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>Fluorescence Excitation and Photodecomposition of the First Excited Singlet Cyclobutanone (1A2): A Study of Predissociation of and Collisional Energy Transfer from the Vibronically Selected Species
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Fluorescence Excitation and Photodecomposition of the First Excited Singlet Cyclobutanone (1A2): A Study of Predissociation of and Collisional Energy Transfer from the Vibronically Selected Species
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机译：Fluorescence Excitation and Photodecomposition of the First Excited Singlet Cyclobutanone (1A2): A Study of Predissociation of and Collisional Energy Transfer from the Vibronically Selected Species
Fluorescence emission quantum yields (PHgr;F) from the first excited singlet state of cyclobutanone (CB) in the gas phase have been measured in the exciting wavelength (lgr;ex) range of 3050ndash;3350 Aring; atsim;0.5 Aring;resolution. The value of PHgr;Fat 5 torr issim;0.002abovelgr;exequals;3190 Aring;, but it suffers a sharp decline below this wavelength because of the onset of molecular predissociation, e.g.,PHgr;F4times;10minus;6forlgr;ex3100 Aring;. Fluorescence stabilization phenomena are studied by addition of C3H8up to 2200 torr. A simple kinetic treatment of the data provides (i) the estimated singlet lifetime value (tgr;s) of 10minus;9minus;10minus;12sec below lgr;exequals;3140 Aring;; and (ii) the collision efficiency value ofsim;0.5for the upward transition as well as for the downward transition (of vibrational energy transfer). The primary photochemical transformation mechanism for theCBlpar;S1*rpar;is discussed in light of the new estimated lifetime information.
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