Photodissociation dynamics of à state ammonia molecules. I. State dependent μ‐v correlations in the NH2(ND2) products

摘要: The H(D) Rydberg atom photofragment translational spectroscopy technique has been applied to a further detailed investigation of the photodissociation dynamics NH3 and ND3 molecules following excitation lowest two (v2=0 1) vibrational levels first excited (A 1A2″) singlet electronic state. Analysis respective total kinetic energy release spectra, recorded at number scattering angles Θ [where is angle between e vector photolysis photon time‐of‐flight (TOF) axis], enables quantification striking, quantum state dependent, μ‐v correlation in NH2(ND2) products. spatial distribution flux photofragments rather isotropic (βlab∼0). However, more careful analysis way which TOF spectra vary with reveals that each H+NH2(D+ND2) product channel different ‘‘partial’’ anisotropy parameter, βlab(v2,N), associated it: ejected by those dissociate yield fragments little rotational largely appear plane molecule (i.e., perpendicular transition moment C3 axis parent, β tending towards −1). Conversely, atoms formed association most highly rotationally partner tend recoil almost parallel this β→+2). Such behavior rationalized context known potential surfaces A X states ammonia using classical, angular momentum conserving impact parameter model we assume all established ‘‘point’’ conical intersection H–NH2(D–ND2) dissociation coordinate. We conclude reemphasizing level care needed interpreting experimentally measured parameters situations where there averaging over either initial (parent) or final (product) states.