Time-resolved photoelectron spectroscopy of organic molecules in aqueous solutions

Hummert, Johan; Reitsma, Geert; Mayer, Nicola; Ikonnikov, Evgenii; Eckstein, Martin; Kornilov, Oleg

doi:10.1051/epjconf/201920509027

Cited by 1 publication

(1 citation statement)

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“…However, TAS often meets with considerable difficulty with regard to interpretation of the experimental results owing to significant overlaps of signals associated with excited-state absorption, stimulated emission, and ground-state bleach. Time-resolved photoelectron spectroscopy (TRPES) of liquids is largely free from such complexities, and it offers an alternative approach to studying electronic dynamics in solutions. − TRPES creates a nonstationary state in the excited electronic state of a solute and interrogates its time evolution based on photoemission induced by delayed probe pulses. Dynamical information is extracted from the electron kinetic energy (eKE) distribution measured for photoelectrons emitted from the liquid surface.…”

Section: Introductionmentioning

confidence: 99%

Distortion Correction of Low-Energy Photoelectron Spectra of Liquids Using Spectroscopic Data for Solvated Electrons

Yamamoto

Suzuki

2023

J. Phys. Chem. A

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Time-resolved photoelectron spectroscopy (TRPES) enables realtime observation of ultrafast electronic dynamics in solutions. When extreme ultraviolet (EUV) probe pulses are employed, they can ionize solutes from all electronic states involved in the dynamics. However, EUV pulses also produce a strong ionization signal from a solvent that is typically 6 orders of magnitude greater than the pump−probe photoelectron signal of solutes. Alternatively, UV probe pulses enable highly sensitive and selective observation of photoexcited solutes because typical solvents such as water are transparent to UV radiation. An obstacle in such UV-TRPES measurements is spectral distortion caused by electron scattering and a yet to be identified mechanism in liquids. We have previously proposed the spectral retrieval (SR) method as an a posteriori approach to removing the distortion and overcoming this difficulty in UV-TRPES; however, its accuracy has not yet been verified by comparison with EUV-TRPES results. In the present study, we perform EUV-TRPES for charge transfer reactions in water, methanol, and ethanol, and verify SR analysis of UV-TRPES. We also estimate a previously undetermined energy-dependent intensity factor and expand the basis sets for SR analysis. The refined SR method is employed for reanalyzing the UV-TRPES data for the formation and relaxation dynamics of solvated electrons in various systems. The electron binding energy distributions for solvated electrons in liquid water, methanol, and ethanol are confirmed to be Gaussian centered at 3.78, 3.39, and 3.25 eV, respectively, in agreement with Nishitani et al. [Sci. Adv. 2019, 5(8), eaaw6896]. An effective energy gap between the conduction band and the vacuum level at the gas−liquid interface is estimated to be 0.2 eV for liquid water and 0.1 eV for methanol and ethanol.

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