Triplet and Singlet (n,π*) Excited States of 4-Pyran-4-one Characterized by Cavity Ringdown Spectroscopy and Quantum-Chemical Calculations.

The 4-pyran-4-one (4PN) molecule serves as a model for investigating structural changes following π* ← n electronic excitation. We have recorded the cavity ringdown (CRD) absorption spectrum of 4PN vapor at room temperature, over the wavelength region from 350 to 370 nm. This spectral region includes the T(n,π*) ← S band system as well as the low-energy portion of the S(n,π*) ← S system.

Cavity Ringdown Spectrum of 2-Cyclohexen-1-one in the CO/Alkenyl CC Stretch Region of the S(n, π*)-S Vibronic Band System.

The 2-cyclohexen-1-one (2CHO) molecule serves as a prototype for understanding the photochemical properties of conjugated enones. We have recorded the cavity ringdown (CRD) absorption spectrum of 2CHO vapor at room temperature over the 360-380 nm range. This portion of the spectrum encompasses the S(n,π*) ← S vibronic band system in the region of the C═C and C═O stretch fundamentals.