Showing papers by "Hirdyesh Mishra published in 1997"
TL;DR: In this paper, the spectral and photophysical properties of salicylic acid in various solvents have been studied by steady state and time resolved experiments, and various emitting species have been identified.
Abstract: The spectral and photophysical properties of salicylic acid in various solvents have been studied by steady state and time resolved experiments. Various emitting species have been identified. In alcohols, e.g. methanol, both the zwitterion and monoanion show emission. The addition of a small amount of acid results only in zwitterionic emission, whereas in the presence of a small amount of alkali, the monoanion is produced. Only the monoanion shows emission in water. In concentrated sulfuric acid, emission from the cation is observed, whereas in concentrated KOH solution, the dianion is the emitting species. In hydrogen bonding solvents, e.g. diethyl ether, hydrogen bonded monomers are present. In polymer matrix poly(methyl methacrylate) only monomeric emission is observed. The deactivation of the cation is similar to that of the zwitterion, indicating that the presence of an extra proton in the carboxylic group increases the nonradiative process. Hydrogen bonding as well as viscosity/rigidity of the matrix have also been found to decrease the deactivation rate in the zwitterion.
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