On cooling of vibrationally excited benzene molecules in supersonic molecular beams

Photoionisation spectra of the `hotʹ 601 102 1611 and 610 103 bands of the benzene molecule were used to estimate the rotational temperature of benzene in He, Ne, Ar, Kr, N2, or CH4 buffer gas, cooled in a supersonic molecular beam. All the temperature estimates fall within the 4.5–19 K range. For the 61 10 level, the vibrational angular momentum of the degenerate 61 10 state was found to play a significant role in system cooling.