Pyrimidine, an Intermediate State Molecule?

W Leo Meerts,W A Majewski

doi:10.1155/lc.5.339

Abstract

The S1(1B1) ← S0(1A1) transition in pyrazine has been investigated. High resolution laser induced fluorescence spectra were obtained by crossing a well collimated molecular beam with UV radiation of an intra‐cavity frequency doubled ring laser. The extreme resolution enabled us to observe the molecular eigenstates of the electronically excited state. Most of the spectral features of the S1 state could be interpreted in terms of a slightly perturbed axis switched rotor spectrum. The perturbations show up both in the energy levels of the S1 and in the intensities of the observed transitions.

Highlights

In the past few years considerable experimental and theoretical progress has been made towards the understanding of the electronic, vibrational and rotational spectra of polyatomic molecules. This progress was powered by high resolution lasers operating in either the ultraviolet, visible, or infrared region of the electromagnetic spectrum
We will demonstrate that structural parameters of near microwave accuracy can be derived from data obtained for electronically excited states
The experimental set-up consists of a single frequency near UV laser combined with laser induced fluorescence (LIF) spectroscopy in a well collimated molecular beam

Summary

INTRODUCTION

In the past few years considerable experimental and theoretical progress has been made towards the understanding of the electronic, vibrational and rotational spectra of polyatomic molecules This progress was powered by high resolution lasers operating in either the ultraviolet, visible, or infrared region of the electromagnetic spectrum. The experimental set-up consists of a single frequency near UV laser combined with laser induced fluorescence (LIF) spectroscopy in a well collimated molecular beam This set-up has been used to obtain spectra with rovibronic resolution. Extra lines are observed in the vicinity of the perturbed lines, which are broadened and/or split in the presence of a field The latter observations will be ascribed to an isolated intersystem crossing (ISC) between the S and a nearly isoenergetic rovibronic level of a lower triplet state (Tl)

EXPERIMENTAL

INTERSYSTEM CROSSING IN PYRAZINE