The rate of intramolecular vibrational energy relaxation of the fundamental C–H stretch in (CF3)3C–C≡C–H

The high resolution spectrum of the fundamental C–H stretch in (CF3)3C–C≡C–H has been measured using optothermal detection of a collimated molecular beam. Only the Q branch was resolvable and was fit to a Lorentzian with a full width at half maximum of 2.76 GHz, corresponding to an IVR lifetime of 60 ps. The decrease in lifetime in comparison to (CH3)3C–C≡C–H is thought to be due to strong mixing between the C–F stretches and bends and the backbone C–C stretches and bends.