S. Druzhinin, A. Demeter, V. Galievsky
Oct 9, 2003
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0
Influential Citations
39
Citations
Journal
Journal of Physical Chemistry A
Abstract
With 4-(dimethylamino)benzonitrile (DMABN), 4-(methylamino)benzonitrile (MABN), and 4-aminobenzonitrile (ABN) in an alkane solvent such as n-hexadecane, the fluorescence decay time τ and quantum yield Φf strongly decrease with increasing temperature. For DMABN in n-hexadecane, τ decreases from 3.43 ns at 25 °C to 0.163 ns at 284 °C, with a simultaneous drop in Φf from 0.14 to 0.006. Similar results are obtained for MABN and ABN. By measuring τ, Φf, and the intersystem crossing (ISC) yield ΦISC of the three aminobenzonitriles as a function of temperature in 2-methylpentane and n-hexadecane, covering a range from −151 to 284 °C, the rate constants for internal conversion (IC), ISC, and fluorescence are determined, together with their activation energies and preexponential factors. It is so established that DMABN, MABN, and ABN undergo efficient thermally activated IC. Upon increasing the temperature for DMABN in n-hexadecane from 18 to 287 °C, the IC yield ΦIC increases from 0.04 to 0.95. This goes at the e...