Cavity ringdown laser absorption spectroscopy and time-of-flight mass spectroscopy of jet-cooled copper silicides

The cavity ringdown technique has been implemented for electronic spectroscopy of jet-cooled CuSi produced in a pulsed UV laser vaporization plasma reactor. A time-of-flight mass spectrometer is used to simultaneously monitor species produced in the supersonic expansion and allows correlation studies to be performed. Seven rotationally resolved vibronic bands have been measured near 400 nm, yielding spectroscopic constants for the ²Σ ground and excited states. Vibronic isotope shifts, together with rotational line positions, permit the unambiguous determination of the spectral carrier and vibronic assignment. Since no ab initio studies for the CuSi molecule exist, a comparison to ab initio studies of the related NiSi molecule is presented. Time-of-flight mass spectrometric measurements indicate the facile formation of Cu_xSi_y, clusters containing multiple copper atoms, in contrast to earlier mass spectrometric work on transition metal suicides.