| Abstract: | Rate constants for the dissociation of highly vibrationally excited ketene (CH(2)CO) have been measured at the threshold for the production of CH(2)((3)B(1)) and CO((1)Sigma(+)). The rate constant increases in a stepwise manner with increasing energy, consistent with the long-standing premise that the rate of a unimolecular reaction is controlled by flux through quantized transition-state thresholds. The data give the energies of the torsional and C-C-O bending vibrations of the transition state. |
