Inelastic phase analysis

Jaduszliwer, B. and Paul, D.A.L. (1974). Elastic scattering of positrons in neon and argon and phase shift analysis from 4 eV to inelastic thresholds. Can. 

Because all phases of the interaction of the incident energetic ion beam with materials, including kinematics and cross section of the elastic collision and the energy losses by means of inelastic interaction with the electrons are readily calculable, the analysis lends itself to computer simluation. One of the first such programs, developed at IBM (4), is used at NRL, while other programs have also been developed at a number of other laboratories. 

The exchange of energy between an oscillator and a simple molecule was first analyzed from a classical viewpoint by I andau and Teller, who showed that, for a very slow collision, the net inelastic transfer is zero. This can be seen intuitively by considering the behavior of an infinitesimal and nearly constant force applied to one atom of a vibrating molecule. On one half cycle when the force and motion are in phase there will be an increase in momentum and kinetic energy of this atom which will be almost precisely compensated in the next half cycle by a decrease in momentum and kinetic energy. Closer analysis shows that the net effect of such a force over a cycle is to slowly accelerate the entire oscillator but not to excite it. The probability of inelastic transfer increases with the hard-ness of the collision. This latter is measured by the ratio of the time of a vibration to the collision time, rtr/rcoii = Vnl Tva, where intermolecular forces/ v is the oscillator frequency, and Vr is the relative collision velocity. 

Photoelectron spectroscopy of valence and core electrons in solids has been useful in the study of the surface properties of transition metals and other solid-phase materials. When photoelectron spectroscopy is performed on a solid sample, an additional step that must be considered is the escape of the resultant photoelectron from the bulk. The analysis can only be performed as deep as the electrons can escape from the bulk and then be detected. The escape depth is dependent upon the inelastic mean free path of the electrons, determined by electron-electron and electron-phonon collisions, which varies with photoelectron kinetic energy. The depth that can be probed is on the order of about 5-50 A, which makes this spectroscopy actually a surface-sensitive technique rather than a probe of the bulk properties of a material. Because photoelectron spectroscopy only probes such a thin layer, analysis of bulk materials, absorbed molecules, or thin films must be performed in ultrahigh vacuum (<10 torr) to prevent interference from contaminants that may adhere to the surface. 

The unit cell group description of the normal modes of vibration within a unit cell, many of which are degenerate, given above is adequate for the interpretation of IR or Raman spectra. The complete interpretation of vibronic spectra or neutron inelastic scattering data requires a more generalized type of analysis that can handle 30N (N=number of unit cells) normal modes of the crystal. The vibrations, resulting from interactions between different unit cells, correspond to running lattice waves, in which the motions of the elementary unit cells may not be in phase, if ky O. Vibrational wavefunctions of the crystal at vector position (r+t ) are described by Bloch wavefunctions of the form [102]... 

The most important experimental techniques in this field are structural analyses by both X-ray and neutron diffraction methods, and infrared and Raman spectroscopic measurements. Less frequently used techniques are nuclear magnetic resonance, both broad band NMR spectroscopy and magic angle spinning methods (MAS), nuclear quadrupole resonance (NQR), inelastic and quasielastic neutron scattering, conductivity and permittivity measurements as well as thermal analyses such as difference thermal analysis (DTA), differential scanning calorimetry (DSC), and thermogravimetry (TG and DTG) for phase transition studies. 

When an atomic primary ion of 10-25 keV impacts on a solid, it penetrates into the sample over a distance of typically 10-50 nm and dissipates its energy by inelastic collisions with the sample atoms along its trajectory. The resulting displacement of atoms and destruction of the molecular structure start a complex series of electronic, vibrational, and ultrafast thermal processes that finally cause electrons, atoms, and intact molecules, radicals, and secondary ions to be set free from the upper monolayer(s). Depending on the composition of the analyte and matrix, the ratio fsiMS of directly emitted secondary ions over neutrals may range from 10 to 10. These large differences in fsiMS and detection sensitivity severely hamper the application of SIMS for survey analysis. In contrast, the relative abundance of sputtered neutrals remains relatively constant (i.e., 99 and 99.9999% for Isims of 10 and 10, respectively). On the condition that the gas-phase ionization step... 

BordaUo HN, Zakharov BA, Boldyreva EV, Johnson MR, Koza MM, Seydel T, Fischer J (2012) Application of incoherent inelastic neutron scattering in pharmaceutical analysis relaxation dynamics in phenacetin. Mol Pharm 9 2434-2441 Bptker JP, Karmwar P, Strachan CJ, Cornett C, Tian F, Zujovic Z, Rantanen J, Rades T (2011) Assessment of crystalline disorder in cryo-milled samples of indomethacin using atomic pairwise distribution functions. Int J Pharm 417 112-119 Boutonnet-Fagegaltier N, Menegotto J, Lamure A, Duplaa H, Caron A, Lacabanne C, Bauer M (2002) Molecular mobihty study of amorphous and crystalline phases of a pharmaceutical product by thermally stimulated current spectrometry. J Pharm Sci 91 1548-1560 Bras AR, Noronha JP, Antunes AMM, Cardoso MM, Schdnhals A, Affouard Fdr, Dionfsio M, Correia NIT (2008) Molecular motions in amorphous ibuprofen as studied by broadband dielectric spectroscopy. J Phys Chem B 112 11087-11099... 

Fig. 40. The linewidth as function of temperature for YbPdjSij. Open (soUd) symbols represent the quasielastic (inelastic) linewidths. The circles correspond to analysis of spectra taken with Ej = 3.l meV, the triangles to 12.5 meV, and the squares to 50meV. The different lines through the points are simply guides to the eye. The lower dashed line is the quasielastic width associated with the impurity phase. (From Weber et al. 1989b.)...

C. J. Hogan, E. Folta-Stogniev, B. Ruotolo, J. Fernandez de la Mora, IMS-MS study of native aggregates, from insulin to GroEL. To be submitted to Anal. Chem. 2009 Hogan, C., Ruotolo, B., Robinson, C., Fernandez de la Mora, J. Tandem differential mobility analysis-mass spectrometry of the GroEL complex Structure compaction in the gas phase and inelastic air-protein interaction, Submitted to J. Phys. Chem. B, 2010. 

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