VIBRATIONAL POPULATION AND RELAXATION IN IONS AND NEUTRAL MOLECULES

Abstract

We have recently demonstrated that tunable laser excitation is a powerful tool for spectroscopic studies of molecular ions. Selective excitation of single vibrational and rotational levels permits one also to study the dynamics of relaxation processes. We produce a variety of molecular ions and metsatable species by energy transfer or Penning ionization reactions with metastable rare gas atoms. The laser excitation technique permits us to study the nascent vibrational distribution and/or vibrational relaxation processes. $A^{3}\Sigma N_{2}$ is formed and survives on the millisecond time scale in a nonthermal vibrational distribution. The observed vibrational lifetimes range from that of $A^{2}\Pi CO^{+}$ where relaxation competes with its radiative lifetime to $a^{3}\Sigma$ He which remains vibrationally hot for tens of milliseconds at several Torr pressure.