Knowledge Bank

Cavity ring-down (CRD) measurements have been made on the $S1(A~ 1B2)\leftarrow S0(X~ 1A1)$ absorption spectrum of slit jet-cooled phenylacetylene (PA) in the 279 nm region as a further investigation of the photophysical properties of PA reported by Hosftein et al., 1195 (2008)} The intensities in the new CRD data are compared with those obtained in the old REMPI experiments, and computational models., 8262 (2010)} The results show that the strong bands in the REMPI spectrum are attenuated while the weak bands ($a1$ modes) remained the same when compared to CRD spectra. The comparison of the simulated spectrum to the CRD and REMPI spectra were satisfactory for most part when the $a1$ modes were scaled up by a factor of 3.24 and 3.55, respectively, giving evidence of some possible theoretical artifacts. The temperature of the slit jet-cooled PA was found to be in the range of $30\pm 5$K by comparison with simulations of the rotational structure of the band origin of the $S1\leftarrow S0$ transition. Additionally, many hot bands located near the band origin of the this transition have been assigned.