Dynamics of benzene excimer formation from the parallel-displaced dimer

Thiago Messias Cardozo , Andre Pessoa Galliez , Thiago Messias Cardozo , Andre Pessoa Galliez , Itamar Borges (1) , Felix Plasser , Adelia J A Aquino , Mario Barbatti (2) , Hans Lischka (3)

1 IME - Instituto Militar de Engenharia=Military Institute of Engineering
2 ICR - Institut de Chimie Radicalaire
3 Institute for theoretical Chemistry

Excimers play a key role in a variety of excited-state processes, such as exciton trapping, fluorescence quenching, and singlet-fission. The dynamics of benzene excimer formation in the first 2 ps after S1excitation from the parallel-displaced geometry of the benzene dimer is reported here. It was simulated via nonadiabatic surface-hopping dynamics using the second-order algebraic diagrammatic construction (ADC(2)). After excitation, the benzene rings take ~0.5-1.0 ps to approach each other in a parallel-stacked structure of the S1minimum and stay in the excimer region for ~0.1-0.4 ps before leaving due to excess vibrational energy. The S1-S2 gap widens considerably while the rings visit the excimer region in the potential energy surface. Our work provides detailed insight into correlations between nuclear and electronic structure in the excimer and shows that decreased ring distance goes along with enhanced charge transfer and that fast exciton transfer happens between the rings, leading to the equal probability of finding the exciton in each ring after around 1.0 ps.

Keywords: Excimer; Benzene; Dimer; Quenching Factor

Domains: Chemical Sciences

Thiago Messias Cardozo, Andre Pessoa Galliez, Thiago Messias Cardozo, Andre Pessoa Galliez, Itamar Borges, et al.. Dynamics of benzene excimer formation from the parallel-displaced dimer. Physical Chemistry Chemical Physics, 2019. ⟨hal-01965447⟩