Probing the Structural Evolution of the Hydrated Electron in Water Cluster Anions (H2O)n-, n ≤ 200, by Electronic Absorption Spectroscopy.
- Author(s): Herburger, Andreas;
- Barwa, Erik;
- Ončák, Milan;
- Heller, Jakob;
- van der Linde, Christian;
- Neumark, Daniel M;
- Beyer, Martin K
- et al.
Published Web Locationhttps://doi.org/10.1021/jacs.9b10347
Electronic absorption spectra of water cluster anions (H2O)n-, n ≤ 200, at T = 80 K are obtained by photodissociation spectroscopy and compared with simulations from literature and experimental data for bulk hydrated electrons. Two almost isoenergetic electron binding motifs are seen for cluster sizes 20 ≤ n ≤ 40, which are assigned to surface and partially embedded isomers. With increasing cluster size, the surface isomer becomes less populated, and for n ≥ 50, the partially embedded isomer prevails. The absorption shifts to the blue, reaching a plateau at n ≈ 100. In this size range, the absorption spectrum is similar to that of the bulk hydrated electron but is slightly red-shifted; spectral moment analysis indicates that these clusters are reasonable model systems for hydrated electrons near the liquid-vacuum interface.