Selective observation of the two oxygen atoms at different sites in the carboxyl group (–COOH) of liquid acetic acid

Abstract

A study of the excitation energy dependence of resonant X-ray emission spectra across the O1s absorption edge in combination with X-ray absorption spectroscopy and density functional theory reveals the site-specific valence electronic structure of liquid acetic acid under ambient conditions.

Probing ion-specific effects on aqueous acetate solutions: Ion pairing versus water structure modifications

“…At an excitation energy of 532.8 eV, the 1s→π* C=O absorption of carboxylate groups can be probed selectively 27,41 . The resulting RIXS spectra shown in Fig.…”

“…In the third step, ion pairing between the same cations and acetate molecules were probed in 1M acetate aqueous solutions by XAS and RIXS. These methods allow a selective probing of the acetate's oxygen since the carboxylate feature is energetically separated from water contribution on the XA spectra 16 and can be excited resonantly to obtain RIXS spectra associated to acetate 27,28 …”

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

“…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.…”

“…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.…”