Optical model

Spectroscopic dlipsometry is sensitive to the dielectric functions of the different materials used in a layer stack. But it is not a compositional analytical technique. Combination with one of the compositional techniques, e. g. AES or XPS and with XTEM, to furnish information about the vertical structure, can provide valuable additional information enabling creation of a suitable optical model for an unknown complex sample structure. 

Hodgson, P.E. (1963) The Optical Model of Elastic Scattering, Oxford University Press, New York. 

Giant dipole resonance. Isovector giant resonances contain information about the SE through the restoring force. In particular the excitation of the isovector giant dipole resonance (GDR) with isoscalar probes has been used to extract A R/R [32], In the distorted wave Bom approximation optical model analysis of the cross section the neutron and proton transition densities are needed as an input. For example, in the Goldhaber-Teller picture these are... 

It is difficult to make a quantitative estimate of the uncertainty in the result coming from the model dependence of the approach. In the analysis several assumptions must be made, such as the radial shape of the density oscillations and the actual values of the optical model parameters. 

P. Bienstman and R. Baets, Optical modelling of photonic crystals and VCSELs using eigenmode expansion and perfectly matched layers, Opt. Quantum Electron. 33, 327-341 (2001). 

Tozer, W. F., and D. E. Beeson, 1974. Optical model of noctilucent cloud based on polarimetric measurements from two sounding rocket campaigns, J. Geophys. Res., 79, 5607-5612. 

One of the best known and most intensively studied optical models is an oscillator with Kerr nonlinearity. Mutually coupled Kerr oscillators can be successfully used for a study of couplers the systems consist of a pair of coupled Kerr fibers. The first two-mode Kerr coupler was proposed by Jensen [136] and investigated in depth [136,137]. Kerr couplers affected by quantization can... 

In modelling the welding process, an optical model has been used to determine how the laser beam is attenuated in the course of passage. This information has been used as the basic input to a thermal model. 

The x-ray models used have been generated by a Hartree-Slater code [5,6] of J. Scofield s. Radiative recombination rates are calculated from the photoionization crossections. Information for the optical models has been drawn from a wide variety of sources. The ions included in the present calculation are Fel, n, HI, IV, V, VI Col, II, in, IV, V OI, n, HI, IV and Hel, H. Many important ions are not included, particularly in the intermediate Z range near Si. To minimize (but not eliminate) the effects of these... 

In the classical version of the optical model, as developed mainly by Ross and co-workers,35-46-47 each impact parameter b manifests a certain reaction probability P(b), the classical opacity. Although a complex potential as in (11.12) is probably meaningless in a purely classical context, if we use the (rigorous) rate interpretation of T(r), we may derive24... 

The classical theory makes especially clear the inherent ambiguity of data analysis with the optical model, and this ambiguity carries over into the quantum model. If we wish to use experimental differential cross sections to gain information about V0(r) and P(b) or T(r), we must assume a reasonable parametric form for V0(r) that determines the shape of the cross section in the absence of reaction. The value P(b) is then determined [or T(r) chosen] by what is essentially an extrapolation of this parametric form. In the classical picture a V0(r) with a less steep repulsive wall yields a lower reaction probability from the same experimental cross-section data. The pair of functions V0 r), P b) or VQ(r), T(r) is thus underdetermined. The ambiguity may be relieved somewhat (to what extent is not yet known) by fitting several sets of data at different collision energies and, especially, by fitting other types of data such as total elastic and/or reactive cross sections simultaneously. 

As mentioned in Section II.A, the Pgl process is ideal for the application of the optical model. This is clear in the classical and semiclassical Pgl theory,24,25 for which opacity and cross-section formulas are completely equivalent to those given earlier in this chapter. The quantal optical model is also rigorously related to the elastic component of the quantal Pgl theory. Miller49 has shown that T(r), identified in Pgl as the autoionization width of the excited electronic state, may be accurately obtained by a standard Born-Oppenheimer electronic structure calculation as... 

Pittsburgh, for Ne + Ar,Kr,Xe. The absence of structure in the wide-angle intensity is in marked contrast to the He (215) case, with optical model analysis requiring recourse to other types of data, such as total ionization cross sections (see Section III.C.l.c). An immediate conclusion is that the van der Waals repulsion in these systems does not bear the same relation to the attraction as for the alkalis, although the difference is not as great as for He interactions versus those of lithium. 

Microcentrifuge, Eppendorf-type, maximum speed 12,000 to 14,000 rpm Microcentrifuge tubes, 1.5-ml and 0.5-ml Microscope, standard optical model (optionally with epifluorescence or phase-contrast illumination)... 

D. A. Micha. Dynamics of Molecular Collisions, Vol. IA, chapter Optical models in molecular collision theory, page 81. Plenum Press, New York, 1976. 

Joachain, C.J., Vanderpoorten, R., Winters, K.H. and Byron Jr., F.W. (1977). Optical model theory of elastic electron- and positron-argon scattering at intermediate energies. J. Phys. B At. Mol. Phys. 10 227-238. 

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