# DETECTION OF NON-RADIATIVE RELAXATION CHANNELS IN ELECTRONICALLY EXCITED MOLECULES USING OPTOTHERMAL DETECTION

Please use this identifier to cite or link to this item: http://hdl.handle.net/1811/13017

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 Title: DETECTION OF NON-RADIATIVE RELAXATION CHANNELS IN ELECTRONICALLY EXCITED MOLECULES USING OPTOTHERMAL DETECTION Creators: Miller, C. Cameron; Hewett, Kevin B.; Philips, Laura A. Issue Date: 1994 Publisher: Ohio State University Abstract: Optothermal detection has been used to observe non-radiative relaxation channels in aniline, {p}-bromoaniline and {trans}-stilbene. A comparison of aniline and {p}-bromoaniline exemplifies the power of this technique. {p}-Bromoaniline has no detectable fluorescence due to a heavy atom effect which increases the rate of intersystem crossing to the triplet state. An optothermal detection spectrum of {p}-bromoaniline was observed with the origin at $32625 cm^{-1}$. For {trans}-stilbene the differences between the laser excitation spectrum and the optothermal detection spectrum of the $S_{1}$ state clearly show the onset of isomerization at $1100-1200 cm^{-1}$ above the origin. Relative quantum yields of fluorescence and Franck-Condon factors have been obtained for a series of vibronic transitions. For low energy vibrational states there is good agreement between the current study and previous work. For vibrational energies above the barrier of isomerization the predicted relative quantum yields do not agree with our experimental results. Our results show that the Frank-Condon factors are more important in the loss of fluorescence intensity than previously reported. Description: Author Institution: Department of Chemistry, Cornell University URI: http://hdl.handle.net/1811/13017 Other Identifiers: 1994-FC-08