SHOCK-INDUCED CHANGES AND VIBRONIC ANALYSIS OF THE 1AG-1LA ABSORPTION-BAND OF ANTHRACENE

The vibronic structure of the 1L(a) (or B-1(1u)) absorption band of anthracene in hexane has been examined under shock compression using a time-resolved spectroscopic method. The 1L(a) band shifts toward the red under shock compression, and the rate of the shift decreases monotonically as the pressure increases. Temperature effects of the shift are negligible. The red shift is likely due to dipole and induced-dipole interactions and is caused primarily by densification of the hexane solvent. Shock-induced changes are also analyzed using a simple vibronic analysis that incorporates a single harmonic oscillator model. Pressure-induced changes in the bandwidth, oscillator strength, and excited-state structure are presented.