Pulsed-laser photolysis of chromium and molybdenum hexacarbonyls at 308 nm: Simultaneous monitoring of optical and acoustic emissions

C. W. Chan, Nai Ho CHEUNG*

*Corresponding author for this work

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1 Citation (Scopus)

Abstract

An acoustic technique developed earlier was applied to measure the molar number of fragments produced in the XeCl-laser-induced gas-phase photolysis of Cr(CO)6 and Mo(CO)6. The bluish-green Cr and Mo emissions were also monitored and correlated with the acoustic signal. For laser fluence ranging up to about 25 mJ/cm2 (38 mJ/cm2), the Cr (Mo) optical signal varied with laser fluence as y =dx3, in agreement with the model that highly excited metal atoms were produced by direct three-photon processes. The acoustic signal varied with fluence as y = ax + bx2, consistent with the model that most fragments were formed via sequential and direct two-photon processes. Quite expectedly, all coefficients a, b and d vary linearly with carbonyl partial pressure. Both optical and acoustic signals showed onset of saturation at ≈ 25 mJ/cm2 (38 mJ/cm2) for the case of chromium (molybdenum) hexacarbonyl, suggesting that all photolysis channels were equally affected by the depletion of parent molecules. By assuming a common depletion mechanism, upper limits on the branching ratios of the various photolysis channels were estimated.

Original languageEnglish
Pages (from-to)515-523
Number of pages9
JournalApplied Physics B: Lasers and Optics
Volume61
Issue number5
DOIs
Publication statusPublished - Nov 1995

Scopus Subject Areas

  • Physics and Astronomy (miscellaneous)
  • Physics and Astronomy(all)

User-Defined Keywords

  • 81.15
  • 82.40

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