Internal, hydrogen bonded OH groups of ethanol oligomers (solvent CCl4) are vibrationally excited by intense picosecond pulses at 3320 cm−1. The transient band shape observed in the OH stretching region (3000 to 3700 cm−1) is monitored by an independently tunable picosecond infrared pulse. The bands in this region are direct probes of hydrogen bridges. The time dependent growth and decay of these bands provides strong evidence for rapid bond breaking with a vibrational predissociation time of ≊5 ps, and for partial reassociation with a time constant of ≊20 ps.

HCO+v, 430 (100) 751" 890d "Reference 10. 6Reference 11. "Reference 12. ''Reference 13. excitation are expected. Since hot bands have not been observed for HCO+, its Tv has been assumed to be the same as that observed for HN2+; this assumption is supported by the similarity in their measured rotational temperatures and in their vibrational frequencies. From the 7r and 7V measurements, Zr~' and Zv"* were calculated by using the standard equations8 and used to determine R¡f, and subsequently Sv°.