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Monitoring excited-state relaxation in a molecular marker in live cells–a case study on astaxanthin
2021, Yang, Tingxiang, Chettri, Avinash, Radwan, Basseem, Matuszyk, Ewelina, Baranska, Malgorzata, Dietzek, Benjamin
Small molecules are frequently used as dyes, labels and markers to visualize and probe biophysical processes within cells. However, very little is generally known about the light-driven excited-state reactivity of such systems when placed in cells. Here an experimental approach to study ps time-resolved excited state dynamics of a benchmark molecular marker, astaxanthin, in live human cells is introduced. © The Royal Society of Chemistry 2021.
Excited-state relaxation of hydrated thymine and thymidine measured by liquid-jet photoelectron spectroscopy: experiment and simulation
2015, Buchner, Franziska, Nakayama, Akira, Yamazaki, Shohei, Ritze, Hans-Hermann, Lübcke, Andrea
Time-resolved photoelectron spectroscopy is performed on thymine and thymidine in aqueous solution to study the excited-state relaxation dynamics of these molecules. We find two contributions with sub-ps lifetimes in line with recent excited-state QM/MM molecular dynamics simulations (J. Chem. Phys.2013, 139, 214304). The temporal evolution of ionization energies for the excited ππ* state along the QM/MM molecular dynamics trajectories were calculated and are compatible with experimental results, where the two contributions correspond to the relaxation paths in the ππ* state involving different conical intersections with the ground state. Theoretical calculations also show that ionization from the nπ* state is possible at the given photon energies, but we have not found any experimental indication for signal from the nπ* state. In contrast to currently accepted relaxation mechanisms, we suggest that the nπ* state is not involved in the relaxation process of thymine in aqueous solution.