EFFECT OF ISOTOPIC-SUBSTITUTION ON THE VISIBLE ABSORPTION-SPECTRUM OF OZONE

Absorption spectra for 16O3 and 18O3 have been recorded to study the vibronic structure of the Chappuis band. The isotope shifts indicate that the strongest features involve transitions to two electronically excited states characterized by adiabatic energies almost-equal-to 750 cm-1 apart, with the higher one near 16 400 cm-1. The vibrational structure can be associated with a relatively simple progression in this higher state (omega-1 and omega-2 almost-equal-to 1210 and 640 cm-1, respectively), and one isolated band associated with the lower state. Alternatively, an autocorrelation analysis indicates major recurrences near 31 and 41 fs for O-16(3) and correspondingly longer times for O-18(3). Minor recurrences at longer times are also present, but all are significantly shorter lived than those associated with the Hartley band. The results are discussed in the context of ab initio calculations and recent experimental and theoretical work involving visible and ultraviolet absorption spectra of ozone.