OBSERVATION AND SPECTROSCOPY OF HIGH-LYING STATES OF THE CAOH RADICAL- EVIDENCE FOR A BENT, COVALENT STATE

The CaOH radical has been produced in a supersonic molecular beam by t he reaction of water vapor with laser desorbed calcium. Three new elec tronic states, the D (2) Sigma(+), E (2) Sigma(+), and F states have b een observed by laser induced fluorescence and resonance enhanced mult iphoton ionization spectroscopy. The D and E states are linear, but th e F state is bent, the first bent and strongly covalent state of CaOH to be observed. Vibrational constants for the D state have been determ ined and a partially rotationally resolved spectrum has provided the r otational constant and Ca-OH bond length in this state. The D and E st ates are more strongly bound;than the ground state, perhaps indicating some covalent contribution to the bonding. Additional vibrational con stants of the ground electronic state including the CaO-H vibrational frequency have been determined from the emission spectra. (C) 1996 Ame rican Institute of Physics.