Binding energy of solvated electrons and retrieval of true UV photoelectron spectra of liquids

Abstract

The electronic energy and dynamics of solvated electrons, the simplest yet elusive chemical species, is of interest in chemistry, physics, and biology. Here, we present the electron binding energy distributions of solvated electrons in liquid water, methanol, and ethanol accurately measured using extreme ultraviolet (EUV) photoelectron spectroscopy of liquids with a single-order high harmonic. The distributions are Gaussian in all cases. Using the EUV and UV photoelectron spectra of solvated electrons, we succeeded in retrieving sharp electron kinetic energy distributions from the spectra broadened and energy shifted by inelastic scattering in liquids, overcoming an obstacle in ultrafast UV photoelectron spectroscopy of liquids. The method is demonstrated for the benchmark systems of charge transfer to solvent reaction and ultrafast internal conversion of hydrated electron from the first excited state.

Comment on “Is the Hydrated Electron Vertical Detachment Genuinely Bimodal?”

“…The recent work of Suzuki and coworkers [3,4] shows experimentally that the genuine binding energy spectrum for excitations in the XUV (27.9 and 29.45 eV [3]) is indeed Gaussian. The genuine binding energy spectrum, however, depends on both the initial and the final state of the photoionization transition.…”

“…Note that the "retrieval method" in refs. [3,4] does not allow to deduce the genuine band shape either. It just makes the ad-hoc assumption that the band shape is independent of the excitation energy.…”

Simulating the Ghost: Quantum Dynamics of the Solvated Electron

“…Solvated electron, e − (aq) [2] has been attracting attention of both experimental and theoretical research for more than half a century [3][4][5][6][7]. Understanding its behavior has fundamental implications for electrochemistry, photochemistry and high-energy chemistry, as well as for biology: the non-equilibrium precursor of e − (aq) is responsible for radiation damage to DNA [8].…”

Arresting doubly excited electronic state mediating lightning speed ring-opening reaction of 1,3-cyclohexadiene

“…The XUV pulses were produced using high-harmonic generation in Kr gas with the second harmonic (2ω, 0.29 mJ) of the Ti:sapphire laser as a driving pulse. 28 The 2ω laser pulses were produced with a 0.3-mm thick beta barium borate (BBO) crystal, and focused into a Kr gas cell using a quartz lens (f = 500 mm). The 14th order (14ω: 57 nm, 21.7 eV) single harmonic was selected with a grating-based time-preserving monochromator.…”

“…To this end, we employ ultrafast photoelectron spectroscopy using deep UV (DUV; 267.5 nm, 4.6 eV, 28 fs) pump and extreme UV (XUV; 57 nm, 21.7 eV, 43 fs) probe pulses. 28 Since XUV radiation ionizes all chemical species involved in the reaction, XUV photoelectron spectroscopy enables complete observation from the Franck-Condon region in the 1 1 B state of CHD until the final states of the reaction products. While XUV radiation produced by high-harmonic generation (HHG) 29,30,31,32 has been employed in ultrafast spectroscopy; 32,33,34 experiments with DUV pump pulses are scarce owing to the technical difficulties in generating ultrashort DUV pulses.…”