Assignment of high-lying bending mode levels in the threshold photoelectron spectrum of NH2: a comparison between pyrolysis and fluorine-atom abstraction radical sources

Abstract

In this manuscript we present threshold photoelectron spectra (TPES) of the amidogen radical, NH₂, recorded at two vacuum ultraviolet synchrotron radiation beamlines, the DESIRS beamline of Synchrotron SOLEIL and the VUV beamline of the Swiss Light Source (SLS). Amidogen radicals were generated by two different methods, (a) H-atom abstraction of ammonia in a fluorine microwave discharge flow tube and (b) flash pyrolysis of methylhydrazine and diphenylmethylamine. Due to the large geometry change upon photoionization from the bent neutral molecule NH₂ ( ²B₁) to the quasi-linear cation NH₂⁺ ( ³B₁), significant activity in the bending vibration υ₂⁺ of NH₂⁺ ( ³B₁) is observed in the TPES. Transitions into a large number of υ₂⁺, K_a⁺ levels of the cation are resolved.