Hydrogen bonding in methanol clusters probed by inner-shell photoabsorption spectroscopy in the carbon and oxygen K-edge regions

Abstract

Hydrogen bonding in methanol clusters has been investigated by using inner-shell photoabsorption spectroscopy and density functional theory (DFT) calculations in the carbon and oxygen K-edge regions. The partial-ion-yield (PIY) curves of H(CH(3)OH)(n)(+) were measured as the soft x-ray absorption spectra of methanol clusters. The first resonance peak in the PIY curves, which is assigned to the sigma*(O-H) resonance transition, exhibits a 1.20 eV blueshift relative to the total-ion-yield (TIY) curves of molecular methanol in the oxygen K-edge region, while it exhibits a shift of only 0.25 eV in the carbon K-edge region. Decreased intensities of the transitions to higher Rydberg orbitals were observed in the PIY curves of the clusters. The drastic change in the sigma*(O-H) resonance transition is interpreted by the change in the character of the sigma*(O-H) molecular orbital at the H-donating OH site due to the hydrogen-bonding interaction.

Infrared Absorption Spectra of Monohydric Alcohols

“…However the mechanism of the diffuse band formation and its structure are still the unsolved problems. e importance of the problems connected with the alcohol clustering and structure and, in particular, with the mechanisms of the diffuse absorption band formation is re�ected in the great number of experimental [1][2][3][4][5][6][7][8][9], theoretical [10][11][12][13][14], and combined works [15][16][17][18][19] published in the recent years.…”

Development and application of in situ/operando soft X-ray transmission cells to aqueous solutions and catalytic and electrochemical reactions

“…The inset shows the schematics of the interactions of methyl groups in methanol molecules with methanol and water molecules. characters, and is related to the HB interaction of OH and CH 3 groups [43,44,155,156]. This peak does not change its energy position so much at different concentrations.…”

“…9 shows O K-edge XAS spectra for methanol-water binary solutions at different concentrations at 25 • C. The '4a 1 ' pre-edge peak of liquid water (534.7 eV) is blue-shifted and broadened by the HB interaction [26]. On the other hand, the pre-edge feature of liquid methanol (534.9 eV) is embedded in the main peak but is similarly blue-shifted from the gas-phase peak [43,44,153,154]. The intensity of the pre-edge region around 535.2 eV decreases as the molar fraction of methanol (X) decreases in the binary solution (CH 3 OH) X (H 2 O) 1−X .…”

“…The XAS spectra are obtained by using the Lambert-Beer formula ln(I 0 /I), in which the transmission signal intensity I 0 is measured for the blank and the transmission signal intensity I is for the liquid sample. The photon energy is calibrated by using the first peak (287.96 eV) of methanol gas [44], the first peak of N 1s → * band (400.84 eV) of N 2 gas [64], and the O 1s → * peak top (530.80 eV) of O 2 gas [65], which are mixed with helium gas in regions (II) and (IV). Fig.…”

“…On the other hand, the C and N K-edge XAS can be used to reveal the local structure of solute molecules in aqueous solutions. For example, in aqueous methanol solutions, the hydrophobic interaction of the methyl group in methanol molecule is revealed in the C K-edge XAS [43][44][45].…”