Optical Radiation from Electron Sputtering of Alkali Halides
Electron-surface collisions have been observed to result in the emission of optical radiation from excited atoms and molecules desorbed from alkali halide single crystal surfaces. The detected radiation included Na and Li resonance lines, hydrogen Balmer emission, and OH molecular radiation. Much previous experimental and theoretical effort has been devoted to electron stimulated desorption (ESD) of ground state neutrals and ions , and in particular from alkali halides [2,3,4]. The few studies concerned with excited particles have dealt primarily with ejected metastable neutrals . In one case involving electron bombardment fluorescence of ice, a tentative identification has been made of OH molecular radiation . The results reported here include a) the first definitive work on optical radiation from electron bombardment induced emission of excited free substrate particles , and b) the first observations of characteristic radiation from previously adsorbed free atoms and molecules.
KeywordsDust Hydroxide Auger Reso Kelly
Unable to display preview. Download preview PDF.
- 1.See for example, D. Menzel, Surf. Sci. 47, 370 (1975); T. E. Madey and J. T. Yates, Jr., Surf. Sci. 63, 203 (1977); P. J. Feibelman and M. L. Knotek, Phys. Rev. B18, 6531 (1978); D. P. Woodruff, M. M. Traum, H. H. Farrell, N. V. Smith, P. D. Johnson, D. A. King, R. L. Benbow and Z. Hurych, Phys. Rev. B21, 5642 (1980).CrossRefGoogle Scholar
- 7.In the course of their studies of electron bombardment induced exciton luminescence from NaCl, Townsend et al. mentioned observations of sodium D lines emitted from neutral excited sodium atoms which had evolved from the surface bulk, P. D. Townsend, A. Mahjoobi, A. J. Michael and M. Saidoh, J. Phys. C: Solid St. Phys. 9, 4203 (1976).CrossRefGoogle Scholar
- 8.N. H. Tolk, L. C. Feldman, J. Kraus, R. J. Morris, M. M. Traum and J. C. Tully, submitted to Phys. Rev. Letters.Google Scholar
- 9.Absolute threshold potentials were difficult to determine due to uncertainties in alkali halide surface potentials. Measuring such thresholds would enable us to correlate our results with the recent Auger decay ESD theory, see Refs. 11–13.Google Scholar
- 15.R. Kelly, S. Dzioba, N. H. Tolk and J. C. Tully, To be published in Surface Science.Google Scholar