Zhi-Hong Li

18O/16O isotope effect on the laser fluorescence excitation spectrum of jet-cooled tropolone

Abstract The A 1B2−X 1A1 laser fluorescence excitation spectra of jet-cooled tropolone (18O2H) and tropolone (18O2D) have been measured to investigate 18O/16O isotope effects on the tunneling doublet splitting and the vibrational fundamental for various modes in the A 1B2 state.

Electronic spectra of jet-cooled isopropyltropolones in the S1−S0 region: proton tunneling in the S1 state

Laser fluorescence excitation spectra and dispersed fluorescence spectra of jet‐cooled 3‐, 4‐, and 5‐isopropyltropolone in the S1–S0 region have been measured to investigate the effect of unsymmetrical and symmetrical substitution of an isopropyl group on proton tunneling. The 0++ and 0−+ transitions have been identified in the excitation spectra of 3‐isopropyltropolone and its −OD derivative. The tunneling doublet splittings in the S1 state have been determined to be 58 and 14 cm−1 for normal and deuterated species, respectively. The increase in tunneling splitting of 3‐isopropyltropolone compared with that of tropolone suggests that the substitution of the isopropyl group induces an asymmetry in the double‐minimum potential well. In contrast with the excitation spectrum of 3‐isopropyltropolone, no 0−− and 0−+ transitions have been detected in 4‐ and 5‐isopropyltropolone. The nonobservation of these transitions is likely to be due to substantial increase in the potential‐energy barrier to tunneling in th...