Reliable absorbance measurement of liquid samples in soft X-ray absorption spectroscopy in transmission mode

Nagasaka, Masanari; Yuzawa, Hayato; Horigome, Toshio; Kosugi, Nobuhiro

doi:10.1016/j.elspec.2017.05.004

Cited by 38 publications

(32 citation statements)

References 44 publications

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“…9,[11][12][13] Recently, we have successfully developed a transmission-type liquid flow cell for XAS of liquid samples in transmission mode, where the liquid layer is sandwiched between two 100 nm thick Si3N4 (or SiC) membranes and the liquid thickness is controllable from 20 to 2000 nm. 4,22,23 In this section, we discuss the details of the XAS measurement system and how to control the liquid thickness for obtaining the appropriate absorbance in XAS spectra. Figure 1 shows an XAS measurement system for liquid samples, 4,22,23 which is settled in the soft X-ray beamline BL3U at UVSOR-III Synchrotron.…”

Section: Xas Of Liquid In Transmission Modementioning

confidence: 99%

Soft X-ray Absorption Spectroscopy of Liquids for Understanding Chemical Processes in Solution

2019

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Soft X-ray absorption spectroscopy (XAS) involving excitation processes of a core electron to unoccupied states is an effective method to study local structures around excited C, N, and O atoms in liquid samples. Since soft X-rays are strongly absorbed by air and liquid itself, we have developed transmission-type liquid flow cells, where the absorbance of liquid samples can be easily reduced and optimized by controlling the liquid thickness. By using the transmission-mode XAS techniques, we have investigated local structures of several liquid samples such as concentration dependence of aqueous pyridine solutions and unexpected temperature-dependent structural changes in liquid benzene from the precise energy shift measurements in XAS spectra with the help of molecular dynamics simulation and inner-shell calculations. These XAS techniques are also applied to in situ/operando observation of chemical processes in solutions such as catalytic and electrochemical reactions.

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Section: Xas Of Liquid In Transmission Modementioning

confidence: 99%

Soft X-ray Absorption Spectroscopy of Liquids for Understanding Chemical Processes in Solution

2019

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“…The relative intensities between main-edge and post-edge of liquid water and crystalline ice Ih are substantially different. 6,[8][9][10][11][20][21][22][23][24] As one of the most qualitative differences, the intensity of main-edge is higher than that of the post-edge in the XAS of liquid water, while the opposite trend is true for the spectra in the ice.…”

Section: Introductionmentioning

confidence: 99%

“…11,18,[20][21][22] Experimentally, the pre-edge feature is present in both liquid water and ice but is more intense in the former. The relative intensities between main-edge and post-edge of liquid water and crystalline ice Ih are substantially different.…”

Section: Introductionmentioning

confidence: 99%

“…[4][5][6][7] Recently, the high-resolution oxygen K-edge core-level spectroscopy, such as X-ray absorption spectra (XAS) and X-ray Raman scattering, has emerged as a powerful experimental technique to probe the electronic structure and infer the molecular structure of water and ice, as well as aqueous solutions. 6,[8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] Excited from the oxygen 1s core level, the electron excitation probes the unoccupied electronic states, which are anti-bonding along the covalent OH bonds and particularly sensitive to the HBs. Therefore, the XAS technique serves as a local probe for the HB structures of liquid water and ice.…”

Section: Introductionmentioning

confidence: 99%

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X-ray absorption of liquid water by advanced ab initio methods

et al. 2017

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Oxygen K-edge X-ray absorption spectra of liquid water are computed based on the configurations from advanced ab initio molecular dynamics simulations, as well as an electron excitation theory from the GW method. One one hand, the molecular structures of liquid water are accurately predicted by including both van der Waals interactions and hybrid functional (PBE0). On the other hand, the dynamic screening effects on electron excitation are approximately described by the recently developed enhanced static Coulomb hole and screened exchange approximation by Kang and Hybertsen [Phys. Rev. B 82, 195108 (2010)]. The resulting spectra of liquid water are in better quantitative agreement with the experimental spectra due to the softened hydrogen bonds and the slightly broadened spectra originating from the better screening model.

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“…Recently, high-resolution X-ray absorption spectroscopy (XAS), has emerged to be a powerful experimental technique to probe the water structure at molecular scale [13][14][15][16][17][18][19]. Allowed by Franck-Condon principle [20], the electrons leaving the oxygen core can be described as excited electronic states from an instantaneously frozen snapshot of water at equilibrium.…”

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X-ray Absorption Spectral Signature of Quantum Nuclei in Liquid Water

Sun¹,

Zheng²,

Chen³

et al. 2018

Preprint

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Based on electron-hole excitation theory, we investigate the X-ray absorption spectral signature of nuclear quantum effect in liquid water, whose molecular structure is simulated by path-integral molecular dynamics using the MB-pol model. Compared to spectra generated from classically modeled water structure, quantum nuclei has important effect on spectra in terms of both the spectral energies and their line shapes. At the short-range ordering of H-bond network, the delocalized protons increase the fluctuations on the intramolecular covalency and broaden the pre-edge of the spectra. For intermediate-range and long-range orderings, the observed red and blue shifts of the main-edge and post-edge are attributed to the so-called competing quantum effects, under which both the weak and well-formed H-bonds are promoted. The theoretical spectra are in nearly quantitative agreement with the available experimental data.The nature of H-bond network in water continues to be at the center of scientific interests [1][2][3][4][5][6][7][8][9][10][11][12]. Recently, high-resolution X-ray absorption spectroscopy (XAS), has emerged to be a powerful experimental technique to probe the water structure at molecular scale [13][14][15][16][17][18][19]. Allowed by Franck-Condon principle [20], the electrons leaving the oxygen core can be described as excited electronic states from an instantaneously frozen snapshot of water at equilibrium. Therefore, XAS spectrum inherits a unique local signature of its molecular environment, complimentary to the scattering experiments [21,22].Ab initio theory is desired for an unambiguous interpretation of the underlying molecular structure. However, theoretical prediction has posed a major challenge by itself. The computed XAS spectrum is sensitive to the accuracy of methods in both the adopted electronic and molecular theories. Rigorously, the electron-hole excitation theories, such as the Bethe-Salpeter equation (BSE) [13,[23][24][25], should be applied beyond the unoccupied electronic structure from density functional theory [26][27][28][29]. However, the BSE is computational formidable and has not yet widely applied in water. The above computational burden has been greatly alleviated by the recently introduced approximate BSE solution utilizing localized basis [30]. On the other hand, the modeling of water at molecular level is no less difficult. The difficulty lies at the complex nature of the H-bond structure balanced by many physical interactions. The directional H-bond, as the building block of the near-tetrahedral structure in water, is much weaker than the ordinary (covalent or ionic) chemical bond. Furthermore, the H-bond network is largely modified by the van der Waals interaction, whose energy is even weaker than H-bond by one order of magnitude [31][32][33][34][35]. Worse still, nuclear quantum effects (NQEs) should be properly considered due to the low mass of proton [36][37][38]. Under the influence of NQEs, the more delocalized protons are found to introduce an unexpected competing e...

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Reliable absorbance measurement of liquid samples in soft X-ray absorption spectroscopy in transmission mode

Cited by 38 publications

References 44 publications

Soft X-ray Absorption Spectroscopy of Liquids for Understanding Chemical Processes in Solution

Soft X-ray Absorption Spectroscopy of Liquids for Understanding Chemical Processes in Solution

X-ray absorption of liquid water by advanced ab initio methods

X-ray Absorption Spectral Signature of Quantum Nuclei in Liquid Water

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