Inelastic scattering experiments

Radiation probes such as neutrons, x-rays and visible light are used to see the structure of physical systems through elastic scattering experiments. Inelastic scattering experiments measure both the structural and dynamical correlations that exist in a physical system. For a system which is in thermodynamic equilibrium, the molecular dynamics create spatio-temporal correlations which are the manifestation of thermal fluctuations around the equilibrium state. For a condensed phase system, dynamical correlations are intimately linked to its structure. For systems in equilibrium, linear response theory is an appropriate framework to use to inquire on the spatio-temporal correlations resulting from thermod5mamic fluctuations. Appropriate response and correlation functions emerge naturally in this framework, and the role of theory is to understand these correlation functions from first principles. This is the subject of section A3.3.2. 

In the next section we discuss linear hydrodynamics and its role in understanding the inelastic light scattering experiments from liquids, by calculating the density-density correlation fiinction,. Spp. 

Out of the five hydrodynamic modes, the polarized inelastic light scattering experiment can probe only the tliree modes represented by equation (A3.3.18), equation (A3.3.19) and equation (A3.3.20). The other two modes, which are in equation (A3.3.17), decouple from the density fluctuations diese are due to transverse... 

Bodo E, Gianturco F A and Paesani F 2000 Testing intermolecular potentials with scattering experiments He-CO rotationally inelastic collisions Z. Phys. Chem., A/F214 1013-34... 

Laser-based methods of identification are extremely powerful they are able to provide species and structural information, as well as accurate system temperature values. Spontaneous Raman scattering experiments are useful for detection of the major species present in the system. Raman scattering is the result of an inelastic collision process between the photons and the molecule, allowing light to excite the molecule into a virtual state. The scattered light is either weaker (Stokes shifted) or... 

As will be shown in Section 3, inelastic X-ray scattering experiments can help to decide which theoretical approach is appropriate. One must keep in mind that this static correction is far from an appropriate description of electron correlations. A more accurate way is to account for dynamical screening by writing %(q, co) in terms of the one-particle Greens function G(p, e) corrected for many-particle effects by a... 

Inelastic X-ray scattering experiments on lithium and liquid aluminum... 

To conclude, we have demonstrated how inelastic X-ray scattering experiments, both for small and large momentum transfer, can provide information about electron-electron correlation and lattice effects on correlation. 

Raman spectroscopy is an inelastic light scattering experiment for which the intensity depends on the amplitude of the polarizability variation associated with the molecular vibration under consideration. The polarizability variation is represented by a second-rank tensor, oiXyZ, the Raman tensor. Information about orientation arises because the intensity of the scattered light depends on the orientation of the Raman tensor with respect to the polarization directions of the electric fields of the incident and scattered light. Like IR spectroscopy, Raman... 

Highly energetic compounds with potential use in explosive devices must be characterized completely and safely, particularly as the explosive character may be linked directly to vibrational modes in the molecular structure, hence the application of computational methods to complement experimental observations. ANTA 5 has been the subject of various studies and, as an adjunct to one of these and to confirm the results of an inelastic neutron scattering experiment, an isolated molecule calculation was carried out using the 6-311G basis set <2005CPL(403)329>. 

Lastly, we mention one more excitation mechanism that has been observed in molecules. It is well-established that following strong field ionization in atoms and molecules, under certain conditions, the ionized electron can be driven back to the ion core where it can recombine to produce high-harmonic radiation, induce further ionization, or experience inelastic scattering. However, there is also the possibility of collisional excitation. Such excitation was observed in [43] in N2 and O2. In both molecules, one electron is tunnel ionized by the strong laser field. When the electron rescatters with the ion core, it can collisionally ionize and excite the molecular ion, creating either N + or Ol+ in an excited state. When the double ion dissociates, its initial state can... 

The usefulness of potential energy hypersurfaces in describing reaction dynamics and chemical reactivity is well illustrated by Levine and Bernstein [84] and Shaik et al. [85] books. See also the fundamental paper of Hase [86]. This success does not assure that the coordinate representation of quantum system is necessarily truthful. It goes without saying, the coordinate representation is an extremely useful mathematical model. However, from recent inelastic neutron scattering experiments on hydrogen bonded system, the idea that the BO approximation may be inadequate has been advanced by Kearley and coworkers[87]. 

Figure 3.19. Variation of the energy transfer into the surface in scattering of NO from Ag(l 11) as a function of Ee = f ccsO,-. Solid lines and solid points are for rotationally elastic scattering. /, = Jj = 0.5 and the open points are for non-state-resolved scattering experiments (and therefore also contains a contribution from rotationally inelastic scattering). From Ref. [181].

Because there is no general microscopic theory of liquids, the analysis of inelastic neutron scattering experiments must proceed on the basis of model calculations. Recently1 we have derived a simple interpolation model for single particle motions in simple liquids. This derivation, which was based on the correlation function formalism, depends on dispersion relation and sum rule arguments and the assumption of simple exponential decay for the damping function. According to the model, the linear response in the displacement, yft), satisfies the equation... 

Inelastic neutron scattering experiments have been used to study the ground state splitting of singly bridged dichromium(III) complexes of... 

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