Ratiometric detection of Raman hydration shell spectra

Abstract

The micro-structure of hydration shell of solute in water is significant for understanding the properties of aqueous solutions. However the spectra of hydration shell are difficult to be obtained. Herein, a novel Raman ratio spectra, which is obtained through dividing the Raman spectra of aqueous solutions from the spectrum of water, was applied to deduce the spectra of hydration shell of organic (acetone-D6) and inorganic compounds (NaNO 3 , NaSCN, NaClO 4 , Na 2 SO 4 , NaCl) in water. Those spectra of the hydration shell were employed to study the micro-structures of the first hydration shells of anions, the number of water molecules in the first hydration shell of free anions and acetone-D6, and the aggregation behavior of ions in the concentrated aqueous NaNO 3 . The number of water molecules in the hydration shell was supported by our molecular dynamic simulations. The Raman ratio spectra can be widely employed to obtain the spectra of the first hydration shell, and it is helpful to understand the micro-structure of aqueous solutions.

Contacted Ion Pairs in Aqueous CuCl2 by the Combination of Ratio Spectra, Difference Spectra, Second Order Difference Spectra in the UV-Visible Spectra

“…Except the band at 271 nm, the positions of these bands agree well with the positions listed in Table I. Previously, the ratio Raman spectrum and the difference Raman spectrum were successfully used to extract the small spectral band of the hydration shell in aqueous solutions [31]. Here, the simulation demonstrates the ratio spectra and the difference spectra can also be employed to extract the small bands in the UV-Vis spectra.…”

“…Taking Raman spectra as an example, multivariate curve resolution method [32,33], factor analysis [34,35], fitting analysis [36] were used to extract the spectral components in the overlapping spectra. Recently, a new method called Raman ratio spectrum was proposed, and it was successfully employed to extract small Raman bands which were overlapped seriously with a strong band [29][30][31]. The ratio spectrum is obtained by dividing one spectrum by another spectrum at different conditions.…”

“…The spectral overlapping is also obvious in other spectra, such as the Raman spectra. Recently, a novel method called ratio spectra was employed to successfully extract the small components in the overlapping Raman spectra [29][30][31]. For instance, using the Raman Ratio spectrum, the small free OH vibration band was distinguished from the spectrum of water [29], the small amide A band (N-H stretching band) of protein was directly extracted from the spectrum of water [30], the small Raman bands of the hydration shell of ions and organic compound were extracted [31].…”

Intermolecular Interactions in Self-Assembly Process of Sodium Dodecyl Sulfate by Vertically Polarized Raman Spectra

“…The spontaneous Raman setup was described in our previous studies [31][32][33][34][35][36][37], and described briefly here. In this experiment, a cw laser (Coherent, Verdi V5, 532 nm) with 4.0 W power was used as the excitation light.…”

Recent advances in linear and non‐linear Raman spectroscopy. Part XI

“…Wang and co‐workers reported the ratiometric detection of Raman hydration shell spectra. They used a novel Raman ratio spectrum, which was obtained by dividing the Raman spectrum of aqueous solution by the spectrum of water, and used it to deduce the spectra of hydration the shells of organic (acetone‐D6) and inorganic compounds (NaNO3, NaSCN, NaClO4, Na2SO4, NaCl) in water …”