Frequency vibrational spectroscopy

Bain C D 1995 Sum-frequency vibrational spectroscopy of the solid-liquid interface J. Chem. See. Faraday Trans. 91 1281-96... 

Dederichs, F., Friedrich, K F. and Daum, W. (2000) Sum-frequency vibrational spectroscopy of CO adsorption on Pt(l 11) and Pt(llO) electrode surfaces in perchloric acid solution effects of thin-layer electrolytes in spectro-electrochemistry. J. Phys. Chem. B, 104, 6626-6632. 

Liu J, Conboy JC. Direct measurement of the transbilayer movement of phospholipids by sum-frequency vibrational spectroscopy. J. Am. Chem. Soc. 2004 126 8376-8377. 

Phase transitions of pyrazine have been studied by calorimetry. X-ray diffraction, and low-frequency vibrational spectroscopy (597a). 

J.C. Conboy, Investigation of Immiscible Liquid/Liquid Interfaces with Second Harmonic Generation and Sum-Frequency Vibrational Spectroscopy, University of Oregon, Eugene, 1996. 

Beyond neat liquid water sum-frequency vibrational spectroscopy allowed the study of the alkyl chain conformation of surfactants such as dodecyl sulfate described in Ch. 9, that mediates the interfaces between water and CCI4 when the head group or the cations of these amphiphile molecules varied (77, 78). It also gave experimental evidence that the water surface favours the presence of anions rather than cations (79). This effect is at the origin of the oxidative power of sea water, which is ascribed to Cl anions positioned on surfaces of liquid-water droplets. It has also been applied to other H-bonded liquid water, such as methanol, where it could be demonstrated that the CH3 groups point away from the liquid at the interface with vapour (73). This is also the case for CH3 groups of acetic acid (80). Also the surface of liquid water could be shown (81) to be disrupted by even such a small amount as 0.3% of acetic acid, which does not ionize, even at this low... 

We thus see that, as for the time-resolved nonlinear IR methods, sum-frequency vibrational spectroscopy is a valuable tool to convey information on H-bonds, particularly H-bonds at interfaces. 

Figure 9.3 clearly shows that solvation of an anion is different from that of a cation an anion accepts H-bonds from H2O molecules, whereas a cation attracts the lone-pair electrons of H2O molecules, thus having the same structural effect as an H-bond donor. This dissymmetry of solvation makes anions and cations behave differently at water surfaces or interfaces, a result that has been experimentally put into evidence by sum-frequency vibrational spectroscopy (38), a surface-specific method described in Ch. 4. Cations thus display tendencies to stay in the bulk, because on arriving at the surface, some of the four H2O molecules bound to them cannot establish H-bonds when arriving on the surface. This is not so for anions, as the H2O bound to them already establish H-bonds on them. The surface therefore favours the presence of anions. This effect is at the origin of the oxidative power of sea water, which is ascribed to Cl anions positioned on surfaces of liquid water droplets. 

LOW FREQUENCY VIBRATIONAL SPECTROSCOPY OF MOLECULAR COMPLEXES, Erich Knozinger and Otto Schrems... 

Planar supported lipid membranes were first prepared and studied as simplified structural models of cell membranes [4,6, 32], and more recently as biocompatible coatings for sensor transducers and other synthetic materials [33-37], A major advantage of the planar geometry relative to vesicles, and a major contributor to the expansion of this field, is the availability of powerful surface-sensitive analyti-cal/physical techniques. Confining a lipid membrane to the near-surface region of a solid substrate makes it possible to study its structural and functional properties in detail using a variety of techniques such as surface plasmon resonance, AFM, TIRF, attenuated total reflection, and sum frequency vibrational spectroscopy [38 -2]. 

Miranda P B and Shen Y R 1999 Liquid interfaces a study by sum-frequency vibrational spectroscopy J. Rhys. Chem. B 103 3292-307... 

In another study which used a support more relevant to supported ionic liquid catalysts, sum-frequency vibrational spectroscopy (SFVS) was used to study the structure of ionic liquid cations present at the interface between a silica support and imidazolium ionic liquids [RMIM][X], with R = hex)d, oct)4 or decyl, and X = (CF3(CF2) S02)2N with = 0 or 1 [46]. The measurements were performed by introducing the ionic liquids in a thoroughly cleaned fused silica prism. 

Fig. 5.6-2 Schematic illustration of the orientation of imidazolium cations at the surface of silica determined by sum-frequency vibrational spectroscopy [45],...

Fitchett, B.D. and Conboy, ).C. (2004) Stmcture of the room-temperature ionic liquid/SiOj interface studied by sum-frequency vibrational spectroscopy. J. Phys. Chem. B, 108, 20255-20262. 

Shen, Y.R. and Ostroverkhov, V. 2006. Sum-frequency vibrational spectroscopy on water interfaces Polar orientation of water molecules at interfaces. Chem. Rev. 106 1140-1154. 

M. Oh-e, H. Yokoyama, S. Yorozuya, K. Akagi, M. A. Belkin, Y. R Shen, Chirality probed by sum-frequency vibrational spectroscopy for hehcaUy structured conjugated hquid crystaUine polymers. Mol. Cryst. Liq. Cryst., 436, 73-81 (2005). 

Abstract Vibrational sum-frequency spectroscopy in conjunction with interfacial pressure measurements are used to provide the first direct spectroscopic information about the structure of amphiphillic molecules adsorbed to the interface between two immiscible liquids by total internal reflection sum-frequency vibrational spectroscopy (TIR SFVS). The effect of the ionic head group on the conformational order of sodium dodecyl sulfate (SDS), sodium dodecylsulfonate (DDS), dodecyltrimethylammonium chloride (DTAC), and dodecylamine hydrochloride (DAC) adsorbed at the D2O/CCI4 interface has been examined. In addition, the effect of the length of the alkyl chain on the conformation and orientation of sodium hexylsulfonate (HS), sodium undecylsulfonate (UDS), and sodium dodecylsulfonate (DDS) is also presented. SF vibrational spectra indicate the presence of gauche conformations in the hydrocarbon chains of all the surfactants examined. An increase in the surface coverage results in the reduction of gauche defects in the hydrocarbon chains as determined from the intensity ratio of the methyl to methylene symmetric... 

Direct orientation measurements of the methylene tail in amphiphilic monolayers are limited and have only been accomplished with vibrational spectroscopy. Sum-frequency vibrational spectroscopy (SFG) is surface specific and suitable for amphiphilic monolayer studies. Conformation and orientation information may be obtained from the peak intensities. SFG... 

The supersolid skin contains molecules upto two layers. A comparative study using x-ray and neutron scattering, sum-frequency vibrational spectroscopy and calorimetric measurements of the interaction between water and hydrophobic surface, as well as molecular-statistical calculations of the state of water molecules in the skin prove that the boundary water layer in the vicinity of hydrophobic surface consists of a thin ( 0.5 nm) depletion layer. The density is as low as 0.4 g/cm (correspond to doo = 3.66 A) and a considerable amount (25-30 %) of water molecules with free OH groups, which is characterized by a more ordered network of H-bonds compared to liquid water [22, 23]. 

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