Spectroscopy vibrational sum-frequency

Gragson D E and Richmond G I 1998 Investigations of the structure and hydrogen bonding of water molecules at liquid surfaces by vibrational sum frequency spectroscopy J. Phys. Chem. 102 3847... 

Richmond, G. L. (2002) Molecular bonding and interactions at aqueous surface as probed by vibrational sum frequency spectroscopy. Chem. Rev., 102, 2693-2724. 

Successful applications of fourth-order coherent Raman scattering are presented. Interface-selective detection of Raman-active vibrations is now definitely possible at buried interfaces. It can be recognized as a Raman spectroscopy with interface selectivity. Vibrational sum-frequency spectroscopy provides an interface-selective IR spectroscopy in which the vibrational coherence is created in the IR resonant transition. The two interface-selective methods are complementary, as has been experienced with Raman and IR spectroscopy in the bulk. 

J. Kim, G. Kim, and P. S. Cremer, Investigations of water structure at die solid/liquid interface in the presence of supported lipid bilayers by vibrational sum frequency spectroscopy, Langmuir 17, 7255-7260(2001). 

Interface between two liquid solvents — Two liquid solvents can be miscible (e.g., water and ethanol) partially miscible (e.g., water and propylene carbonate), or immiscible (e.g., water and nitrobenzene). Mutual miscibility of the two solvents is connected with the energy of interaction between the solvent molecules, which also determines the width of the phase boundary where the composition varies (Figure) [i]. Molecular dynamic simulation [ii], neutron reflection [iii], vibrational sum frequency spectroscopy [iv], and synchrotron X-ray reflectivity [v] studies have demonstrated that the width of the boundary between two immiscible solvents comprises a contribution from thermally excited capillary waves and intrinsic interfacial structure. Computer calculations and experimental data support the view that the interface between two solvents of very low miscibility is molecularly sharp but with rough protrusions of one solvent into the other (capillary waves), while increasing solvent miscibility leads to the formation of a mixed solvent layer (Figure). In the presence of an electrolyte in both solvent phases, an electrical potential difference can be established at the interface. In the case of two electrolytes with different but constant composition and dissolved in the same solvent, a liquid junction potential is temporarily formed. Equilibrium partition of ions at the - interface between two immiscible electrolyte solutions gives rise to the ion transfer potential, or to the distribution potential, which can be described by the equivalent two-phase Nernst relationship. See also - ion transfer at liquid-liquid interfaces. 

Vibrational sum-frequency spectroscopy (VSFS) is a second-order non-linear optical technique that can directly measure the vibrational spectrum of molecules at an interface. Under the dipole approximation, this second-order non-linear optical technique is uniquely suited to the study of surfaces because it is forbidden in media possessing inversion symmetry. At the interface between two centrosymmetric media there is no inversion centre and sum-frequency generation is allowed. Thus the asynunetric nature of the interface allows a selectivity for interfacial properties at a molecular level that is not inherent in other, linear, surface vibrational spectroscopies such as infrared or Raman spectroscopy. VSFS is related to the more common but optically simpler second harmonic generation process in which both beams are of the same fixed frequency and is also surface-specific. 

Unterhalt H, Rupprechter G, Freund H-J (2002) Vibrational sum frequency spectroscopy on Pd(lll) and supported Pd nanoparticles CO adsorption from ultrahigh vacuum to atmospheric pressure. J Phys Chem B 106 356... 

Wolfrum, K. Laubereau, A. Vibrational sum-frequency spectroscopy of an adsorbed monolayer of hexadecanol on water—destructive interference of adjacent lines. Chem. Phys. Lett. 1994, 228 (1-3), 83. 

Spectroscopic studies of liquid interfaces provide important information about the composition and structure of the interfacial region. Early work was mainly carried out at the solid liquid interface and involved techniques such as neutron and X-ray diffraction, and reflection FTIR spectroscopy. More recently, powerful techniques have been developed to study the liquid liquid and liquid gas interfaces. These studies are especially important because of their relevance to biological systems such as cell membranes. The techniques described here are second-harmonic generation (SHG) and vibrational sum frequency spectroscopy (VSFS). They are both second-order non-linear optical techniques which are specific to the interfacial region. Since the second-order effects involve signals of low intensity, they rely on high-power lasers. 

Experimental study of the double layer is not limited to thermodynamics. A variety of spectroscopic methods have been applied to determine the structure and composition of the double layer. Two of these, namely, second-harmonic generation and vibrational sum frequency spectroscopy, have already been described in section 8.11. Other important techniques are based on the absorption of electromagnetic radiation when it is transmitted through or reflected at the interface. Finally, the scattering of X-rays and neutrons at interfaces has proven to be a valuable tool for obtaining atomic level information about the interface. In the following section some of these methods are outlined in more detail. 

Jubb, A. M., Hua, W., Allen, H. C. (2011). Oi anization of Water and Atmospherically Relevant Ions and Solutes Vibrational Sum Frequency Spectroscopy at the Vapor/Liquid and Liquid/Solid Interfaces, Acc. Chem. Res., 45,110-119. 

Volyak LD, Stepanov VG, Tarlakov YV (1975) Temperature dependence of the angle of contact of water and water-d2 on quartz and sapphire. Zh Fiz Khim 49 2931-3133 Walker DS, Moore FG, Richmond GL (2007) Vibrational sum frequency spectroscopy and molecular dynamics simulations of the carbon tetrachloride-water and 1,2-dichloromethane-water interfaces. J Phys Chem C 111 6103-6112... 

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... 

Vibrational sum frequency spectroscopy in conjunction with interfacial pressure measurements provide the first direct information about the structure of phospholipid monolayers composed of DLPC, DMPC, DPPC, and DSPC, adsorbed to the interface between two immiscible liquids. Temperature controlled experiments carried out with aqueous solutions of DSPC show the lipid bilayer gel to liquid crystalline phase transition temperature to play a pivotal role in determining interfacial monolayer concentration and alkyl chain structure. Even at equivalent interfacial concentrations longer chain phosphocho-line species form more disordered monolayers with a greater number of gauche defects than shorter chain phosphocholine species, as determined from relative intensities of vibrational bands in the CH stretching region. 

Tyrode, E., lohnson, C., Kumpulainen, A., Rutland, M.W., Claesson, PM. Hydration state of nonionic surfactant mono-layers at the hqnid/vapor interface structure determination by vibrational sum frequency spectroscopy. J. Am. Chem. Soc. 127, 16848-16859 (2005). doi 10.102 l/ja053289z... 

Going further into the mechanism and kinetics of mono-layer self-assembly at the mineral-water interface, in situ vibrational sum-frequency spectroscopy (VSFS) has been used to investigate the adsorption, desorption, and equilibrium monomer exchange processes of sodium dodecanoate at the fluorite(CaF2)-water interface. ... 

Viswanath P, Motschmann H (2007) Oriented thiocyanate anions at the air-electrolyte interface and its implications on interfacial water -a vibrational sum frequency spectroscopy study. J Phys Chem C 111(12) 4484... 

One of the most useful of the possible sum-frequency techniques is vibrational sum-frequency spectroscopy in which one of the incident beams is in the infrared spectral region and the other is in the visible region.-" Figure 21-15 shows two configurations that can be used. In Figure 21-15a. the arrangement for studying the interface between two immiscible liquids... 

Kim, J., Kim, G., and Cremer, P. S. 2001. Investigations of water structure at the solid/liquid interface in the presence of supported lipid bUayers by vibrational sum frequency spectroscopy. Langmuir 17 7255. Koenig, B. W., Krueger, S., Orts, W. J., Majkrzak, C. F, Berk, N. F., Silverton, J. V., and Gawrisch, K. 1996. Neutron reflectivity and atomic force microscopy studies of a lipid bilayer in water adsorbed to the surface of a silicon single crystal. Langmuir 12 1343. 

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