Matrix spectroscopy of Ag, Ta, W, and Mo trapped in Ar and Xe using a triode sputtering source

Abstract

Atomic species of tungsten, molybdenum, and tantalum were extracted from a triode sputtering source and subsequently trapped in xenon and argon matrices at 10 "K. It is shown that this approach is particularly convenient for matrix isolation spectroscopy of materials which are difficult to vaporize. Good correlation with the gas spectrum is obtained for the strong spectral features. There is evidence that some spectral features are greatly enhanced in the matrix spectra over those in the gas spectra. Using silver/xenon as a prototype system it is shown that a wide range of plasma conditions can be used without aggregation. However, certain plasma conditions are identified which lead to weak spectra of silver dimers. Spectral shifts due to matrix effects are found to be W/Ar = 850 cm-1, W/Xe = 700 cm-' for vi < 37 000 cm-' and 0 cm-1 above, Mo/Ar = 2650 cm-1, Mo/Xe = 1150 cm -1, Ta/Xe = 980 cm-1 for v[ < 33 000 cm ' and - 3230 cm-1 above. In the spectrum of Ta/Xe a remarkable red shift of 3230 cm-1 for energies above 33 000 cm-1 is observed. This is in sharp contrast to the Ta spectrum in argon, where a surprisingly consistent perturbation of approximately 1000 cm-1 to the blue is observed.