Cross sections relative

Fig. 9. Scofield s x-ray photoionization cross-section relative to that for C electrons as a function of atomic number (19).

Fig. 10. Comparison of Scofield s calculated x-ray photoionization cross-sections relative to that for F 1 electrons and experimental values (22) as a...

They gave the cross-section relative to that of sodium nitrate. The experiments were all performed using a bihyperboloidal electrodynamic levitator. 

Fig. 4.29. Angle-resolved positronium formation cross sections, relative to those at 0°, for positron-argon and positron-krypton collisions at impact energies of 75 eV, 90 eV and f20 eV (Falke et al., 1997). The curves are from the theoretical work of McAlinden and Walters (1994). Reprinted from Journal of Physics, B30, Falke et al., Differential Ps-formation and impact-ionization cross sections for positron scattering on Ar and Kr atoms, 3247-3256, copyright 1997, with permission from IOP Publishing.

Frame (c) shows the next most complex organic molecule containing a polar atom, an atom with at least one unpaired electron. This unpaired electron is in the ground or neutral state. Its energy level can be precisely defined as in (a) and is shown as the narrow n-band in (c). Excitation of this electron is difficult in dilute solution because of its low absorption cross section relative to the other bands. 

If there is more than one polar atom in the molecule, conjugate carbon chemistry and Pauli s rules force the unexcited electrons associated with these atoms into different individual energy bands. These bands remain difficult to detect because of their low absorption cross section relative to the other bands. 

We elected to study coherent up-pumping dynamics in solution-phase metal-hexacarbonyl systems because of their strong vibrational infrared absorption cross sections, relatively simple ground-state spectra, and small (ca. 15 cm ) anharmonic overtone shifts. It was felt that these systems are ideal candidates to demonstrate that population control could be achieved for polyatomic species in solution because the excited state population... 

Corrected peak area using photoelectric cross-sections relative to C Is. 

Figure 1.13 Corrections to the photoproduction cross-section relative to the point-charge value in the field of different nuclei. The nuclei are described by homogeneously charged spheres with R = 1.12 A1/3 fm, with A taken from the table of elements.

Fig. 2. The pathways for collision-induced intramolecular vibrational energy transfer from the 6 level of benzene. The figures entered are the cross-sections relative to the hard sphere collision cross-section. Collision partner He.

Magnets with large cross sections (relative to the cavity cross section) were selected and, as a result, the magnetic field was considered to be constant over... 

As a first example for illustrating the application of Raman spectroscopy in characteri2ing the orientation of surface species, we consider pyridine adsorption on an Ag surface [84], for several reasons. The first SERS experiment was carried out using pyridine as the adsorbed species. Secondly, pyridine has a large Raman cross section, relatively simple molecular structure, and a good assignment of bands appearing in its normal Raman spectrum and SER spectrum. Thirdly, pyridine is an excellent model molecule for surface coordination studies. Eourthly, interactions of the pyridine molecule with the metal surface involve both the it and lone-pair electrons. 

The assumption that the activation cross section varies with neutron energy as 1/v in the thermal neutron region is valid for most (n,y) reactions. The two reactions that deviate the most from the 1/v assumption are Lu(n,y) Lu (typically +0.4%/K) and Eu(n,y) Eu (typically —0.1%/K). The reaction rates for these two reactions, relative to a monitor reaction like Au(n,y) Au, will depend on the thermal neutron temperature in the irradiation channel used. A new set of equations, the Westcott formalism (Westcott 1955), was developed to account for these cases and used the Westcott g T ) factor, which is a measure of the variation of the effective thermal neutron activation cross-section relative to that of a 1/v reaction. In the modified Westcott formalism, the following differences are also included the Qo(a) value of the Hogdahl formalism is replaced by the So(< ) value, and the thermal to epithermal flux ratio, f, is replaced by the modified spectral index, r a) TJTo). To use this formalism with the kg method (De Corte et al. 1994), it is necessary to measure the neutron temperature, r , for each irradiation and a Lu temperature monitor should be irradiated. The Westcott formalism needs to be implemented only when analyzing for Lu and Eu. There are several other non-1/v nuclides Rh, In, Dy, Ir, and Ir, but for these the error... 

Table HI lists the neutron absoiption cross sections for many of the metals described above, as well as their cross section relative to the typical reactor material, zirconium. Materials with a very large cross section relative to zirconium would result in a reduction in the thermal utilization factor f and hence a reduction in Nff. Consequently, Ta, W, V, Mo and Ni based alloys would be impractical choices for a reactor core. From this literature survey, it appears that Fecralloy would provide the greatest promise as a containment material for liquid lead. In addition Tantiron may be an alternate choice. More extensive studies on the applicability of inhibitors such as Ti should be undertaken to determine their affect on the corrosion resistance of these materials. 

Element Atomic Capture Cross-section (b) Cross-section relative toZr... 

Fig. 36-4 A fiber of refractive-index profile n (r) is bent into an arc of constant radius. Polar coordinates (r, (j)) describe the fiber cross-section relative to 0, where the COy-axis is parallel to the plane of the bend.

Energy spectrum dependent capture cross sections relative to the U235 fission cross section play a role in accident scenarios... 

Direct determination of absolute Raman differential cross sections is quite difficult and tedious work often leading to incorrect results. It is easier to measure cross sections relative to some standard. The absolute differential Raman scattering cross sections of the sample can then be straightforwardly obtained. 

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