Electron-impact excitation and emission cross sections of the H and states and rotational dependence of photodissociation cross sections of the and continua

Abstract

Rotational and vibrational dependence of photodissociation cross sections and oscillator strengths to the continuum levels of the H and states have been examined. The electron-impact excitation, dissociation and emission cross sections of the and band systems have been obtained for the first time over a wide energy range by using calculated continuum oscillator strengths along with previously published discrete transition probabilities and Lyman and Werner bands excitation functions. The present photodissociation cross section from the Ji = 0 level is in excellent agreement with that obtained by Glass-Maujean (1986 Phys. Rev. A 33 346–50). Photoexcitation from the state to the continuum is found to be weak. The present calculation shows significant contribution of quasi-resonance, which arises from transitions to the quasi-bound levels above the dissociation limit but stabilized by the centrifugal potential. The quasi-resonance is largely responsible for the significant rotational dependence of the continuum oscillator strength of the transition, which, in turn, leads to the noticeable temperature dependence of electron-impact excitation and emission cross sections. and electron-impact excitation, emission, and dissociation cross sections, important for modelling dayglow and auroral activity in the atmospheres of the outer planets, are presented.