Spectroscopic Data Systems Infrared

Specinfo, from Chemical Concepts, is a factual database information system for spectroscopic data with more than 660000 digital spectra of 150000 associated structures [24], The database covers nuclear magnetic resonance spectra ( H-, C-, N-, O-, F-, P-NMR), infrared spectra (IR), and mass spectra (MS). In addition, experimental conditions (instrument, solvent, temperature), coupling constants, relaxation time, and bibliographic data are included. The data is cross-linked to CAS Registry, Beilstein, and NUMERIGUIDE. 

Although the majority of the lipids in M. laidlawii membranes appear to be in a liquid-crystalline state, the system possesses the same physical properties that many other membranes possess. The ORD is that of a red-shifted a-helix high resolution NMR does not show obvious absorption by hydrocarbon protons, and infrared spectroscopy shows no ft structure. Like erythrocyte ghosts, treatment with pronase leaves an enzyme-resistant core containing about 20% of the protein of the intact membrane (56). This residual core retains the membrane lipid and appears membranous in the electron microscope (56). Like many others, M. laidlawii membranes are solubilized by detergents and can be reconstituted by removal of detergent. Apparently all of these properties can be consistent with a structure in which the lipids are predominantly in the bilayer conformation. The spectroscopic data are therefore insufficient to reject the concept of a phospholipid bilayer structure or to... 

There are few papers devoted to the detailed analysis of infrared spectra of six-membered sulfur containing ring systems. The majority of infrared spectroscopic data feature in the experimental section of papers concerned with either synthesis or reactivity of the ring system, and in these papers usually only IR bands associated with multiple bond (C=C, C=S, SO, and SO2) stretching modes are assigned. 

At the beginning, the electric double layer at the solid-aqueous electrolyte solution interface was characterized by the measurements of the electrokinetic potential and stability of dispersed systems. Later, the investigations were supported by potentiometric titration of the suspension, adsorption and calorimetric measurements [2]. Now, much valuable information on the mechanism of the ion adsorption can be obtained by advanced spectroscopic methods (especially infrared ATR and diffuse spectroscopy) [3], Mosbauer spectroscopy [4] and X-ray spectroscopy [5]. Some data concerning the interface potential were obtained with MOSFET [6], and AFM [7]. An enthalpy of the reaction of the metal oxide-solution systems can be obtained by... 

There are no literature reports of structurally characterized SnF4 D2 systems, and only one of a cw-bidentate ligand, i.e. SnF4(2,2 -bipyridyl) . Some reports described SnF4(MeCN)2 as trans-adduct based on infrared and Mossbauer spectroscopic data . Table 76 and 77 provide prominent structurally characterized examples of cis- and trans-SnX4D2 systems. 

Spectroscopic techniques (particularly infrared, x-ray photoelectron, and x-ray absorption spectroscopy) have been applied to fill the information gap about chemical speciation and interfacial reactions of As in model and natural materials. They have been used to determine the stmcture of x-ray amorphous particles involved in interfacial reactions, to identify the types of sorption reactions occurring in simplified model systems containing As and one or more phases, and to identify the valence and speciation of predominant As species present in natural, heterogeneous materials. This chapter summarizes much of the recent spectroscopic information on arsenic speciation in minerals and other solid phases that are analogous to phases present in aquifer sediments. These data are primarily derived from analysis of synthetic samples or natural model compounds. 

A dynamic method for acquiring and treating infrared spectroscopic data from the imidization of a number of polyimide systems is presented. In situ FT-IR analysis of polymer reactions is preferred when doing comparitive studies on a number of polymer systems. For systems where these reactions occur at relatively high temperatures, it is often difficult to obtain good isothermal data for determining kinetic parameters. Kinetic data for several polyimide systems are shown and compared. 

The prospects for actinide lasers, based on available spectroscopic data, is definitely more limited. Although there are a few prospects for visible lasers, the presence of low-lying 6d and electron transfer states can cause intense excited-state absorption, thus limiting oscillation principally to the infrared. Strong ion-host interactions increase the probabilities for radiative and nonradiative transitions and must be carefully considered with respect to the overall operation and efficiency of any practical system. 

Extensive spectroscopic data on substituted 1,3-benzoxazepines have been reported by Desbene and Cherton <84T3567>, while H NMR and infrared absorption data on the parent isomeric system. 

Most of the applications with infrared spectroscopic data involve classification, calibration, and prediction. This is because the infrared profiles describe chemical structure that is directly related to the physical and/or chemical properties of the systems analyzed. Changes in the infrared profile of a system imply variation in the chemical structure and hence variations in the properties of the system. These data profiles contain information, and extraction of this information requires multivariate data analysis. 

Electron injection dynamics in the conduction band of metal oxide materials from dye molecules or metal nanoparticles, which is important when applied to sensitized solar cells, can be monitored in the infrared by 100 fs time resolution. In this chapter, technical details of femtosecond visible-pump/IR-probe transient absorption spectroscopy and some typical spectroscopic data revealing the mechanism of electron injection process were described. A great advantage of this technique is that one can observe transient absorption of injected electrons easily because of the intense intraband transition of an electron at the bottom of or at the trap level just below the conduction band of the metal oxide that forms an electrode. In the case of dye-sensitized solar cells, the effects of metal oxide, dye, solvent and additive ions on the rate and efficiency of electron injection were discussed in detail. One recent discovery, plasmon-induced electron injection from a gold nanoparticle to a Ti02 nanoparticle, was presented to show how femtosecond visible-pump/IR-probe transient absorption spectroscopy is useful in studying this kind of new charge transfer dynamics in a nano-structured system. 

Obviously, a great deal more information could be obtained if the isomeric ions could be probed spectroscopically. Vibrational states of the various isomers are not generally well known, but some structural information is available. Thus, the rotational structure of vibrational transitions may provide a better signature for particular isomers. Certainly, insufficient data are available about the potential surfaces of electronically excited states for electronic excitation to be used as a probe, e.g., as in the very sensitive laser induced fluorescence. At present, there are sensitivity limitations in the infrared region of the spectrum, but this may well be an avenue for the future. The study of isomeric systems and their potential surfaces has just begun ... 

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