This Letter presents a new technique (IR/PIRI) to investigate OH stretching
vibrations of cations. In the IR/PIRI technique the MATI signals obtained
for the electronic origin or a vibrational state of the ion are depleted by
an IR laser if the frequency of the IR laser is in resonance with an OH st
retching vibration of the cation. As an example, the resorcinol molecule is
chosen. Two different isomers of this molecule are investigated. In combin
ation with ab initio calculations and IR depletion spectroscopy performed f
or the electronic ground (S-0) and electronically excited state (S-1) of th
e neutral molecule all OH stretching vibrations of the different isomers in
the S-0, S-1, and D-0 states are interpreted. (C) 1998 Elsevier Science B.
V. All rights reserved.