Photodissociation dynamics of the NH molecule under intense VUV pulses

Abstract

Photodissociation dynamics of the NH molecule excited from the triplet ground X^{3}Σ^{−} to 2^{3}Π state by resonant intense VUV pulses have been comprehensively investigated by the recently proposed theoretical treatment involving the electron-rotation coupling. The rotational dynamics are described by the Wigner D functions, and the electronic transition operators are refined with respect to the changes of the projection of the total orbital angular momentum onto the molecular axis ΔΛ. The kinetic energy release (KER) spectra and the angular distribution of photofragments are obtained by averaging over nine degenerate initial angular states, computed separately. We have shown that the KER spectra are not very sensitive to the electron-rotation coupling for different pulse intensity and energy detuning from the resonance. The angular distribution of the photofragments, on the contrary, is strongly affected by the electron-rotation coupling at the small angles between the molecular axis and laser polarization. The influence of the electron-rotational coupling shows different trends for positive and negative detunings from the resonance at variation of the pulse intensity, which is explained by sufficient changes of the rotational wave packet dynamics caused by different phases of the initial rotational states.