Inelastic neutron scattering spectroscopy

Supplementary to other vibrational spectroscopies, inelastic neutron scattering (INS) spectroscopy is a very useful technique for studying organic molecules as it is extremely sensitive to the vibrations of hydrogen atoms. INS spectroscopy has been used to analyze the molecular dynamics of the energetic compound ANTA 5 <2005CPL(403)329>. 

M.H. Herzog-Cance, D.J. Jones, R.E1. Mejjad, J. Roziere J. Tomkinson (1992). J. Chem. Soc. Faraday Trans., 88, 2275-2281. Study of ion exchange and intercalation of organic bases in layered substrates by vibrational spectroscopy. Inelastic neutron scattering, infrared and Raman spectroscopies of aniline inserted alpha and gamma zirconium hydrogen phosphates. 

It is important to mimic not only the static structures but also their dynamic properties. Conformational transitions, changes of folds, denaturation, and renaturation of biopolymers can be understood better if lattice dynamics, phase transitions, amor-phization of crystalline amino acids and small peptides are studied and compared with those in synthetic polyaminoacids and in two-dimensional layers at the interfaces. Variable-temperature [44, 64-84] and variable-pressure [29, 81, 82, 85-134] IR- and Raman spectroscopy, inelastic neutron scattering, SAXS, NMR, X-ray and neutron diffraction, DSC are applied to study the structure and dynamics of crystalline amino acids, small peptides, synthetic polymers, interface layers and biopolymers [73-153]. 

Characterize the mobile hydrogen in NaAlH4 by solid state NMR spectroscopy, inelastic neutron scattering, optical spectroscopy and neutron diffraction studies. 

INS photoelectron spectroscopy Inelastic neutron scattering No Yegl ,233,234... 

Experimental bulk moduli can be obtained from the measurement of lattice parameters and volumes as a function of pressure [30]. The single crystal elastic moduli can be measured using the Brillouin spectroscopy, inelastic neutron scattering, ultrasonic measurements or the Schaefer-Bergmann method [31]. Once the single crystal moduli are known one can derive the bulk B and shear G moduli of a polycrystalline material [32]. 

R42 S. Mamone, J. Y.-C. Chen, R. Bhattacharyya, M. H. Levitt, R. G. Lawler, A. J. Horsewill, T. Room, Z. Bade and N. J. Turro, Theory and Spectroscopy of an Incarcarated Quantum Rotor The Infrared Spectroscopy, Inelastic Neutron Scattering and Nuclear Magnetic Resonance of H2 C ) at Cryogenic Temperature , Coord. Chem. Rev., 2011, 255, 938. 

The organization of this chapter is the following. After definition of some physical constants to be kept in mind and an abstract presentation of infrared and Raman spectroscopy, inelastic neutron scattering spectroscopy is featured in Section 2. In Section 3, the long lasting problem of force-field calculation is enlightened by comparison of calculated and observed INS profiles. By direct comparison, unrealistic dynamical models can be eliminated quite safely. 

Methane is one of the best-understood adsorbates in zeolites. By the concomitant application of infrared spectroscopy, inelastic neutron scattering and theoretical studies the interaction of this molecule and its dynamic behaviour have been carefully investigated by Cohen de Lara et al. [114-122]. Chapter 4 deals in detail with neutron scattering studies on this molecule. 

Fig. 6.13 Frequency-scattering vector domeiins of available techniques for dynamic studies. The techniques in the map are Raman spectroscopy, Brillouin spectroscopy, inelastic neutron scattering (INS), inelastic X-ray scattering (IXS), neutron spin-echo spectroscopy, nuclear forward scattering (NFS), XPCS, ultrasmaU-angle X-ray scattering-based XPCS (USAXS XPCS), and DLS [also known as photon correlation spectroscopy (PCS)]...

Vibrational spectroscopy provides detailed infonnation on both structure and dynamics of molecular species. Infrared (IR) and Raman spectroscopy are the most connnonly used methods, and will be covered in detail in this chapter. There exist other methods to obtain vibrational spectra, but those are somewhat more specialized and used less often. They are discussed in other chapters, and include inelastic neutron scattering (INS), helium atom scattering, electron energy loss spectroscopy (EELS), photoelectron spectroscopy, among others. 

At T < tunneling occurs not only in irreversible chemical reactions, but also in spectroscopic splittings. Tunneling eliminates degeneracy and gives rise to tunneling multiplets, which can be detected with various spectroscopic techniques, from inelastic neutron scattering to optical and microwave spectroscopy. The most illustrative examples of this sort are the inversion of the... 

Kearley, G. J., Pressman, H. A. Slade, R. C. T. (1986). The geometry of the HjOJ ion in dodecatungstophosphoric acid hexahydrate, (HjOJ)j (PWjjOfo), studied by inelastic neutron scattering vibrational spectroscopy. Journal of the Chemical Society Chemical Communications, 1801-2. 

Vibrations in molecules or in solid lattices are excited by the absorption of photons (infrared spectroscopy), or by the scattering of photons (Raman spectroscopy), electrons (electron energy loss spectroscopy) or neutrons (inelastic neutron scattering). If the vibration is excited by the interaction of the bond with a wave... 

Only a very few polynuclear complexes containing more than two chromium(III) centers have been studied so far. However, magnetochemical and inelastic neutron scattering studies, heat capacity measurements, and emission spectroscopy have been reported for various tetranuclear species (40,142 151). Two review articles dealing with the spectroscopic and magnetic properties of chromium(III) oligomers have recently appeared (127, 128). 

Neutron spectroscopy (also referred to as inelastic neutron scattering) has been used to measure the extent of guest-host interactions in a hydrate lattice, which help to explain the anomalous thermal behavior of hydrates (e.g., low thermal... 

The final chapters of this book review the progress of three recently developed techniques that provide information about the vibrational states of adsorbed molecules. Perhaps the most important of these techniques is electron energy loss spectroscopy that, despite its inherent low resolution, gives valuable information on vibrational modes that are either inactive in the IR, or inaccessible because of experimental difficulties. The applications of this technique are discussed in two chapters by Somorjai and Weinberg. The review of new experimental techniques concludes with presentations on inelastic electron tunneling spectroscopy and neutron scattering by Kirtley and Taub. 

In this paper we discuss how neutron scattering spectroscopy can be applied to the study of the structure and dynamics of adsorbed molecules. Since reviews of elastic and inelastic neutron scattering from adsorbed films have recently appeared (1.-3), our purpose here is not to present a comprehensive survey of every adsorbed system investigated by neutron scattering. Rather, we shall be concerned primarily with two questions which are basic to the characterization of adsorbed species on catalysts and which have been central to the discussion of this symposium. These are the extent to which the neutron scattering technique can be used to determine 1) the orientation and position of an adsorbed molecule and 2) the strength and location of the forces bonding a molecule to a surface. 

As we shall discuss below, it is also more straightforward to calculate the relative intensity of vibrational modes observed by inelastic neutron scattering than in electron-energy-loss and optical spectroscopies. The relative intensity of the modes, as well as their frequency, can then be used to identify the atomic displacement pattern or eigenvector of the mode. We shall also see through examples of model calculations how the relative intensity of surface vibratory modes is sensitive to the orientation of the adsorbed molecule and the strength and location of its bond to the surface. 

The cross-section in Eq. (1 illustrates another distinguishing feature of inelastic neutron scattering for vibrational spectroscopy, i.e., the absence of dipole and polarizability selection rules. In contrast, it is believed that in optical and inelastic electron surface spectroscopies that a vibrating molecule must possess a net component of a static or induced dipole moment perpendicular to a metal surface in order for the vibrational transition to be observed ( 7,8). This is because dipole moment changes of the vibrating molecule parallel to the surface are canceled by an equal image moment induced in the metal. 

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