Results 1 - 1 of 1
Results 1 - 1 of 1. Search took: 0.015 seconds
[en] Electron-impact excitation of H2 triplet states plays an important role in the heating of outer planet upper thermospheres. The state is the third ungerade triplet state, and the – emission is the largest cascade channel for the state. Accurate energies of the (v, J) levels are calculated from an ab initio potential energy curve. Radiative lifetimes of the (v, J) levels are obtained by an accurate evaluation of the – transition probabilities. The emission yields are determined from experimental lifetimes and calculated radiative lifetimes and are further verified by comparing experimental and synthetic – spectra at 20 eV impact energy. Spectral analysis revealed that multipolar components beyond the dipolar term are required to model the – excitation, and significant cascade excitation occurs at the (v = 0,1) levels. Kinetic energy (Ek) distributions of H atoms produced via predissociation of the state and the −− cascade dissociative emission are obtained. Predissociation of the state produces H atoms with an average Ek of 2.3 ± 0.4 eV/atom, while the Ek distribution of the −− channel is similar to that of the –− channel and produces H(1s) atoms with an average Ek of 1.15 ± 0.05 eV/atom. On average, each H2 excited to the state in an H2-dominated atmosphere deposits 3.3 ± 0.4 eV into the atmosphere, while each H2 directly excited to the state gives 2.2–2.3 eV to the atmosphere. The spectral distribution of the calculated – continuum emission due to the – excitation is significantly different from that of direct excitation.