A direct comparison of vibrational deactivation of hexafluorobenzene excited by infrared multiple photon absorption and internal conversion

Abstract

<jats:p>We report the first direct comparison between energy transfer parameters measured using infrared multiphoton absorption (IRMPA) versus ultraviolet (UV) excitation followed by rapid internal conversion (IC). Highly excited hexafluorobenzene (HFB) molecules in the electronic ground state were prepared by (i) IRMPA by CO2 laser pumping to an average initial energy of 14 500–17 500 cm−1 and (ii) UV excitation to ∼40 300 cm−1 followed by IC. The vibrational deactivation of the highly excited HFB by the monatomic collider gas argon was monitored by time-resolved infrared fluorescence. The results for the two methods are identical within experimental error, demonstrating the viability of IRMPA as a method of state preparation for vibrational deactivation experiments involving large molecules.</jats:p>