TY  - JOUR
A1  - Brauer, Hans-Dieter
A1  - Schmidt, Reinhard
A1  - Hammerich, Bruno
T1  - Effects of pressure and temperature on the fluorescence quantum yield of N-methylacridone in solution interpreted in terms of the eyring transition-state theory
T2  - Zeitschrift für Naturforschung, A
N2  - The influence of temperatur and pressure on the fluorescence quantum yield of N-methylacridone (9,10-dihydro-9-oxo-10-methyl-acridine) in toluene in the range of 283-313 K and 1 bar to 2.5 kbar, respectively, has been investigated. Treatment of the data in terms of the Eyring transition-state theory leads to a consistent interpretation of the observed effect. The unusually large increase of the quantum yield with increasing pressure is attributed to a positive volume of activation, ⊿V≠, for the thermally activated S1-T2 intersystem crossing which is known to be the only deactivation process (of the Si-state) competing with fluorescence. Comparison of the values for ⊿H≠, the activation enthalpy of this process, determined at various pressures, indicates a decrease in ⊿H≠ at elevated pressures. Since ⊿H≠ can be associated with the S1-T2 energy gap involved in intersystem crossing, this result further confirms the conclusion that the change in Franck-Condon factors alone cannot account for the decrease in the intersystem crossing rate with increasing pressure.
Y1  - 2014
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/74237
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-742375
SN  - 1865-7109
VL  - 36.1981
IS  - 5
SP  - 489
EP  - 493
PB  - Verlag der Zeitschrift für Naturforschung
CY  - Tübingen
ER  -