Identification of valence electronic states of aqueous acetic acid in acid–base equilibrium using site-selective X-ray emission spectroscopy

Abstract

Occupied valence electronic structures in the neutral and the anionic forms of aqueous acetic acid and their pH dependence under ambient condition are identified for the first time exploiting the site-selectivity of resonant X-ray emission spectroscopy (XES) in combination with calculation based on density functional theory (DFT).

Ionic Solutions Probed by Resonant Inelastic X-ray Scattering

“…In detail, the pre pre-edge peak is assigned to the O C=O ( * ← 1s) transition [47,48]. The emission signal at resonant excitiation energy is mainly from the anion.…”

RIXS investigations of liquids, solutions, and liquid/solid interfaces

“…In recent years, synchrotron-based soft X-ray spectroscopies, in particular X-ray absorption spectroscopy (XAS), X-ray emission spectroscopy (XES), and their (resonant) combination (resonant inelastic soft X-ray scattering -RIXS), have developed into versatile tools to study the electronic structure of liquids and solutions under ambient conditions (see, e.g., [1][2][3][4][5][6][7][8][9][10][11][12][13]). These investigations are made possible by the development of sophisticated experimental setups that overcome the conflict between the high vapor pressure of the studied liquids and the ultra-high vacuum (UHV) requirements of the experimental station.…”

“…and subsequent high-resolution XES measurements gave rise to a vivid discussion of the interpretation of the spectral features either being mainly indicative for different hydrogen bonding configurations [22,[25][26][27][28] or being mainly caused by dissociation processes occurring in the core-excited water molecule [5,7,29,30]. Besides pure liquid systems like water [2,[5][6][7]22,25,26,[31][32][33], methanol [34], or acetic acid [12], a variety of solutions [8][9][10][11]31,35] have been investigated in the past using RIXS, typically focusing on the relative arrangement of solute and solvent as well as their interaction.…”

Triple-path collector optics for grazing incident x-ray emission spectrometer

“…24 In earlier studies we constructed slit-less x-ray emission spectrometers using VLS grating and charge coupled device (CCD) detectors, 25,26 and used them to study adsorbates, 5 liquids, [27][28][29][30] and solutions. [7][8][9] Although recent development trends for x-ray emission spectrometers have focused on improvement of the energy resolution, our developments are focused on increasing the detection efficiency to achieve high reproducibility of spectra. This would allow potential use of XES as an elementand site-selective analytical method, as we demonstrated recently for studying the pH dependence and polarization dependence of acetic acid in solution.…”

“…This would allow potential use of XES as an elementand site-selective analytical method, as we demonstrated recently for studying the pH dependence and polarization dependence of acetic acid in solution. 8,9 In this paper, a new type of collector optics was developed to improve the detection efficiency of grazing incident x-ray emission spectrometer. The optics setup was named trident-optics after its three optical paths that were used to gain higher throughput using two mirrors.…”