Photodissociation dynamics of NH2OH from the first absorption band

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Abstract
The dynamics of the photofragmentation of hydroxylamine from its lowest excited electronic state, Ã 1A’, have been investigated. The main dissociation channel leads to H+H+HNO with a quantum efficiency of 1.7 for hydrogen atoms. The H atoms have been analyzed by laser induced fluorescence using a frequency tripled dye laser with sub‐Doppler resolution. A sequential decay process is proposed where the first ejected H fragment leaves a highly vibrationally excited intermediate which dissociates after intramolecular vibrational redistribution into H+HNO. Another photodissociation channel leads to OH(X 2Π) and NH2(Ã 2A1). NH2(Ã) has been detected by its emission spectrum, Ã 2A1→X̃ 2B1, indicating strong vibrational excitation of the ν2 bending mode. The OH product shows no vibrational excitation, whereas rotational states up to N=20 have been observed. Observation of the product state distributions and of the 〈μ⋅v〉 and 〈v⋅J〉 correlations yield a qualitative picture of the upper potential energy surface (PES). Out of the nine coordinates characterizing the normal vibrational modes of H2NOH only the NO distance, the NOH bending angle (responsible for OH rotation), and the NH2 bending angle (responsible for NH2 bending motion) are involved in the NH2+OH fragmentation channel.