Particle spectra

Trimborn et al. (2000) describe a four-week field campaign to characterise an aerosol in a particular area, where the LAMPAS 2 instrument was continuously analysing the size and composition of individual particles in five size ranges between 0.2 pm and 1.5 pm. Some 10,000 single particle spectra were recorded during the measuring period, and one example of these is shown in Figure 3.13. 

Fig. 9.3. Proton and a-particle spectra of primary cosmic rays and their demodulated versions. After Goldstein et al. (1970). Courtesy Reuven Ramaty.

Absorptions near 2910 and 1420 cm 1 have been assigned to the di-cr complex (96, 57), probably adsorbed on (111) facets because of its transformation at higher temperatures into ethylidyne, (CH3C)M3 (see below). Other modes of the di-cr complex on (111) (Table V) are not observed because of the alumina cutoff. It is of interest that, unlike the case of the 7t-complex, no additional absorptions for the di-cr complex are observed in the small-particle spectra due to relaxation of the MSSR. However, the it complexes may well be adsorbed on step or comer sites as this species is only found on the corrugated (110) and (210) surfaces on single-crystal Pt (147-154). For the di-cr species, probably on flat (111) terraces, the operation of the MSSR would be expected to be more pronounced for a given mean particle size. 

We present the resulting calculations of single-particle spectra for four electrons (2 of each spin direction) on a linear ring of four sites. The singleparticle single-band Hamiltonian describing the non-interacting system is... 

Figures 1 shows, for U = 10.0, the single-particle spectra for four electrons on a ring of four sites (half-filled band) obtained in the ordinary version of HF...

Figure 1 Single-particle spectra for a ring with four sites with U = 10.0. The solid line is the spectrum calculated from the restricted HF while the dashed line is the spectrum obtained with the 2HF, and the dotted line is the exact spectrum.

The experimental determination of the density of states is not an easy task. Considering vibronic regions, n( ) may be measured indirectly in the 0-1 transitions (two-particle spectra, as discussed in Section II.B) or in 1-0 transitions (hot bands). 

Since spontaneous fission is extremely rare in Nature, detection of fission events in natural samples would give a strong hint. Alpha-particle spectra would be less specific, because the energies predicted for superheavy nuclei fell into the range covered by the natural decay series deriving from uranium... 

One way of measuring the gap G, in insulators, consists in superposing direct and inverse photoemission spectra (quasi-particle spectra of the compound), and recording the smallest energy difference between them. G is thus related to the ionization potential and electron affinity by ... 

The chemical industry, which had been in existence since very early times in the form of factories for the purification of salts and the smelting and refining of metals, expanded as methods for the preparation of relatively pure materials became more common. In 1896, Becquerel discovered radioactivity, and another area of study was opened. Studies of subatomic particles, spectra, and electricity finally led to the atomic theory of Bohr in 1913, which was soon modified by the quantum mechanics of Schrodinger and Heisenberg in 1926 and 1927. 

Mixtures of beta-particle-emitting nuclides of more than one element usually have overlapping spectra. This is also often true for alpha-particle-emitting nuclides. Some of these mixtures can be analyzed by ICP-MS without internal interferences. For example, the alpha-particle spectra of " Np and Pu partially overlap even under the best of conditions, whereas ICP-MS is appropriate for analysing the long-lived... 

Bland, C.J., Truffy, J. and de Bruyne, T., Deconvolution of alpha-particle spectra to obtain plutonium isotopic ratios. Appl. Radiat. Isot., 43 (1992) 201-209. 

Bortels, G. and Collaers, P.J., Analytical functions for fitting peaks in alpha-particle spectra. Int. J. Appl. Radiat. Isotop., 38 (1987) 831. 

Mason GM, Dwyer JR, Mazitr JE (2000) New properties of He-rich solar flares dedcued from low-energy particle spectra. Astrophys J Lett 545 L157-L160... 

The described relativistic effects on the Kohn-Sham states form the background for a quantitative understanding of ground state properties like atomic volumes, structural properties and magnetic properties discussed in the following two sections. Quasi-particle spectra, on the other hand, are only in certain cases reasonably well approximated by the Kohn-Sham densities of states (so-called weakly correlated systems). In general, Kohn-Sham spectra and quasi-particle spectra may considerably deviate from each other. Nonetheless, they show the same symmetry. Thus, spin-orbit related splittings in... 

Because alpha-particle spectra consist of characteristic, discrete energy peaks, they are quite useful for identification. Pulse-height analyzers (.Section I2B-S) permit the recording of alpha-particle spectra. 

The particle spectra were purposely taken with overlap, both to check the correspondence among apertures and in an attempt to provide continuous spectra over a large range of particle diameters. The spectra for the original plots represented the average results of three to five runs... 

Figure 2.5. Three typical beta-particle spectra. (Data from ICRU 1997, pp. 107-108.)...

Fig. 10.9. (a) Calculated optical absorption spectrum of (rans-polyacetylene from a DFT-GWA-BSE calculation. The solid and dashed curves represent the exciton and quasi-particle spectra, respectively, (b) The electron-hole distribution function. Reprinted with permission from M. Rohlfing and S. G. Louie, Phys. Rev. Lett., 82, 1959, 1999. Cop5rright 1999 by the American Physical Society. 

For spectral analysis below 2000cm , FTIR transmission spectra were obtained. A small amount of sample (approximately 10-20 mg) was placed between two NaCl plates, which were then rotated to disperse the particles. Spectra were obtained at 4 cm nominal resolution with a DTGS detector by co-addition of 16 scans. 

A study of the superheavy region with self-consistent mean field models (employing mean field and Skyrme-Hartree-Fock approaches) yields different results for predicted regions of stability. O Figure 19.16 displays the single-particle spectra for neutrons and protons (Bender et al. 2001) for Sn, the superheavy nucleus 126, and the hyperheavy nucleus 164. They exhibit a significant difference in the nature of the shells of doubly magic tin (where proton and... 

Single-particle spectra for protons left panels) and neutrons right panels) at spherical shape for different mean-field forces. The small diagrams at the bottom of the right panel show the predicted radial neutron distributions. (Bender et al. 2001)... 

Shell-Correction and Averaging of Single-Particle Spectra for the Modified Nilsson Potential... 

Having obtained the single-particle spectra, the empirical shell correction (in the spirit of Strutinsky s method [38]), is determined from Eq. (14). 

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