Laboratory Determination of Astrophysically Important Properties of Diatomic Zirconium-Oxide from Laser Induced Fluorescence and Thermal Emission Spectra.

The astrophysically important molecule ZrO has been studied using a variety of spectroscopic techniques. Oscillator strengths of electronic state transitions and the relative energies of the lowest lying electronic states have been determined. The analysis of an infrared band system has led to the laboratory identification of many of the Wing bands which appear in the spectra of S-type stars. Oscillator strengths were determined from c('3)(PI) state radiative lifetime measurements. Lifetimes were measured by observing fluorescence decay after pulsed laser excitation of the c('3)(PI) -- a('3)(DELTA) transition. An estimate of the ZrO-helium inelastic collision cross section has also been made. The separation of the X('1)(SIGMA)('+) and a('3)(DELTA) states (and thus the singlet-triplet separation) was made by observing c('3)(PI) -- X('1)(SIGMA)('+) intercombination fluorescence during laser excitation of the c('3)(PI) -- a('3)(DELTA) transition. a('3)(DELTA)(,1) was determined to be 1099.08cm('-1) above the ground state, X('1)(SIGMA)+. The energy of the second lowest lying singlet state A('1)(DELTA) was determined to be 5904.19cm('-1) above X('1)(SIGMA)('+), using techniques similar to those of the singlet-triplet experiment. A rotational-vibrational analysis of the B('1)(PI) -- A('1)(DELTA) transition served to verify this result. This transition is the source of many of the Wing bands.