Open AccessUltrafast Relaxation Dynamics of Photoexcited Zinc-Porphyrin: Electronic-Vibrational Coupling
Author(s) -
Baxter Abraham,
Jesus NietoPescador,
Lars Gundlach
Publication year - 2016
Publication title -
the journal of physical chemistry letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.563
H-Index - 203
ISSN - 1948-7185
DOI - 10.1021/acs.jpclett.6b01439
Subject(s) - vibrational energy relaxation , photoexcitation , ultrafast laser spectroscopy , photochemistry , relaxation (psychology) , excited state , chemistry , internal conversion , chemical physics , porphyrin , spectroscopy , tetraphenylporphyrin , atomic physics , spectral line , psychology , social psychology , physics , quantum mechanics , astronomy
Cyclic tetrapyrroles are the active core of compounds with crucial roles in living systems, such as hemoglobin and chlorophyll, and in technology as photocatalysts and light absorbers for solar energy conversion. Zinc-tetraphenylporphyrin (Zn-TPP) is a prototypical cyclic tetrapyrrole that has been intensely studied in past decades. Because of its importance for photochemical processes the optical properties are of particular interest, and, accordingly, numerous studies have focused on light absorption and excited-state dynamics of Zn-TPP. Relaxation after photoexcitation in the Soret band involves internal conversion that is preceded by an ultrafast process. This relaxation process has been observed by several groups. Hitherto, it has not been established if it involves a higher lying "dark" state or vibrational relaxation in the excited S2 state. Here we combine high time resolution electronic and vibrational spectroscopy to show that this process constitutes vibrational relaxation in the anharmonic S2 potential.