The surprisingly short vibrational lifetime of the internal stretch of CO adsorbed on Si(100)

Picosecond sum-frequency generation spectroscopy has been employed to study the dynamics of the internal stretch vibration of CO adsorbed on a Si(100) surface. Using the IR pump-sum-frequency generation probe method, the vibrational lifetime of the C-O stretch vibration has been determined to be 2.3 +/- 0.5 ns. Within the experimental error limits, the identical lifetime was observed for (CO)-C-12-O-16 and (CO)-C-13-O-16. No strong dependency on the carrier density in the substrate, inferred from measurements using differently doped crystals, was observed. (C) 2005 American Institute of Physics.