EXCITED STATE PROTON TRANSFER IN JET COOLED 2,5-di-2-BENZOXAZOLYLPHENOL
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Date
1998
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Publisher
Ohio State University
Abstract
The molecule 2,5-di-2-benzoxazolylphenol (DBP) has been studied by means of laser spectroscopy in a supersonic free jet. In the jet condition the overall, largely Stokes shifted fluorescence occurs exclusively from the proton transferred species. The fluorescence excitation spectrum of DBP exhibits the broad fluorescence background underlying some weak, sharp features. The first prominent band has been observed at $27830 cm^{-1}$, but already at about $250 cm^{-1}$ above the origin the spectrum becomes congested and broad. The origin of OH/OD substituted DBP is blue shifted by $103 cm^{-1}$. For deuterated DBP the resolved line structure in the fluorescence excitation spectrum has been recorded up to the excess energy of $500 cm^{-1}$. To identify spectral features corresponding to deuterated DBP and other species (complexes, non-deuterated sample, isomers) the double-resonance depletion spectroscopy has been applied. Deuteration leads to the narrowing of the bands of the excitation spectrum of DBP. From the analysis of the width of the vibronic bands of DBP, we have estimated an upper limit of the excited state proton transfer rate constant, $k_{PT} = 5.6\times 10^{11} s^{-1}$.
Description
Author Institution: Institute of Physical Chemistry of the Polish Academy of Sciences; Department of Chemistry, Philadelphia College of Pharmacy and Science