Exploring the ultrafast and isomer-dependent photodissociation of iodothiophenes via site-selective ionization

Weronika O. Razmus; Felix Allum; James Harries; Yoshiaki Kumagai; Kiyonobu Nagaya; Surjendu Bhattacharyya; Mathew Britton; Mark Brouard; Philip H. Bucksbaum; Kieran Cheung; Stuart W. Crane; Mizuho Fushitani; Ian Gabalski; Tatsuo Gejo; Aaron Ghrist; David Heathcote; Yasumasa Hikosaka; Akiyoshi Hishikawa; Paul Hockett; Ellen Jones; Edwin Kukk; Hiroshi Iwayama; Huynh V. S. Lam; Joseph W. McManus; Dennis Milesevic; Jochen Mikosch; Shinichirou Minemoto; Akinobu Niozu; Andrew J. Orr-Ewing; Shigeki Owada; Daniel Rolles; Artem Rudenko; Dave Townsend; Kiyoshi Ueda; James Unwin; Claire Vallance; Anbu Venkatachalam; Shin-ichi Wada; Tiffany Walmsley; Emily M. Warne; Joanne L. Woodhouse; Michael Burt; Michael N. R. Ashfold; Russell S. Minns; Ruaridh Forbes

doi:10.1039/D3CP06079A

Exploring the ultrafast and isomer-dependent photodissociation of iodothiophenes via site-selective ionization†

Weronika O. Razmus,^a Felix Allum,

^bcd James Harries,^e Yoshiaki Kumagai,

^f Kiyonobu Nagaya,^g Surjendu Bhattacharyya,^h Mathew Britton,^c Mark Brouard,

^b Philip H. Bucksbaum,^c Kieran Cheung,^b Stuart W. Crane,

ⁱ Mizuho Fushitani,

^j Ian Gabalski,

^cl Tatsuo Gejo,^k Aaron Ghrist,

^cdl David Heathcote,

^b Yasumasa Hikosaka,

^m Akiyoshi Hishikawa,

^jn Paul Hockett,

^o Ellen Jones,^b Edwin Kukk,^p Hiroshi Iwayama,^q Huynh V. S. Lam,

^h Joseph W. McManus,

^b Dennis Milesevic,

^b Jochen Mikosch,^r Shinichirou Minemoto,^s Akinobu Niozu,^t Andrew J. Orr-Ewing,

^u Shigeki Owada,^vw Daniel Rolles,

^h Artem Rudenko,^h Dave Townsend,

ⁱ Kiyoshi Ueda,^xy James Unwin,^b Claire Vallance,

^b Anbu Venkatachalam,

^h Shin-ichi Wada,

^t Tiffany Walmsley,

^b Emily M. Warne,

^b Joanne L. Woodhouse,

^a Michael Burt,

^b Michael N. R. Ashfold,

^u Russell S. Minns

*^a and Ruaridh Forbes

*^d

Author affiliations

* Corresponding authors

^a School of Chemistry, University of Southampton, Highfield, Southampton, UK
E-mail: r.s.minns@soton.ac.uk

^b Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3TA, UK

^c PULSE Institute, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA

^d Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
E-mail: ruforbes@stanford.edu

^e QST, SPring-8, Kouto 1-1-1, Sayo, Hyogo, Japan

^f Department of Applied Physics, Tokyo University of Agriculture and Technology, Tokyo, Japan

^g Department of Physics, Kyoto University, Kyoto 606-8502, Japan

^h J.R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506, USA

ⁱ Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh, UK

^j Department of Chemistry, Graduate School of Science, Nagoya University, Furo-cho, Chikusa, Nagoya, Aichi 464-8602, Japan

^k Graduate School of Material Science, University of Hyogo, Kuoto 3-2-1, Kamigori-cho, Ako-gun, Hyogo 678-1297, Japan

^l Department of Applied Physics, Stanford University, Stanford, California 94305, USA

^m Institute of Liberal Arts and Sciences, University of Toyama, Toyama 930-0194, Japan

ⁿ Research Center for Materials Science, Nagoya University, Furo-cho, Chikusa, Nagoya, Aichi 464-8602, Japan

^o National Research Council of Canada, 100 Sussex Dr, Ottawa, Canada

^p Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland

^q Institute for Molecular Science, Okazaki 444-8585, Japan

^r Department of Physics, University of Kassel, Heinrich-Plett-Strasse 40, 34132 Kassel, Germany

^s Department of Physics, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan

^t Graduate School of Advanced Science and Engineering, Hiroshima University, Higashi-Hiroshima 739-8526, Japan

^u School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK

^v RIKEN SPring-8 Center, Sayo, Hyogo, Japan

^w Japan Synchrotron Radiation Research Institute, Hyogo, Japan

^x Department of Chemistry, Tohoku University, Sendai 980-8578, Japan

^y Department of Condensed Matter Physics and Photon Science, School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China

Abstract

C–I bond extension and fission following ultraviolet (UV, 262 nm) photoexcitation of 2- and 3-iodothiophene is studied using ultrafast time-resolved extreme ultraviolet (XUV) ionization in conjunction with velocity map ion imaging. The photoexcited molecules and eventual I atom products are probed by site-selective ionization at the I 4d edge using intense XUV pulses, which induce multiple charges initially localized to the iodine atom. At C–I separations below the critical distance for charge transfer (CT), charge can redistribute around the molecule leading to Coulomb explosion and charged fragments with high kinetic energy. At greater C–I separations, beyond the critical distance, CT is no longer possible and the measured kinetic energies of the charged iodine atoms report on the neutral dissociation process. The time and momentum resolved measurements allow determination of the timescales and the respective product momentum and kinetic energy distributions for both isomers, which are interpreted in terms of rival ‘direct’ and ‘indirect’ dissociation pathways. The measurements are compared with a classical over the barrier model, which reveals that the onset of the indirect dissociation process is delayed by ∼1 ps relative to the direct process. The kinetics of the two processes show no discernible difference between the two parent isomers, but the branching between the direct and indirect dissociation channels and the respective product momentum distributions show isomer dependencies. The greater relative yield of indirect dissociation products from 262 nm photolysis of 3-iodothiophene (cf. 2-iodothiophene) is attributed to the different partial cross-sections for (ring-centred) π∗ ← π and (C–I bond localized) σ∗ ← (n/π) excitation in the respective parent isomers.

Physical Chemistry Chemical Physics

Exploring the ultrafast and isomer-dependent photodissociation of iodothiophenes via site-selective ionization†

Abstract

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Exploring the ultrafast and isomer-dependent photodissociation of iodothiophenes via site-selective ionization

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