Rotational and vibrational excitation of sputtered diatomic molecules

The rotational and vibrational level population distributions of ground and electronically excited states of several homonuclear and heteronuclear molecules are calculated for direct ejection, association, and associative ionization mechanisms of molecule sputtering. The cascade properties, formation mechanism, initial atom separation, and axis orientation to the surface are clearly reflected in the sputtered molecule distributions. In general, extensive non-Boltzmann rotational and vibrational distributions are predicted. The probability that an atom pair survives the ejection, for typical sputtering parameters, is high; approximately 50% for homonuclear molecules to near 100% for hydrides. The predictions are compared with experimental optical emission spectra in the accompanying paper.