Investigation of the Excited State Structure of DCM via Ultrafast Electronic Pump/Vibrational Probe †

Department of Chemistry, University of California, Berkeley, Berkeley, California, United States
The Journal of Physical Chemistry B (Impact Factor: 3.3). 10/2006; 110(38):18989-95. DOI: 10.1021/jp0603738
Source: PubMed


Time resolved visible pump, infrared probe transient absorption measurements of the solutes 4-dicyanomethylene-2-methyl-6-(p-(dimethylamino)styryl)-4H-pyran (DCM) and its isotopomer DCM-d6 are employed to probe the dynamics of charge transfer state formation in dimethyl sulfoxide (DMSO) and acetonitrile (MeCN). We observe a two stage charge transfer (CT): the first step is an instrument-response-limited charge separation to the dicyanomethylene group, and the second involves a structural evolution of the dimethylamino group. Theoretical calculations and isotopic substitution indicate that the observed vibration is due to the dimethylamino group twisting out of plane, stabilizing the charge separation.

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