Contamination induced changes in photon emission from Nb and Nb/V alloys

Abstract

Changes in NbI and VI line emission and continuum emission with contamination by O 2 and CO background pressures have been studied from ion bombarded Nb and Nb/V alloys. Broad band continua and discrete broad features (possibly molecular) are noted. Importantly, the NbI and VI line emission intensities are found to peak at the same oxygen exposure for a particular alloy and that the exposure for the intensity peak increases with the Nb concentration of the alloy. Intensity enhancements for the atomic lines also change with the alloy concentration and are greater for the VI 411.1 nm line from the bombarded alloys than the pure V, but less for the NbI 405.9 nm line from the bombarded alloys than the pure Nb. An explanation of these changes would include the Nb, V and O atoms all influencing the excitation process, which may involve the quasimolecular formation model. These matrix effects are reported here for proton emission for the first time, and may have an important influence on SIPS chemical analysis when oxygen is present. Unlike the atomic lines, continuum emission does not reflect the changes in the alloy concentrations. The continuum emission is shown to be particularly sensitive to surface cleanliness. Significant differences in the continuum emission are found for bombardment of Nb under O 2 and Co background pressure contamination.