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Transient x-ray absorption spectroscopy of hydrated halogen atom
Christopher G Elles1, Ilya A Shkrob, Robert A Crowell
1Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439, USA. elles@usc.edu
The Journal of Chemical Physics
|February 20, 2008
Summary
Transient species from aqueous bromide were observed using time-resolved x-ray absorption spectroscopy. The study reveals minimal solvent charge transfer and hydrophobic interactions around the neutral bromine atom.
Area of Science:
- Physical Chemistry
- Spectroscopy
- Chemical Physics
Background:
- Aqueous bromide solutions are relevant in various chemical processes.
- Understanding transient species in solution is crucial for reaction mechanisms.
Purpose of the Study:
- To investigate the transient species formed by electron detachment from aqueous bromide.
- To characterize the electronic structure and solvent interactions of the neutral bromine atom.
Main Methods:
- Time-resolved X-ray absorption spectroscopy (TR-XAS) was employed.
- K-edge spectroscopy was used to probe the electronic transitions of bromine.
- Comparison with Monte Carlo and quantum chemical simulations.
Main Results:
- The K-edge spectrum of the transient Br(0) atom showed a distinct 1s-4p resonance absent in the Br(-) precursor.
- Strong resonance indicated minimal charge transfer from the solvent to the Br(0) atom.
- Weak oscillations above the absorption edge suggested hydrophobic interactions dominate the solvent shell.
Conclusions:
- The neutral bromine atom in water exhibits limited solvent charge transfer.
- Hydrophobic interactions primarily define the solvent shell around the Br(0) atom.
- Simulation results support the experimental findings on solvent structure.
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