The effect of pressure on the emission of 3hyphen;hydroxyflavone has been studied in isobutanol, glycerol, and two mixtures of these solvents. Below a viscosity of sim;50 P there is an increase in the fraction of emission from the tautomeric state with pressure. At higher viscosities the fraction of tautomeric emission decreased. At viscosities less than sim;50 P the lifetimes obtained from the two emission peaks were the same, indicating that the two excited states were in equilibrium. At higher viscosities, the lifetimes differed, indicating that the distribution was kinetically controlled. In hexamethylnonane (HMN) only tautomer emission was observed even at very high viscosities; also, only tautomer emission occurs in a rigid polyisobutylene film. A few measurements on 7hyphen;hydroxyflavone are briefly discussed.
展开▼
