SPECTROSCOPIC STUDY OF ION-INDUCED PHOTON-EMISSION UNDER D+ AND HE+ BOMBARDMENT

In order to investigate the interaction of energetic ions with a solid surface, we have performed a spectroscopic study of the ion-induced photon emission under D+ or He+ bombardment with incident energies ranging from 10 to 25 keV. The line spectra of D-a (656.10 nm) and He I (578.76 nm) emitted from the reflected particles in excited states were analyzed in terms of incident ion energy, target material and residual gas pressure. With increasing incident ion energy, both the D-a and He I spectra shifted to a shorter wavelength and broadened, while the photon intensities of both the D-a and He I emission decreased. The intensities also grew with the Z number of the target materials showing a very similar relation to that reported between the reflection coefficients and the Z number. Oxygen at the surface significantly enhanced the He I emission, whereas the D-a emission was hardly influenced. Compared with oxygen, the effects of hydrogen and nitrogen on the intensity were very small. The difference could be attributed to a resonance excitation of the electrons of reflected neutrals.