Electron-impact excitation and emission cross sections of the H2 B′ 1Σu+ and D 1Πu states and rotational dependence of photodissociation cross sections of the B′ 1Σu+ and D 1Πu continua

Rotational and vibrational dependence of photodissociation cross sections and oscillator strengths to the continuum levels of the H-2 B' (1)Sigma(+)(u) and D (1)Pi(u) states have been examined. The electron-impact excitation, dissociation and emission cross sections of the B' (1)Sigma(+)(u) - X (1)Sigma(+)(g) and D (1)Pi(u) - X (1)Sigma(+)(g) 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 B' (1)Sigma(+)(u) photodissociation cross section from the J(i) = 0 level is in excellent agreement with that obtained by Glass-Maujean (1986 Phys. Rev. A 33 346-50). Photoexcitation from the X (1)Sigma(+)(g) (v(i) = 0) state to the D (1)Pi(u) 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 B' (1)Sigma(+)(u) - X (1)Sigma(+)(g) (0) transition, which, in turn, leads to the noticeable temperature dependence of electron-impact excitation and emission cross sections. B' (1)Sigma(+)(u) - X (1)Sigma(+)(g) and D (1)Pi(u) - X (1)Sigma(+)(g) electron-impact excitation, emission, and dissociation cross sections, important for modelling dayglow and auroral activity in the atmospheres of the outer planets, are presented.