Knowledge Bank

Time dependent intramolecular vibrational relaxation (IVR) in the $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}B2$ excited electronic state of alkylaniline and alkylbenzene molecules was directly monitored by employing a two-photon ionization process. Photoelectrons were produced by two-color pump-probe ionization induced by picosecond laser pulses impinging on a jet-cooled molecular beam. Their kinetic energies of photoelectrons were measured by a time of flight method. With the picosecond pump laser tuned to different vibrational modes in the excited electronic state of these molecules and the probe laser adjusted to the different delay times, photoelectron spectra were recorded. The extended chain conformation (trans) and the coiled chain conformation (gauche) exhibit remarkably different IVR behavior. Comparison of the rates of IVR in these molecules will be made. The conformational dependence of the ionization potential in these molecules will also be discussed.