Knowledge Bank

The rotationally resolved electronic spectrum of the hydrogen bonded $phenol(MeOH)1$ cluster at $35933cm-1$ in a molecular beam is presented. The vibronic origin band consists of two sub-spectra separated by approximately 3.5 GHz, exhibiting an intensity ratio of approximately 16:9, with the weaker band shifted to higher frequencies. Both sub-spectra are ab hybrid bands with an intensity ratio of $Ia/Ib=1/3$. As in $phenol(H2O)1a$ the phenolic moiety acts as proton donor in this cluster system. The observed splitting into sub-bands is attributed to the methyl group internal rotation, however. This differs from $phenol(H2O)1$ that shows a splitting due to a torsional motion of water. From the obtained data we determine parameters of the intermolecular structure of the cluster as well as for the torsional potential of the methyl rotation.