Observation of Solid–Liquid Phase Transitions of Brine Using the Far-Ultraviolet Charge-Transfer-to-Solvent Band

Although determining the chemical states of salts and ions is critical in numerous fields, such as elucidating biological functions and maintaining food quality, the current direct observation methods are insufficient. We propose a spectral analysis method of directly observing the phase transitions of NaCl solutions using the changes in the charge-transfer-to-solvent band and the absorption band representing the first electron transition (Ã ← X̃) of H2O. The intensities of these bands may be observed using attenuated total reflection far-ultraviolet spectroscopy. According to the well-known phase diagram of aqueous NaCl, we observe spectral changes during freezing–thawing and may spectroscopically detect the phase transitions from liquid to mixed liquid–solid and solid phases, including eutectic crystals, in addition to their coexistence curves

Observation of Solid–Liquid Phase Transitions of Brine Using the Far-Ultraviolet Charge-Transfer-to-Solvent Band

Although determining the chemical states of salts and ions is critical in numerous fields, such as elucidating biological functions and maintaining food quality, the current direct observation methods are insufficient. We propose a spectral analysis method of directly observing the phase transitions of NaCl solutions using the changes in the charge-transfer-to-solvent band and the absorption band representing the first electron transition (Ã ← X̃) of H2O. The intensities of these bands may be observed using attenuated total reflection far-ultraviolet spectroscopy. According to the well-known phase diagram of aqueous NaCl, we observe spectral changes during freezing–thawing and may spectroscopically detect the phase transitions from liquid to mixed liquid–solid and solid phases, including eutectic crystals, in addition to their coexistence curves

Observation of Solid–Liquid Phase Transitions of Brine Using the Far-Ultraviolet Charge-Transfer-to-Solvent Band

Although determining the chemical states of salts and ions is critical in numerous fields, such as elucidating biological functions and maintaining food quality, the current direct observation methods are insufficient. We propose a spectral analysis method of directly observing the phase transitions of NaCl solutions using the changes in the charge-transfer-to-solvent band and the absorption band representing the first electron transition (Ã ← X̃) of H2O. The intensities of these bands may be observed using attenuated total reflection far-ultraviolet spectroscopy. According to the well-known phase diagram of aqueous NaCl, we observe spectral changes during freezing–thawing and may spectroscopically detect the phase transitions from liquid to mixed liquid–solid and solid phases, including eutectic crystals, in addition to their coexistence curves

Observation of Solid–Liquid Phase Transitions of Brine Using the Far-Ultraviolet Charge-Transfer-to-Solvent Band

Although determining the chemical states of salts and ions is critical in numerous fields, such as elucidating biological functions and maintaining food quality, the current direct observation methods are insufficient. We propose a spectral analysis method of directly observing the phase transitions of NaCl solutions using the changes in the charge-transfer-to-solvent band and the absorption band representing the first electron transition (Ã ← X̃) of H2O. The intensities of these bands may be observed using attenuated total reflection far-ultraviolet spectroscopy. According to the well-known phase diagram of aqueous NaCl, we observe spectral changes during freezing–thawing and may spectroscopically detect the phase transitions from liquid to mixed liquid–solid and solid phases, including eutectic crystals, in addition to their coexistence curves

Observation of Solid–Liquid Phase Transitions of Brine Using the Far-Ultraviolet Charge-Transfer-to-Solvent Band

Although determining the chemical states of salts and ions is critical in numerous fields, such as elucidating biological functions and maintaining food quality, the current direct observation methods are insufficient. We propose a spectral analysis method of directly observing the phase transitions of NaCl solutions using the changes in the charge-transfer-to-solvent band and the absorption band representing the first electron transition (Ã ← X̃) of H2O. The intensities of these bands may be observed using attenuated total reflection far-ultraviolet spectroscopy. According to the well-known phase diagram of aqueous NaCl, we observe spectral changes during freezing–thawing and may spectroscopically detect the phase transitions from liquid to mixed liquid–solid and solid phases, including eutectic crystals, in addition to their coexistence curves

Observation of Solid–Liquid Phase Transitions of Brine Using the Far-Ultraviolet Charge-Transfer-to-Solvent Band

Although determining the chemical states of salts and ions is critical in numerous fields, such as elucidating biological functions and maintaining food quality, the current direct observation methods are insufficient. We propose a spectral analysis method of directly observing the phase transitions of NaCl solutions using the changes in the charge-transfer-to-solvent band and the absorption band representing the first electron transition (Ã ← X̃) of H2O. The intensities of these bands may be observed using attenuated total reflection far-ultraviolet spectroscopy. According to the well-known phase diagram of aqueous NaCl, we observe spectral changes during freezing–thawing and may spectroscopically detect the phase transitions from liquid to mixed liquid–solid and solid phases, including eutectic crystals, in addition to their coexistence curves

Far-Ultraviolet Spectroscopy and Quantum Chemical Calculation Studies of the Conformational Dependence on the Electronic Structure and Transitions of Cyclohexane, Methyl and Dimethyl Cyclohexane, and Decalin; Effects of Axial Substitutions on the Electronic Transitions

Far-ultraviolet (FUV) spectra were measured for cyclohexane, methyl cyclohexane, six isomers of dimethyl cyclohexane, and cis- and trans-decalin. Attenuated total reflection-FUV (ATR-FUV) spectroscopy, which we originally proposed, provides systematic information about the excitation states of saturated organic molecules and the hyperconjugation of σ bonds. The FUV spectra of cyclohexane and methyl cyclohexane in neat liquids showed a band with central wavelengths near 155 and 162 nm. The simulation spectrum of cyclohexane calculated by time-dependent density-functional theory (TD-DFT) (CAM-B3LYP/aug-cc-pVTZ) gives two bands at 146 and 152 nm owing to the transition from HOMO-2 to Rydberg 3pz (Tb) and those from HOMO and HOMO-1 to Rydberg 3px/3py (Ta), respectively. The simulation spectrum of methyl cyclohexane with the equatorial substituent has peaks at approximately the same positions as cyclohexane. The calculated molar absorption coefficient is larger than that of cyclohexane, estimating the observed FUV spectra very well. The FUV spectra of dimethyl cyclohexane with two methyl substituents at the equatorial positions (trans-1,2-, cis-1,3-, and trans-1,4-) and trans-decalin had similar features to those of cyclohexane and methylcyclohexane. The TD-DFT calculations revealed that the shoulders at the shorter- and longer-wavelength sides of the band center of dimethyl cyclohexane (with methyl substituents at equatorial positions) and trans-decalin are assigned to Tb and Ta, respectively. In the case of dimethyl cyclohexane with one methyl substituent in the axial position (cis-1,2-, trans-1,3-, and cis-1,4-) and cis-decalin, the band caused by Tb decreased compared to those of the other compounds. The decrease in intensity and the longer-wavelength shift of the Tb band for dimethyl cyclohexane (with one methyl group at the axial position) and cis-decalin revealed that the band on the longer-wavelength side was assigned to the overlap band of Ta and Tb. The reason for such a large spectral alternation for the axial substitution may be the increase in the orbital energy of HOMO-2, which has its electron density concentrated at the axial C–H bond. Regarding the effect of the hyperconjugation of C–C and C–H σ orbitals, the second perturbation energies of the interaction between Cα–Hax and Cβ–Hax were estimated for molecules by natural bond orbital (NBO) analysis. There is a correlation between the orbital energies of HOMO-2 and the changes in vicinal interaction by axial substitution

Changes in the Electronic Transitions of Polyethylene Glycol upon the Formation of a Coordinate Bond with Li⁺, Studied by ATR Far-Ultraviolet Spectroscopy

This study investigates the electronic transitions of complexes of lithium with polyethylene glycol (PEG) by the absorption bands of solvent molecules via attenuated total reflectance spectroscopy in the far-UV region (ATR–FUV). Alkali-metal complexes are interesting materials because of their functional characteristics such as good ionic conductivity. These complexes are used as polymer electrolytes for Li batteries and as one of the new types of room-temperature ionic liquids, termed solvation ionic liquids. Considering these applications, alkali-metal complexes have been studied mainly for their electrochemical characteristics; there is no fundamental study providing a clear understanding of electronic states in terms of electronic structures for the ground and excitation states near the highest occupied molecular orbital–lowest occupied molecular orbital transitions. This study explores the electronic transitions of ligand molecules in alkali-metal complexes. In the ATR–FUV spectra of the Li–PEG complex, a decrease in intensity and a large blue shift (over 4 nm) were observed to result from an increase in the concentration of Li salts. This observation suggests the formation of a complex, with coordinate bonding between Li+ and the O atoms in PEG. Comparison of the experimental spectrum with a simulated spectrum of the Li–PEG complex calculated by time-dependent density functional theory indicated that changes in the intensities and peak positions of bands at approximately 155 and 177 nm (pure PEG shows bands at 155, 163, and 177 nm) are due to the formation of coordinate bonding between Li+ and the O atoms in the ether molecule. The intensity of the 177 nm band depends on the number of residual free O atoms in the ether, and the peak wavelength at approximately 177 nm changes with the expansion of the electron clouds of PEG. We assign a band in the 145–155 nm region to the alkali-metal complex because we observed a new band at approximately 150 nm in the ATR–FUV spectra of very highly concentrated binary mixtures

sj-pdf-1-asp-10.1177_00037028221086913 – Supplemental Material for A Study of C=O…HO and OH…OH (Dimer, Trimer, and Oligomer) Hydrogen Bonding in a Poly(4-vinylphenol) 30%/Poly(methyl methacrylate) 70% Blend and its Thermal Behavior Using Near-Infrared Spectroscopy and Infrared Spectroscopy

Supplemental Material, sj-pdf-1-asp-10.1177_00037028221086913 for A Study of C=O…HO and OH…OH (Dimer, Trimer, and Oligomer) Hydrogen Bonding in a Poly(4-vinylphenol) 30%/Poly(methyl methacrylate) 70% Blend and its Thermal Behavior Using Near-Infrared Spectroscopy and Infrared Spectroscopy by Harumi Sato, Yusuke Morisawa, Satoshi Takaya and Yukihiro Ozaki in Applied Spectroscopy</p

Electronic Transitions of Protonated and Deprotonated Amino Acids in Aqueous Solution in the Region 145–300 nm Studied by Attenuated Total Reflection Far-Ultraviolet Spectroscopy

The electronic transitions of 20 naturally occurring amino acids in aqueous solution were studied with attenuated total reflection far-ultraviolet (ATR-FUV) spectroscopy in the region from 145 to 300 nm. From the measured ATR spectra of sample solutions, the FUV absorption spectra attributed to the amino acids were separated from the intense solvent absorption by using a modified Kramers–Kronig transformation method. The FUV absorption spectra of the amino acids reflect the protonation states of the backbone and side-chain structures. The contributions of the side chains to the spectra were also examined from the difference spectra subtracting the corresponding Gly spectrum from each spectrum. The observed spectra were compared mostly with the electronic transition studies of the molecular fragments of the amino acids in gas phase. The FUV spectra of the amino acids exhibited the intra- and intermolecular electronic interactions of the solute–solute as well as the solute–solvent, and those are essential factors to elucidate UV photochemical processes of the amino acids in aqueous solution