Mid-IR spectroscopy of supercritical water: From dilute gas to dense fluid

Nicholas J. Hestand; Steven E. Strong; Liang Shi; J. L. Skinner

doi:10.1063/1.5079232

DLC-coated Substrate for Infrared Absorption Spectroscopy in Supercritical Water

MRS Proceedings ◽

10.1557/opl.2011.199 ◽

2011 ◽

Vol 1309 ◽

Author(s):

Takuji Ube ◽

Takashi Ishiguro

Keyword(s):

Ir Spectroscopy ◽

Zinc Selenide ◽

Supercritical Water ◽

Fused Silica ◽

Diamond Like Carbon ◽

Infrared Absorption Spectroscopy ◽

Coated Substrate ◽

Ft Ir ◽

The Stability ◽

Ft Ir Spectroscopy

ABSTRACTThe stability of several kinds of substrates, such as Corning #1737 glass, fused silica, synthetic silica, water free synthetic silica, zinc selenide, silicon, and diamond like carbon (DLC) coated Si in supercritical water (663K and 25MPa) were examined. Their reaction with the water was evaluated by using Fourier transform infrared (FT-IR) spectroscopy. As a result of the present experiment, it was found that DLC-coated Si is one of the most stable and useful substrates for IR spectroscopy in supercritical water.

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Assessing the properties of supercritical water in terms of structural dynamics and electronic polarization effects

Physical Chemistry Chemical Physics ◽

10.1039/c9cp05610f ◽

2020 ◽

Vol 22 (19) ◽

pp. 10462-10479 ◽

Cited By ~ 3

Author(s):

Philipp Schienbein ◽

Dominik Marx

Keyword(s):

Structural Dynamics ◽

Supercritical Water ◽

Electronic Polarization ◽

Polarization Effects ◽

Dilute Gas ◽

Dense Liquid

Evolution of water's structural dynamics from ambient liquid to supercritical dense liquid-like and dilute gas-like conditions.

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Spatio-temporal correlations in aqueous systems: computational studies of static and dynamic heterogeneity by 2D-IR spectroscopy

Faraday Discussions ◽

10.1039/c4fd00201f ◽

2015 ◽

Vol 177 ◽

pp. 313-328 ◽

Cited By ~ 5

Author(s):

Rikhia Ghosh ◽

Tuhin Samanta ◽

Saikat Banaerjee ◽

Rajib Biswas ◽

Biman Bagchi

Keyword(s):

Dielectric Constant ◽

Ir Spectroscopy ◽

Supercritical Water ◽

Reverse Micelles ◽

Water Molecules ◽

Two Dimensional ◽

Dynamic Heterogeneity ◽

2D Ir ◽

Infra Red ◽

Spatio Temporal

Local heterogeneity is ubiquitous in natural aqueous systems. It can be caused locally by external biomolecular subsystems like proteins, DNA, micelles and reverse micelles, nanoscopic materials etc., but can also be intrinsic to the thermodynamic nature of the aqueous solution itself (like binary mixtures or at the gas–liquid interface). The altered dynamics of water in the presence of such diverse surfaces has attracted considerable attention in recent years. As these interfaces are quite narrow, only a few molecular layers thick, they are hard to study by conventional methods. The recent development of two dimensional infra-red (2D-IR) spectroscopy allows us to estimate length and time scales of such dynamics fairly accurately. In this work, we present a series of interesting studies employing two dimensional infra-red spectroscopy (2D-IR) to investigate (i) the heterogeneous dynamics of water inside reverse micelles of varying sizes, (ii) supercritical water near the Widom line that is known to exhibit pronounced density fluctuations and also study (iii) the collective and local polarization fluctuation of water molecules in the presence of several different proteins. The spatio-temporal correlation of confined water molecules inside reverse micelles of varying sizes is well captured through the spectral diffusion of corresponding 2D-IR spectra. In the case of supercritical water also, we observe a strong signature of dynamic heterogeneity from the elongated nature of the 2D-IR spectra. In this case the relaxation is ultrafast. We find remarkable agreement between the different tools employed to study the relaxation of density heterogeneity. For aqueous protein solutions, we find that the calculated dielectric constant of the respective systems unanimously shows a noticeable increment compared to that of neat water. However, the ‘effective’ dielectric constant for successive layers shows significant variation, with the layer adjacent to the protein having a much lower value. Relaxation is also slowest at the surface. We find that the dielectric constant achieves the bulk value at distances more than 3 nm from the surface of the protein.

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