Vibrational Bands Of Water Research Articles

Modification of ATP hydrolysis by Strong Coupling with O−H Stretching Vibration

AbstractPolaritonic chemistry has become an important research field, since vibrational strong coupling (VSC) between molecular transitions and photonic structures was discovered to alter the energy landscape of molecules, through the creation of hybrid states in an optical cavity resonant to a molecular absorption band. ATP hydrolysis is an essential reaction in all known forms of life and have fundamental roles in energy conservation, active transport and pH homeostasis. Herein, using a Fabry‐Pérot (FP) cavity filled with the ATP hydrolysis solution, we measured the ATP hydrolysis efficiency in both strong and weak coupling modes and investigated the VSC effect on the catalytic activity of ATPase at the stretching vibration band of water. We observed an approximately 10‐fold increase of the apparent hydrolysis rate when coupling with the water stretching vibration. This work demonstrates the potential of employing VSC to precisely interfere water‐based biochemical reactions.

Spatial Heterodyne Observations of Water (SHOW) vapour in the upper troposphere and lower stratosphere from a high altitude aircraft: Modelling and sensitivity analysis

A spatial heterodyne spectrometer (SHS) has been developed to measure the vertical distribution of water vapour in the upper troposphere and the lower stratosphere with a high vertical resolution (∼500 m). The Spatial Heterodyne Observations of Water (SHOW) instrument combines an imaging system with a monolithic field-widened SHS to observe limb scattered sunlight in a vibrational band of water (1363 nm–1366 nm). The instrument has been optimized for observations from NASA's ER-2 aircraft as a proof-of-concept for a future low earth orbit satellite deployment. A robust model has been developed to simulate SHOW ER-2 limb measurements and retrievals. This paper presents the simulation of the SHOW ER-2 limb measurements along a hypothetical flight track and examines the sensitivity of the measurement and retrieval approach. Water vapour fields from an Environment and Climate Change Canada forecast model are used to represent realistic spatial variability along the flight path. High spectral resolution limb scattered radiances are simulated using the SASKTRAN radiative transfer model. It is shown that the SHOW instrument onboard the ER-2 is capable of resolving the water vapour variability in the UTLS from approximately 12 km – 18 km with ±1 ppm accuracy. Vertical resolutions between 500 m and 1 km are feasible. The along track sampling capability of the instrument is also discussed.

Measurement of water vapor using an imaging field-widened spatial heterodyne spectrometer.

Spatial heterodyne spectroscopy (SHS) has been successfully applied to measure variations in water vapor pressure in the lab. An imaging system is combined with a monolithic field-widened SHS to observe a white-light source through a 1m length water vapor cell that is designed to produce predictable variations in the water vapor pressure. The performance of the spectrometer design is examined by comparing spectra simulated using a radiative transfer model to observed spectra at several cell pressures. The intended application of the instrument to vertically resolve the water vapor profile in the upper troposphere and lower stratosphere using limb-scattered radiation in a vibrational band of water (1363-1366nm) is also introduced.

Evaluation of pyrolysis characteristics of milled bamboo using near-infrared spectroscopy

This paper reports the development of a rapid and low-cost method based on near-infrared spectroscopy as an alternative for thermogravimetric determination of the pyrolysis characteristics, including Tonset, Tsh, Tpeak, Toffset and DTGpeak, of milled bamboo. Tonset is the extrapolated onset temperature that is calculated from the partial peak resulting from the decomposition of the hemicellulose component, Tsh is the temperature corresponding to the overall maximum of the hemicellulose decomposition rate, DTGpeak is the overall maximum of the cellulose decomposition rate, Tpeak is the temperature corresponding to the overall maximum of the cellulose decomposition rate and Toffset is the extrapolated offset temperature of the DTGpeak curves determined using thermogravimetric analysis (TGA). The models may be used to control the pyrolysis processes of bamboo to achieve the most economical and environmental conditions. 80 samples of bamboo with various circumferences of culms in the ranges of approximately 16–18, 18–20, 20–22, 22–24, 24–26, 26–28, 28–30, 30–32, 32–34, 34–36, 36–38 and 38–40 cm were randomly collected for optimization of the models. The models were optimized by partial least squares regression (PLSR) with 80% of samples for the calibration set and 20% for the validation set. For Tonset, Tsh, Tpeak, Toffset and DTGpeak, the models showed coefficients of determination (R2) of 0.566, 0.845, 0.917, 0.973, and 0.671; root mean square errors of prediction (RMSEP) of 9.7 °C, 4.36 °C, 3.77 °C, 2.66 °C, and 0.428 wt loss %/min; ratios of prediction to deviation (RPD) of 1.52, 2.58, 3.48, 3.55, and 1.75; and biases of −0.344 °C, −0.765 °C, 0.349 °C, −5.41 °C, and 0.045 wt loss %/min, respectively. In addition, the results showed that pyrolysis characteristics did not depend on the circumference. The vibrational bands of water and CH3, OH stretch, first overtones of Ar–OH, CH2 and HCCH in the cellulose and lignin structures, OH hydrogen bonds of polyvinyl alcohol and CH stretch corresponding to the first overtone of CH2 had the highest influence on the values of Tonset, Tsh, Tpeak, and Toffset, respectively. The vibrational band of the COC asymmetrical stretches of cellulose and hemicellulose, and the combination of OH stretch and HOH bend of polysaccharides influenced the DTGpeak value. These results are beneficial for studying the thermal behaviour of milled bamboo as a potential resource for producing biofuels, especially in the pyrolysis process.

Temperature and salinity effects on the Raman scattering cross section of the water OH-stretching vibration band in NaCl aqueous solutions from 0 to 300 °C

Water is often used as an internal standard in quantitative Raman spectroscopic measurements of dissolved species in aqueous solutions containing salts at varying temperatures. However, the effects of temperature and dissolved ions on the relative differential Raman scattering cross section (RSCS) of the OH-stretching vibration band of water at elevated temperatures and salinities are not well defined quantitatively. In this study, the Raman spectra of NaCl solutions with different salinity (from 0 to 5 mol NaCl/kg · H2O) at 20 °C at atmospheric pressure and from 0 to 300 °C at 30 MPa were studied. The relative RSCS of the OH-stretching vibration band of liquid water (σ(mNaCl, T, 30 MPa)/σ(Pure water, 20 °C, 30 MPa)) as a function of temperature (T, in °C) and salinity (mNaCl, in mol/kg · H2O) was established: σmNaCl,T,30MPa/σ(Pure water,20oC,30MPa)=fT,mNaCl=aT−20+b where a = 0.000089 × mNaCl1/2 − 0.001164; b = 0.0355 × mNaCl + 1; The RSCS of the OH-stretching vibration band of water in pseudo back-scattering geometry decreases linearly with increasing temperature, but increases with the addition of dissolved NaCl within the whole temperature range. The enhancement factor of the RSCS by dissolved NaCl increases with temperature. Such effects of temperature and salinity should be considered in quantitative Raman spectroscopic study of species concentration in aqueous solution at high temperature when using water as internal standard. Copyright © 2016 John Wiley & Sons, Ltd.

Water spectral pattern as holistic marker for water quality monitoring

Online water quality monitoring technologies have been improving continuously. At the moment, water quality is defined by the respective range of few chosen parameters. However, this strategy requires sampling and it cannot provide evaluation of the entire water molecular system including various solutes. As it is nearly impossible to monitor every single molecule dissolved in water, the objective of our research is to introduce a complimentary approach, a new concept for water screening by observing the water molecular system changes using aquaphotomics and Quality Control Chart method. This approach can continuously provide quick information about any qualitative change of water molecular arrangement without taking into account the reason of the alteration of quality. Different species and concentrations of solutes in aqueous systems structure the water solvent differently. Aquaphotomics investigates not the characteristic absorption bands of the solute in question, but the solution absorption at vibrational bands of water's covalent and hydrogen bonds that have been altered by the solute. The applicability of the proposed concept is evaluated by monitoring the water structural changes in different aqueous solutions such as acid, sugar, and salt solutions at millimolar concentration level and in ground water. The results show the potential of the proposed approach to use water spectral pattern monitoring as bio marker of water quality. Our successful results open a new venue in water quality monitoring by offering a quick and cost effective method for continuous screening of water molecular arrangement. Instead of the regular analysis of individual physical or chemical parameters, with our method – as a complementary tool – the structural changes of water molecular system used as a mirror reflecting even small disturbances in water can indicate the necessity of further detailed analysis by conventional methods.

Liquid phase temperature determination in dense water sprays using linear Raman scattering

Linear Raman scattering has been applied for the determination of the temperature of the liquid phase in water sprays under normal and superheated conditions. The envelope of the Raman OH-stretching vibration band of water is deconvoluted into five Gaussian peaks which can be assigned to five different intermolecular interactions (hydrogen bonding). The intensity of each of the peaks is a function of the temperature and the phase of the water under investigation. The interference of the Raman signals originating from the water vapor is eliminated from the Raman signals originating from the liquid water. Consequently the temperature of the liquid water droplets surrounded by water vapor is accessible which is favorable for the investigation of non-equilibrium sprays where the droplet temperature is different to the vapor temperature.

WATER IN COMETS 71P/CLARK AND C/2004 B1 (LINEAR) WITHSPITZER

We present 5.5 to 7.6 micron spectra of comets 71P/Clark (2006 May 27.56 UT, r_h = 1.57 AU pre-perihelion) and C/2004 B1 (LINEAR) (2005 October 15.22 UT, r_h = 2.21 AU pre-perihelion and 2006 May 16.22 UT, r_h = 2.06 AU post-perihelion) obtained with the Spitzer Space Telescope. The nu_2 vibrational band of water is detected with a signal-to-noise ratio of 11 to 50. Fitting the spectra using a fluorescence model of water emission yields a water rotational temperature of < 18 K for 71P/Clark and approximately less than or equivalent to 14 +/- 2 K (pre-perihelion) and 23 +/- 4 K (post-perihelion) for C/2004 B1 (LINEAR). The water ortho-to-para ratio in C/2004 B1 (LINEAR) is measured to be 2.31 +/- 0.18, which corresponds to a spin temperature of 26^{+3}_{-2} K. Water production rates are derived. The agreement between the water model and the measurements is good, as previously found for Spitzer spectra of C/2003 K4 (LINEAR). The Spitzer spectra of these three comets do not show any evidence for emission from PAHs and carbonate minerals, in contrast to results reported for comets 9P/Tempel~1 and C/1995 O1 (Hale-Bopp).

Alcohol tracer diffusion, density, NMR and FTIR studies of aqueous ethanol and 2,2,2-trifluoroethanol solutions at 25°C

New measurements have been made of the tracer diffusion coefficients of ethanol and 2,2,2-trifluoroethanol (TFE) in aqueous solution at 25°C across the whole composition range. The limiting values at infinite dilution of these alcohols and the series of primary alcohols from methanol to heptanol, the isomeric propanols and butanols and 2-butoxyethanol are found to vary as the alcohol limiting partial molar volume raised to the power -0.56. The self-diffusion coefficient of water lies on the same curve, suggesting that the rate-determining step for diffusion is the same for these alcohols at infinite dilution as it is for water. 1H, 19F and 13C chemical shift and density measurements have been made and apparent molar volumes obtained from the latter. The composition dependence of the ν2 bending vibration band of water in water–TFE at 1640 cm-1 has been examined. The chemical shift and water IR measurements show that water–TFE behaves like other aqueous halogenoethanol solutions with water and hydroxyl proton shifts moving to higher field with increasing alcohol concentration. The results are consistent with thermodynamic data indicating some degree of microheterogeneity in the TFE-rich region of this system and a strengthening of water–TFE H-bonding on dilution of TFE. This is the opposite of what is observed for water–ethanol. We were unable to find any evidence from the diffusion data for the formation of water adducts to ethanol chains at high ethanol concentration in water–ethanol mixtures as has been suggested in the literature.

Infrared investigation of ionic hydration in ion-exchange membranes. Part 2.—Alkaline earth salts of grafted polystyrene sulphonic acid membranes

Infrared spectroscopic studies have been performed on thin ion-exchange membranes which consist of alkaline earth salts of polystyrene sulphonic acid grafted on a Teflon FEP matrix. The membranes were placed at isopiestic equilibrium with water vapour in the sampling cell. The water absorption isotherm at 25 °C has been determined by measuring the integrated absorbance of the sorbed-water bending vibration. In the case of Mg2+, Ca2+ and Sr2+ salts the isotherms exhibit an absorption step with a hysteresis. The frequency of the symmetrical stretching band of the SO–3 group passes through a minimum, and the OH stretching band of water in the membrane passes through a maximum at the relative water vapour pressure corresponding to the step displayed by the absorption isotherm.The dependence of the bending vibration band of water is also analysed in terms of solvent structure in the membrane. A model of hydration of alkaline earth salts of an FEP–PSSA membrane which emerges from the spectral analysis is suggested.

Change in the width of the vibrational bands of water when nonelectrolytes are dissolved in it

Change in the width of the vibrational bands of water when nonelectrolytes are dissolved in it

Effect of perchlorates on the infrared bands of water: III. The structural model

The splitting of OD bands of HDO in the presence of perchlorates is studied and a structural model of solution is proposed. The assignment of D 2O and H 2O stretching bands in perchlorate solutions is discussed and the effect of temperature and of perchlorate on the vibrational bands of water are compared. Two other band-splitting anions are presented and the problem of anion-water hydrogen bonding is analysed.

Changes in phlogopites during their artificial alteration

AbstractWhen phlogopites containing only a little iron are artificially altered with sodium tetraphenylboron solutions, the vermiculite-like products contain fewer interlayer cations than the original micas. Structural formulae of the products are calculated from the chemical analyses, together with infrared examination of the angular vibration band of water at 1650 cm−1 to distinguish between water of hydration and hydroxyl groups. The formulae obtained are consistent with the weight-loss curves and show that the products contain, more than 4(OH,F) per formula unit. The interpretation of these formulae is that the silicate layers lose net negative charge by protonation of structural oxygen anions to form new hydroxyl groups.