Determination of intermolecular energy transfer by time resolved CARS measurements

Energy transfer in methyl isocyanide following i.r. multiphoton excitation has been examined with a CARS probe. Results show that CARS is an effective technique both for measuring the fraction of molecules receiving energy from the laser and for monitoring intermolecular energy transfer following laser irradiation. In addition, the Raman transition at 2169 cm −1 shows a vibrational progression due to hot bands of the ν 8 bend. Since the ν 8 , bend is the only low energy mode of the molecule, it is an effective vibrational “thermometer”. Utilizing this thermometer, results show that the vibrational state distribution does not fit a Boltzmann distribution for 7 μs following i.r. multiphoton excitation.