Liquids spectroscopic properties

According to the complexity of the phenomenon of solvation, experimental results which might have bearings for its understanding are spread throughout the literature. Gas-phase investigations of intermolecular interactions are of a basic interest 23 ) and a large amount work has been done on the thermodynamics and spectroscopic properties of liquid mixtures 29,237-239)... 

When a solute particle is introduced into a liquid, it interacts with the solvent particles in its environment. The totality of these interactions is called the solvation of the solute in the particular solvent. When the solvent happens to be water, the term used is hydration. The solvation process has certain consequences pertaining to the energy, the volume, the fluidity, the electrical conductivity, and the spectroscopic properties of the solute-solvent system. The apparent molar properties of the solute ascribe to the solute itself the entire change in the properties of the system that occur when 1 mol of solute is added to an infinite amount of solution of specified composition. The solvent is treated in the calculation of the apparent molar quantities of the solute as if it had the properties of the pure solvent, present at its nominal amount in the solution. The magnirndes of quantities, such as the apparent molar volume or heat content, do convey some information on the system. However, it must be realized that both the solute and the solvent are affected by the solvation process, and more useful information is gained when the changes occurring in both are taken into account. 

Virtually all of the methods for determining enantiomeric purity rely on the differences in chemical, physical, or spectroscopic properties of dia-stereomers derived from enantiomeric mixtures. We will mention here two of the most straightforward methods, based on gas-liquid chromatography and nuclear magnetic resonance. 

The spectroscopic properties of atoms change when embedded inside a liquid helium matrix. The common features with respect to plasma... 

The extension of continuum models to complex environments is further analyzed by Ferrarini and Corni Frediani, respectively. In the first contribution the use of PCM models in anisotropic dielectric media such as liquid crystals is presented in relation to the calculation of response properties and spectroscopies. In the second contribution, PCM formulations to account for gas-liquid or liquid-liquid interfaces, as well for the presence of a meso- or nano-scopic metal body, are presented. In the case of molecular systems close to metal bodies, particular attention is devoted to the description of the surface enhanced effects on their spectroscopic properties. 

When the phase boundary of a liquid is given by a metal, other phenomena occur. We have so far examined the case of specimens with the metal in a nanoparticle aggregation, with the opportune morphology of the metal subsystem (noble metals are more appropriate) Surface enhancement effects on the spectroscopic property of a chromophore have been evidenced, in agreement with the available experimental findings (especially for SERS, but also for other spectroscopic signals) [9]. In some experiments of this type, the metal is covered by a substance with a dielectric response differing from that of the bulk liquid, Which has also been introduced in PCM [9],... 

The Physicochemical Properties of Solvents and Their Relevance to Electrochemistry. The solvent properties of electrochemical importance include the following protic character (acid-base properties), anodic and cathodic voltage limits (related to redox properties and protic character), mutual solubility of the solute and solvent, and physicochemical properties of the solvent (dielectric constant and polarity, donor or solvating properties, liquid range, viscosity, and spectroscopic properties). Practical factors also enter into the choice and include the availability and cost of the solvent, ease of purification, toxicity, and general ease of handling. 

A mixture of molybdenum hexacarbonyl and 4-chlorophenol is effective in performing al-kyne metathesis of dipropynylated dialkylbenzenes. Alkyne metathesis of these precursors leads to the clean formation of dialkyl poly( paraphenyleneethynylene)s (PPEs) in high yield and with high molecular weights. This facile yet effective access to the PPEs has allowed study of their spectroscopic, structural, and thermal properties. While PPEs have been made before, the dialkyl-PPEs turned out to have particularly interesting optical and liquid-crystalline properties that can be explained in terms of the conformation of the main chains. The PPEs have also been utilized to construct light-emitting diodes and other semiconductor devices. This chapter discusses the interplay of structure, chromicity, and electronic properties of the dialkyl-PPEs. 

The interesting and unusual spectroscopic properties of acylsilanes have received considerable attention.6a,b Unfortunately, a similar systematic study for thioacylsilanes has not been done because of their low thermal stability. These compounds are blue materials [ -max(CCl4) = 678 nm for lb, 692 nm for la,13 and 612 nm for lg16], and are generally liquids except thiobenzoyl-triphenylsilane la, 2,4,6-trimethyl-thiobenzoyltrimethylsilane Is, and 3,5-di-terf-butylthiobenzoyltriphenylsilane le which are solids. 

Concurrently with the view that reactions of electrons and positive ions play an important part in the radiation chemistry of liquids, it was being demonstrated, notably by Hamill(56) and his co-workers over the period 1962-1966, that charge trapping, migration and reaction were also important In the radiation chemistry of many solid systems, especially at low temperatures. As a result of these studies, >-irradiation of low temperature solids has become perhaps the most versatile method of studying the spectroscopic properties of radical anions and cations. 

As already mentioned, several investigators have pointed out that naphthalene or tetrahydrofuran may be incorporated into the coal product (9, 10, 11), In this work we found that chromatographic procedures could be used to separate unbound naphthalene and its reductive alkylation products from the coal alkylation products. The spectroscopic work indicates that the principal resonances of naphthalene and tetrahydrofuran are absent from the butylated coals. Moreover, the mass balance shows that no important quantity of naphthalene or tetrahydrofuran could be incorporated. We supplemented this negative evidence by a comparison of the reaction products obtained from the same coal in a reaction in liquid ammonia. In the most pertinent case the Illinois No. 6 coal was treated with potassium in liquid ammonia. The polyanion was alkylated with butyl iodide. The product distribution obtained by GPC and the spectroscopic properties of these fractions were very closely related to the properties of the reaction products obtained in the reaction with naphthalene in tetrahydrofuran. Recently Larsen and his group found that neither " C-labeled naphthalene nor tetrahydrofuran was incorporated in chemically significant amounts in the coal products separated from the reaction mixture by chromatography (12). 

The "liquid state" in-situ NMR studies made here probe the reactions of physisorbed, and possibly in part chemisorbed, species. NMR studies of olefins adsorbed on acidic catalysts have difficulty evidencing the olefinic nature of the initial chemisorbed species [2,6,7]. This is probably because they are short-lived (e g. carbenium ions) or have poor spectroscopic properties (e g. broad lines). These problems are not resolved by magic angle spinning and solid state methods. 

A new empirical potential for water has been developed using spectroscopic data, which is able to model condensed water with good accuracy.483 The potential is referred to as the VRT(ASP-W)III potential (the third fitting of the Anisotropic Site Potential with Woemer dispersion to Vibration-Rotation Tunnelling data). It give excellent results for vibrational properties of water clusters up to (H20)6, but unlike earlier spectroscopically derived potentials also models the liquid state well. MC simulations are used to study the liquid state properties. It is noted that this potential only partly accounts for many-body interactions (the induction term) and the simulations do not include... 

K. Rurack, K. Hoffmann, W. Al-Soufi, and U. Resch-Genger, 2,2 -Bipyridyl-3,3 -diol Incorporated into AlP04-5 Crystals and its Spectroscopic Properties as Related to Aqueous Liquid Media. J. Phys. Chem. B, 2002, 106, 9744-9752. 

Continuum resonance-Raman scattering can be observed under discrete resonance-Raman scattering conditions only if the resonance fluorescence is quenched, either with an inert gas, or (in the case of condensed phase studies) by the solvent or matrix. Thus, on excitation of a liquid, solution, or solid within the contour of an absorption band, the Raman spectrum observed has the characteristics of the continuum rather than the discrete case or, in other terminology, of resonance Raman, rather than resonance fluorescence spectra. Such spectra provide unique information on the spectroscopic properties of radical cations and ions, some of which species are unstable in air. Particularly noteworthy have been the studies by Andrews et al. (65) which have... 

Van Deun et al. were the first to observe near-infrared luminescence from lanthanide-doped liquid crystal mixtures They studied the spectroscopic properties of the lanthanide(III) / -diketonate complexes [L (dbm)3(phen)], where Ln = neodymium, erbium, ytterbium, and dbm is dibenzoylmethane, in the liquid crystal MBBA. By incorporation of an erbium(III)-doped nematic liquid crystal (ErCls dissolved in E7) in the pores of microporous silicon, narrowing of the erbium(III) emission band in the near-infrared was observedJ Luminescent optically active liquid crystals were obtained by doping [Eu(tta)3-3H20] into a mixture of cho-lesteryl nonanoate, cholesteryl tetradecanoate and the ternary liquid crystal mixture ZLI1083 from MerckJ ... 

The spectroscopic properties of lanthanides in liquids are characterized by broad absorption and emission bands with line-widths that approach those in glasses. Lanthanide fluorescence in liquids is less prevalent than in solids because high frequency vibrations associated with the solvent cause non-radiative relaxation of excited electronic states. In chelates, the lanthanide ion is complexed to several organic groups or ligands. Chelates are soluble in many organic solvents. 

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