Revisiting the Intersystem Crossing in Benzophenone

Date

Mar 25, 2013

Time

2:00 PM - 3:00 PM

Speaker

Dumitru-Claudiu Sergentu

Affiliation

Zernike Institute for Advanced Materials, Univ. of Groningen

Language

en

Main Topic

Materialien

Other Topics

Materialien, Physik

Host

Grit Rötzer

Description

The highly efficient triplet population of benzophenone is one of the most intriguing problems in Photochemistry and a very important photophysical process within the field of Organic Chemistry. The relaxation mechanism of its photoexcited S1 (n-Pi*) state has been intensively studied in the last decade by time-resolved absorption techniques. However, different conclusions have been stated and no theoretical calculations have been able to clearly support one of them. It is known that after photoexcitation to its excited S1 (n-Pi*) state, benzophenone efficiently relaxes to its excited T1 state via a spin-orbit coupling driven mechanism. This phenomenon can be observed in single-crystals, in solution, or even in isolated matrices, hence is independent on the environment. Experimental works point relevant paths to the population of the lowest-lying triplet states, after light absorbtion of benzophenone. Since the triplet T1 state is found to have the same (n-Pi*) nature, a direct transition from the singlet S1 is forbidden by El Sayed rules. Recent experiments support the presence of a second triplet state of p-p* character as a key intermediate in the population of the lowest-lying T1 state.[1] In order to describe the mechanism for the efficient triplet population in benzophenone, we have started ab initio quantum-chemical calculations using the CASSCF/CASPT2 approach. Energy path (MEP) computations, optimizations of Conical Intersections (CIs) and singlet-triplet crossings (STCs), are used in order to identify the most relevant paths to population of the lowest-lying triplet states after light absorbtion of benzophenone. References [1]Aloïse S, Ruckebusch C, Blanchet L, Réhault J, Buntinx G, Huvenne JP, J. Phys. Chem. A, 2008, 112 (2), pp 224–231, DOI: 10.1021/jp075829f.

Links

• Seminars at the IFW

Last modified: Mar 25, 2013, 8:49:10 AM