Transient absorption spectroscopy based on uncompressed hollow core fiber white light proves pre-association between a radical ion photocatalyst and substrate

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Kumar, Ajeet and Malevich, Pavel and Mewes, Lars and Wu, Shangze and Barham, Joshua P. and Hauer, Jürgen (2023) Transient absorption spectroscopy based on uncompressed hollow core fiber white light proves pre-association between a radical ion photocatalyst and substrate. Journal of Chemical Physics, 158 (14). 144201. ISSN 0021-9606 (https://doi.org/10.1063/5.0142225)

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Abstract

We present a hollow-core fiber (HCF) based transient absorption experiment, with capabilities beyond common titanium:sapphire based setups. By spectral filtering of the HCF spectrum, we provide pump pulses centered at 425 nm with several hundred nJ of pulse energy at the sample position. By employing the red edge of the HCF output for seeding CaF2, we obtain smooth probing spectra in the range between 320 and 900 nm. We demonstrate the capabilities of our experiment by following the ultrafast relaxation dynamics of a radical cationic photocatalyst to prove its pre-association with an arene substrate, a phenomenon that was not detectable previously by steady-state spectroscopic techniques. The detected preassembly rationalizes the successful participation of radical ionic photocatalysts in single electron transfer reactions, a notion that has been subject to controversy in recent years.

ORCID iDs

Kumar, Ajeet, Malevich, Pavel, Mewes, Lars, Wu, Shangze, Barham, Joshua P. ORCID logoORCID: https://orcid.org/0000-0003-1675-9399 and Hauer, Jürgen;
CORE (COnnecting REpositories)