HIGH RESOLUTION SINGLE AND MULITPHOTON IONIZATION PHOTOELECTRON SPECTROSCOPY

Abstract

Angle resolved, high resolution (8 meV) photoelectron spectroscopy using polarized, rare-gas-radiation combined with linearly-and circularly-polarized dye-laser beams $(\lambda = 800nm to 200 nm)$ has been studied for effusive and pulsed-nozzle beams of NO, CBrClFH, and triethylamine (TEA). These molecules were chosen to illustrate the capabilities of the combined radiation sources and the position-sensitive-detection-based, spherical electron spectrometer (10 cm mean radius). Laser photoionization of TEA through the Rydberg $S_{1}$ and $S_{2}$ states confirms the existence of a rapid internal conversion process to $S_{1}$, from which ionziation proceeds. Using one-photon (HeI) light, the adiabatic and vertical ionization potentials of TEA were defined to be 7.48 eV and 8.24 eV, respectively, which combined with the measured energy of ejected electrons via MPI, put the $S_{1}$ level at 4.75 eV above $S_{o}$. Accurate calibration of the energy scale for the laser MPI PES of TEA was established using the one-photon PES of the ${^{2}\Sigma_{g}}^{+}$ state of $O_{2}$. Photoionzation studies of CBrClFH are preliminary to circular dichroism measurements on the separated enantiomers. Studies of the HeI PES of rotationally and vibrationally resolved NO in the $A{^{2}\sum^{+}}$ state are in progress.