Details

Autor(en) / Beteiligte

• Vester, Peter
• Kubicek, Katharina
• Alonso-Mori, Roberto
• Assefa, Tadesse
• Biasin, Elisa
• Christensen, Morten
• Dohn, Asmus O.
• van Driel, Tim B.
• Galler, Andreas
• Gawelda, Wojciech
• Harlang, Tobias C. B.
• Henriksen, Niels E.
• Kjær, Kasper S.
• Kuhlman, Thomas S.
• Németh, Zoltán
• Nurekeyev, Zhangatay
• Pápai, Mátyás
• Rittman, Jochen
• Vankó, György
• Yavas, Hasan
• Zederkof, Diana B.
• Bergmann, Uwe
• Nielsen, Martin M.
• Møller, Klaus B.
• Haldrup, Kristoffer
• Bressler, Christian

Titel

Tracking structural solvent reorganization and recombination dynamics following e− photoabstraction from aqueous I− with femtosecond x-ray spectroscopy and scattering

Ist Teil von

• The Journal of chemical physics, 2022-12, Vol.157 (22), p.224201-224201

Ort / Verlag

United States: American Institute of Physics

Erscheinungsjahr

2022

Link zum Volltext

Quelle

American Institute of Physics (AIP) Journals

Beschreibungen/Notizen

• We present a sub-picosecond resolved investigation of the structural solvent reorganization and geminate recombination dynamics following 400 nm two-photon excitation and photodetachment of a valence p electron from the aqueous atomic solute, I−(aq). The measurements utilized time-resolved X-ray Absorption Near Edge Structure (TR-XANES) spectroscopy and X-ray Solution Scattering (TR-XSS) at the Linac Coherent Light Source x-ray free electron laser in a laser pump/x-ray probe experiment. The XANES measurements around the L1-edge of the generated nascent iodine atoms (I0) yield an average electron ejection distance from the iodine parent of 7.4 ± 1.5 Å with an excitation yield of about 1/3 of the 0.1M NaI aqueous solution. The kinetic traces of the XANES measurement are in agreement with a purely diffusion-driven geminate iodine–electron recombination model without the need for a long-lived (I0:e−) contact pair. Nonequilibrium classical molecular dynamics simulations indicate a delayed response of the caging H2O solvent shell and this is supported by the structural analysis of the XSS data: We identify a two-step process exhibiting a 0.1 ps delayed solvent shell reorganization time within the tight H-bond network and a 0.3 ps time constant for the mean iodine–oxygen distance changes. The results indicate that most of the reorganization can be explained classically by a transition from a hydrophilic cavity with a well-ordered first solvation shell (hydrogens pointing toward I−) to an expanded cavity around I0 with a more random orientation of the H2O molecules in a broadened first solvation shell.