1, respectively, at 293°K. Quenching by He, Ar, and N2 is much slower, and for each of these quenchers the rate coefficient for quenching ND(b 1Σ+) is at least a factor of 10 lower than that for quenching NH(b 1Σ+).