Genuine binding energy of the hydrated electron

April 28, 2017

A combined photoelectron study on water droplets and a liquid water microjet reveals for the first time the influence of electron scattering on the binding energy and the photoelectron anisotropy of the hydrated electron

The unknown influence of inelastic and elastic scattering of slow electrons in water has made it difficult to clarify the role of the solvated electron in radiation chemistry and biology. We combine accurate scattering simulations with experimental photoemission spectroscopy of the hydrated electron in a liquid water microjet, with the aim of resolving ambiguities regarding the influence of electron scattering on binding energy spectra, photoelectron angular distributions, and probing depths. The scattering parameters used in the simulations are retrieved from independent photoemission experiments of water droplets. For the ground-state hydrated electron, we report genuine values devoid of scattering contributions for the vertical binding energy and the anisotropy parameter of 3.7 ± 0.1 eV and 0.6 ± 0.2, respectively. Our probing depths suggest that even vacuum ultraviolet probing is not particularly surface-selective. Our work demonstrates the importance of quantitative scattering simulations for a detailed analysis of key properties of the hydrated electron.
 


Fig. 2 Experimental and simulated photoelectron spectra of eaq. Photoelectron kinetic energy distributions for 12 different ionization laser energies 3.6 eV ≤ hν ≤ 13.6 eV. All spectra are normalized to the same maximum intensity. (A) Experimental spectra. (B) Scattering simulations.

Reference:  Luckhaus, D., Y.-i. Yamamoto, T. Suzuki and R. Signorell (2017). Genuine binding energy of the hydrated electron. Sci. Adv. 3. (10.1126/sciadv.1603224) Luckhaus-2017 (377 KB).

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