Continuous Tuning of Intersystem Crossing Times in Rose Bengal Water/Methanol Solutions

authored by
Onno Strolka, Pascal Rauthe, Tim Muschik, Philipp Frech, André Niebur, Andreas N. Unterreiner, Jannika Lauth
Abstract

We use femtosecond transient broadband absorption spectroscopy (TAS) to characterize Rose Bengal in water/methanol solutions and reveal a continuous tunability of intersystem crossing (ISC) times by changing the mole fraction of the solvents. We find that the transients of excited state absorptions (ESAs) in Rose Bengal at ∼430 nm can be attributed to transitions from the singlet state S1, with decay times of 74 ps via ISC in pure water and up to 405 ps in pure methanol. TA measurements at near-infrared wavelengths, on the other hand, reveal the rise of an ESA at ∼1080 nm from the triplet state T1 with time constants of 68 and 491 ps in pure water and methanol, respectively, strongly supporting the associated UV-vis TAS data. Solvent mixtures show a quasi-linear rise of the ISC times with increasing mole fractions of methanol and indicate that Rose Bengal in varying solvent mixtures can be used as a model system to study their influence on excited state photophysics.

Organisation(s)
PhoenixD: Photonics, Optics, and Engineering - Innovation Across Disciplines
Institute of Physical Chemistry and Electrochemistry
External Organisation(s)
University of Tübingen
Karlsruhe Institute of Technology (KIT)
Type
Article
Journal
Journal of Physical Chemistry B
Volume
128
Pages
12189-12196
No. of pages
8
ISSN
1520-6106
Publication date
12.12.2024
Publication status
Published
Peer reviewed
Yes
ASJC Scopus subject areas
Physical and Theoretical Chemistry, Surfaces, Coatings and Films, Materials Chemistry
Electronic version(s)
https://doi.org/10.1021/acs.jpcb.4c07449 (Access: Closed)