Atomic, molecular, and continuum radiation from ion-bombarded B and B₂O₃

Abstract

Inert-gas ion impact on elemental boron and B2O3 in the presence of hydrogen or oxygen containing gases results in a rich variety of atomic, molecular, and "continuum" optical emission. In the presence of gaseous O2, some 20 different features due to OII are observed with elemental B. These are the first oxygen photon signals in the visible reported in a sputtering experiment. Independent of the gas present, B2O3 yields unresolved radiation ("continuum"), the latter coinciding with the general region of the A2Π → X2Σ+ system of BO. Bombardment of elemental B in the presence of gaseous H2 or CH4 leads to emission from the A1Π → X1Σ+ system of BH. The BH molecule can be characterized in terms of an effective rotational "temperature" (2700-3800 K), a kinetic-energy threshold (12-20 eV), and a saturation-type dependence of the signal on the beam current. Radiation from the BH molecule was observed to be surprisingly intense. We note that the emitting A1Π state correlates adiabatically with groundstate B and H atoms. It is hypothesized that this may play a major role in the mechanism of ion-bombardment-induced creation of molecular excited species. © 1981.