A Review of Infrared Spectra from Wood and Wood Components Following Treatment with Liquid Ammonia and Solvated Electrons in Liquid Ammonia

ABSTRACT

The chemical changes that occur in wood and wood components (cellulose, holocellulose and lignin) following treatment with liquid ammonia and solvated electrons (e^? _s,) in liquid ammonia have been investigated using FTIR spectroscopy.

When ammonia penetrates into a wood structure, all carboxylate groups will react with ammonia to form ammonium salts, aldehydic and ketonic groups will follow a similar reaction to produce imines, and ester groups will react to forni amides.

After treatment with (e^? _s) in liquid ammonia, wood samples show diminished absorption around 15 13 cm^?1, a position corresponding to aromatic groups, and diminished absorption peaks associated with aldehydic, ketonic, and ester groups.

The overall changes in the IR spectra of cellulose in liquid ammonia and (e^? _s) in liquid ammonia are not dramatic. The IR spectra of the isolated holocellulose after treatment with (e^? _s) in liquid ammonia have intensities and band shape similar to those of cellulose. The isolated lignin behaves in a manner similar to wood, in that the liquid ammonia causes some decrease in the intensities of absorptions associated with C-O and C=O bands, and increase in strength of the amide functional group at 1600 cm^?1. The resulting extracts of wood, following treatment with (e^? _s) in liquid ammonia, appear to loose their “aromaticity”.

Because wood has long been used, and still is used extensively as an important constructional material, the changes in mechanical characteristics caused by the action of various reducing agents appears to have been an important area of scientific interest. The following review focuses on the chemical changes in the functional groups of the surface moieties of wood when treated with a reducing agent, such as (e^? _s + NH_3liq), using infrared spectroscopy.     

Magnetostriction measurements of CoS2 single crystal

The magnetorestriction constants of CoS₂ single crystal were measured by a capacitance method in a temperature range from liquid N₂ to the Curie temperatures.The constants γ₁₀₀ and γ₁₁₁ are ?1.9 × 10^?6 and 5.7 × 10^?6 at liquid N₂ temperature respectively, and the absolute values of the constants decrease monotonically with the increase of the temperature. The volume magnetorestriction constant δω/δH at 110 K in the ferromagnetic state is 6 × 10^?10 Oe^?1.     

Systematics of EPR spectra of GD3+ in some isostructural rare-earth trisulphate octahydrate hosts

X-band data on Gd³⁺ ions doping some isostructural single crystals of rare-earth trisulphate octahydrate [R₂(SO₄)₃·8H₂O] single crystals (RSH) have been obtained at room temperature for the hosts characterized by R = Pr, Nd, Sm, Eu, Yb and Y, and at liquid nitrogen and liquid helium temperatures for the hosts characterized by R = Pr, Sm, Eu and Y. The data are analyzed using a rigorous least-squares fitting procedure in which all resonant line positions obtained for various orientations of the external magnetic field are fitted simultaneously to the same spin Hamiltonian parameters. The intensities of the lines obtained at liquid helium temperatures indicate the absolute sign of the parameter b₂⁰ to be negative for R = Pr, Eu and Y, whereas for the Sm host the sign of b₂⁰ is found to be positive. While the parameter b₂⁰ does not exhibit a clear cut linear dependence upon the host ion radius, the parameter b₂⁰ is found to behave approximately linearly as a function of the host-ion radius. On the other hand, the zero-field splitting is found to be a linear function of the host ion radius at all three temperatures—room, liquid nitrogen and liquid helium.A comparison is presented of the systematics of the EPR spectra for the RSH hosts with those for some other isostructural rare-earth hosts.     

Elastic constants of galena down to liquid helium temperatures

The elastic constants of single crystal galena have been determined from the measured ultrasonic velocities down to liquid helium temperature. A cryostat incorporating an arrangement to inject the liquid bonding material at low temperature is described. At 5 K, the values of elastic constants are C₁₁=14.9₀, C₁₂=3.5₁ and C₄₄=2.9₂×10¹⁰ N/m².     

Ionic liquid type dye-sensitized solar cells: increases in photovoltaic performances by adding a small amount of water

Increases in photovoltaic performances for dye-sensitized solar cells having ionic liquid type electrolytes are reported. These results are explained by diffusion coefficient for I₃⁻, charge transfer resistances on counter electrodes, flat band potentials of TiO₂, redox potentials for I⁻/I₃⁻, electron diffusion constants, electron life time, and diffusion length in TiO₂ layers. Methylpropylimidazolium iodide is selected because of the lowest viscosity and the highest conductivity. Increases in the photovoltaic performance are observed when a small amount of water was added into the ionic liquid consisting of both LiI and t-butylpyridine as the additives. These improvements are brought about by enhancements of all of J_sc, ff and V_oc. The increases in J_sc and ff are associated with the decrease in charge transfer resistances on counter electrodes and increases in ionic conductivities. V_oc may be explained by an increase in the difference between redox potentials of I⁻/I₃⁻ and Fermi level.     

Electrical conductivity and dynamics of quasi-solidified lithium-ion conducting ionic liquid at oxide particle surfaces

Lithium ion conducting solid-state composites consisting of lithium ion conducting ionic liquid, lithium bis(trifluoromethanesulfonyl)amide (Li-TFSA) dissolved 1-ethyl-3-methyl imidazolium bis(trifluoromethylsulfonyl)amide (EMI-TFSA), denoted by [yMLi⁺][EMI⁺][TFSA⁻] in this study, and various oxide particles such as SiO₂, Al₂O₃, TiO₂ (anatase and rutile) and 3YSZ are synthesized via a liquid route for the molar concentration of lithium, y, to be 1. The composite consists of SiO₂ and the ionic liquid with y = 0.2 was also prepared. The ionic liquid are quasi-solidified at the above oxide particle surfaces when x is below 40 for y = 1 and x is below 30 for y = 0.2, corresponding to the confinable thickness of the ionic liquid at the oxides' surfaces to be approximately 5-10 nm regardless of the oxide compositions. The electrical conductivities of x vol.%[yMLi⁺][EMI⁺][TFSA^-]-SiO₂, Al₂O₃, TiO₂s or 3YSZ composites are evaluated by ac impedance measurements. The quasi-solid-state composites exhibited liquid-like high apparent conductivity, e.g. 10^− 3.3-10^− 2.0 S cm^− 1 in the temperature range of 323-538 K for SiO₂-ionic liquid composites with y = 1. The self-diffusion coefficients of the constituent species of x vol.% [yMLi⁺][EMI⁺][TFSA⁻] (x is below 40, y = 0.2 and 1) − SiO₂ are evaluated by the Pulse Gradient Spin Echo (PGSE)-NMR technique in the temperature range of 298-348 K. By the quasi-solidification of the ionic liquid at SiO₂ particle surfaces, the absolute values of the diffusion coefficients of all constituent species decreased. The SiO₂ surfaces work to promote ionization of ion pair, [EMI⁺][TFSA⁻], while significant influence on the solvation coordination, [Li(TFSA)_n + 1]ⁿ⁻, was not observed. The apparent transport numbers of Li-containing species both in the bulk and the quasi-solidified ionic liquid showed similar values with each other, which was evaluated to be in the range of 0.010-0.017 for y = 0.2 and 0.051-0.093 for y = 1 in the abovementioned temperature range.     

Nuclear Spin Relaxation in Some Non-viscous Media Using the 181Hf Probe

Perturbed angular correlation (PAC) studies have been performed in liquid mercury, HCl media of different acid strengths, H₂O and H₃PO₄ using a ¹⁸¹Hf probe. It is found that, in case of H₂O, interaction between the nucleus and its excited atom following the β⁻ decay of ¹⁸¹Hf is a possible mechanism for the nuclear spin relaxation in this environment. In the liquid mercury and different acid media, however, the perturbations are found to arise due to molecular fluctuations.     

Development of optical methods for simultaneous detection of I2, I−, IO 3 − , and I 3 − in liquid media in real Time

The absorption spectra of IO₃⁻ in liquid media are experimentally studied in the UV spectral range. The absorption cross sections are determined in the range 200–265 nm. The results are used to propose an optical method for the real-time simultaneous detection of molecular iodine and the I⁻, IO₃⁻ and I₃⁻¹ anions in liquid media. The measurement sensitivity for the above substances is sufficient for monitoring of the kinetics of physicochemical reactions that take place at various stages of processing of the spent nuclear fuel. This circumstance makes it possible to increase the efficiency and improve the ecological safety of the process.     

Mobility and lifetime of negative charges in liquid H2

Recent experiments on the mobility ofe ^– in liquid H₂ have shown features that differ drastically from those of liquid He, although the adopted theories for such mobilities are quite similar. The differences are attributed to the existence of a second type of charge carriers (different from bubbles), namely H^–(H₂) _x -clusters. The effective radius and the decay channels of these carriers are investigated theoretically.P.N. Lebedev Physical Institute of the Academy of Sciences of Russian, Leninsky prospect 53, Moscow 117924, Russia     

Atomic reorientation rates in liquid chalcogenide glasses: NMR in Se and As2Se3

Temperature dependence of the NMR spectrum in liquid Se indicates that atomic reorientation in this molten ring-chain structure glass is governed by a distribution of correlation times with a median of τ^∗ = 5 × 10⁻⁵sec at 220°C. In liquid layer structure glasses at equivalent viscosity, atomic reorientation rates are not sufficient to narrow observed NMR spectra. SeSe and AsSe bonds in glassy Se and As₂Se₃ are distinguishable on the basis of their chemically shifted Se⁷⁷ NMR spectra.     

Optical absorption spectrum of diammonium nickel bis(tetrafluoroberyllate) hexahydrate

The optical absorption spectrum of diammonium nickel bis (tetrafluoroberyllate) hexahydrate (NH₄)₂Ni(BeF₄)₂.6H₂O has been investigated at the laboratory and liquid nitrogen temperatures. The spectrum is characteristic of the Ni²⁺ ion in an octahedral crystal field. Splitting of one of the bands at the liquid nitrogen temperature are attributed to the spin-orbit interaction.     

The absorption and magnetic circular dichroism of spectra of Cs2NaPrCl6

The room temperature absorption and magnetic circular dichroism spectra and the absorption spectrum at liquid helium (liquid He) temperature have been measured for Cs₂NaPrCl₆. At room temperature the crystal is cubic and the Pr³⁺ sites have O _h symmetry. All terms above 15 000 cm^-1, except ¹S₀, have been assigned and a previous assignment in PrCl₆ ^3- has been shown to be incorrect. The transition at 20 631 cm^-1 is assigned to ³H₄(A _1g ) →³P₁(T _1g ), in contradiction to previous assignments of Pr³⁺ spectra in other systems. A rich vibrational structure was observed in every transition. Vibrations have been assigned using the site group approximation and there is substantial agreement with the vibrational assignments in Cs₂NaEuCl₆. A crystal phase transition takes place between room temperature and liquid nitrogen temperature and the O _h forbidden transitions, A _1g →E_g and T _2g , are observed. At lower temperatures many additional lines are observed but it is unclear presently whether they are due to lower symmetry or a breakdown of the site group approximation.     

Crystal field effects on the magnetic and hyperfine properties of Yb3+ in ytterbium ethylsulfate

The magnetic and hyperfine properties of Yb³⁺ in Yb(C₂H₅SO₄)₃·.9H₂O have been studied using the crystal field (CF) obtained from an analysis of the observed absorption spectra of the crystal. The principal magnetic susceptibilities are in reasonable agreement with those observed both at liquid oxygen and liquid helium temperatures. The observed reversal of magnetic anisotropy at 17.7K is also corroborated. The Schottky heat capacity shows a peak at around 40K. The magnetic hyperfine field due to the 4f electrons at the nucleus is found to be 1.79MG. The hyperfine heat capacity C_N has a Schottky anomaly at about 25 mK. Above 1K, in the liquid helium range, C_N follows a simple T^?2 law as observed by Cooke et al. It is concluded that in the rare earth ethylsulfates a single suitable CF gives a good account of the various properties from room temperature down to liquid He temperatures.     

Raman Study of the Effect of NaClO4 and NaI on the Hydrogen-Bonded Structure of Liquid NH3

Abstract

Recent studies^1,2 of the Raman spectra of liquid ammonia have been in disagreement with regard to the assignment of bands in the 3000 cm^?1 region. This region is complicated by Fermi resonance between the ν₁ (A₁) fundamental stretching mode and the 2ν₄ (A₁) overtone of the bending mode. In an effort to help clarify these assignments and to study further the structure of liquid ammonia, it was decided to measure the Raman spectrum of several salt solutions in liquid ammonia.     

63Cu and65Cu Fourier transform nuclear magnetic resonance studies

⁶³Cu and⁶⁵Cu NMR studies are reported in liquid and solid copper (I) compounds. Ratios ofg _I-factors, nuclear magnetic moments and nuclear magnetic shielding constants in the atomic reference scale are given for⁶³Cu and⁶⁵Cu in a solution of Cu(I)(CH₃CN)₄BF₄ in CH₃CN, which is a reasonable reference sample due to the relatively narrow NMR line.     

LiF晶体F3+色心的实验研究

本文从实验上系统地研究了在不同条件下电子束辐照LiF晶体所形成的F₃⁺色心的光学特点。并且由荧光光谱分析了F₃⁺心和F₂心,的相对密度关系。实验表明,辐照温度对于色心的形成和密度的相对大小起着关键的作用。主要实验结果包括:1)在液氮温度下辐照,然后在暗处加热至室温可形成高密度的F₃⁺心,表现在发射光谱中F₃⁺心荧光占绝对优势。吸收光谱表明没有N心和R心。2)由动力学荧光谱可以看到低温辐照的样品在F₂⁺心衰变的同时,F₃⁺心密度迅速增加。而室温辐照的样品则是F₂心,与F₃⁺心的密度以近似相等的速率增加。3)详细观察了F₃⁺心530nm荧光激发带与F₂心670nm荧光激发带半宽度的变化和双峰结构。由此对M吸收区的发光特点作了解释。 关键词：     

Structure and dynamics of the He 2 * (a 3Σ u + molecular complex in condensed phases of helium

An investigation is made of the absorption spectra of triplet metastable helium molecules in the a ³Σ _u ⁺ state in liquid ⁴He and ³He at various pressures and in dense ³He gas. An analysis of the spectrum corresponding to the a ³Σ _u ⁺ → c ³Σ _g ⁺ transition confirms the conclusion that there is a microscopic bubble surrounding the molecule in liquid helium. A simple approximation is proposed for the wave function of the valence electron of the molecule and the parameters of the bubble are determined for various experimental conditions. The coefficient of molecular recombination in liquid ³He and ⁴He was determined experimentally at various pressures and in dense cold ³He gas. The results show good agreement with the theory of mutual recombination limited by molecular diffusion under conditions of strong van der Waals interaction. It is shown that in the condensed phases of helium the polarization of the molecules under the action of the magnetic field does not lead to suppression of their mutual recombination, and this is confirmed experimentally.     

The properties of liquid nitrogen

Measurements are reported of the nitrogen-nucleus spin-lattice relaxation time, T ₁, in liquid nitrogen ¹⁴N₂ and liquid nitrogen ¹⁵N₂ along the liquid-vapour coexistence line from 77·3 K up to the critical temperature and for the fluid at the critical density up to 145 K. Values of the molecular reorientational correlation time, τ _Q , and the molecular angular momentum correlation time, τ _sr , are determined. The values of τ _Q and τ _sr and the relation between them are discussed in terms of various theories of molecular reorientation in molecular liquids. The values of τ _Q and τ _sr are also compared with those predicted by computer simulation methods. It is concluded that the molecular reorientation in liquid nitrogen is not by classical reorientational diffusion except possibly at temperatures near the triple point. It is suggested that at higher temperatures the reorientation is on average by rather large angles and that the process may be quantum mechanical to some extent. (For paper I in this series see reference [8].)     

An IR spectroscopic study of liquid ozone and ozone dissolved in liquid argon

We have measured and interpreted the IR spectra of liquid ozone films at 78–85 K and ozone dissolved in liquid argon at 91–95 K. A less hindered rotation of ozone molecules in argon manifests itself as an intensity redistribution, caused by the Coriolis interaction, from the states ν₃(B ₁) and ν₁ + ν₃(B ₁) to the states ν₁(A ₁) and 2ν₁(A ₁), respectively. The occurrence of wings in the contours of the bands ν₁(A ₁), 2ν₁(A ₁), and 2ν₃(A ₁) in liquid Ar and their absence in the spectrum of O₃ also confirms the conclusion that the rotational motion of ozone molecules in an inert solvent at low temperatures is relatively less hindered. Maxima of ozone bands in Ar solution are shifted toward lower frequencies compared to those in the gas phase by 1–30 cm^?1, which corresponds to the following shifts of harmonic frequencies of the molecule: Δω₁ = ?1.85(5) cm^?1, Δω₂ = ?0.67(7) cm^?1, Δω₃=?7.20(5) cm^?1. It was found that the absorption band of the ν₃ mode in the spectrum of O₃ in the liquid phase has a complicated asymmetric contour because of the resonance dipole-dipole interaction. The first and second spectral moments of this band have been determined to be M ₁ = 1030.6 cm^?1 and M ² = 240.0 cm^?2.     

N.M.R. study of the 125Te shielding anisotropy of tellurophene dissolved in various nematic liquid crystals

The ¹²⁵Te N.M.R. spectrum of tellurophene in three liquid crystals was recorded and analysed. The different orientational behaviour of tellurophene in the liquid crystals enabled the anisotropy of the tellurium-125 shielding tensor, σ _zz - 1/2(σ _xx + σ _yy ), and the difference σ _xx - σ _yy of the tensor elements to be determined. The resulting values are -1569 ± 21 ppm and 307 ± 26 ppm, respectively. The analysis of the ¹²⁵Te N.M.R. spectra is also discussed.