Broadband terahertz pulse emission from ZnGeP2

Optical rectification is demonstrated in (110)-cut ZnGeP(2) (ZGP) providing broadband terahertz (THz) generation. The source is compared to both GaP and GaAs over a wavelength range of 1150 nm to 1600 nm and peak-intensity range of 0.5 GW/cm(2) to 40 GW/cm(2). ZGP peak-to-peak field amplitude is larger than in the other materials due to either lower nonlinear absorption or larger second-order nonlinearity. This material is well suited for broadband THz generation across a wide range of infrared excitation wavelengths.     

The Enumeration of Maximally Clustered Permutations

The maximally clustered permutations are characterized by avoiding the classical permutation patterns {3421, 4312, 4321}. This class contains the freely braided permutations and the fully commutative permutations. In this work, we show that the generating functions for certain fully commutative pattern classes can be transformed to give generating functions for the corresponding freely braided and maximally clustered pattern classes. Moreover, this transformation of generating functions is rational. As a result, we obtain enumerative formulas for the pattern classes mentioned above as well as the corresponding hexagon-avoiding pattern classes where the hexagon-avoiding permutations are characterized by avoiding {46718235, 46781235, 56718234, 56781234}.     

Spin-dependent level density in interacting boson-fermion-fermion model

Yield curves for the production of^117g In,^117m In,^116m1In,^115m In,^113m In,¹¹¹In,^110h In,^110l In,¹⁰⁹In,^108hIn and^108lIn from enriches¹¹⁸Sn have been measured by the activation method in the energy region 75–800 MeV. The cross sections have been deduced and for¹¹⁷In,¹¹⁰In and¹⁰⁸In isomeric cross section ratios have been determined. The experimental cross sections are compared to calculations with a cascade-evaporation model and to cross sections calculated with a semi-empirical formula. The isomeric ratios are compared to calculations based on the statistical formalism by Huizenga and Vandenbosch together with cascade-evaporation theory. The (γ, p) cross section and isomeric ratio are also compared to calculations based on a direct knock-out formalism.     

X-Ray photoelectron spectrum of methylisocyanide gas

The C and N 1s spectra of methylisocyanide gas have been recorded. Two resolvable peaks of equal intensity are observed in the C 1s spectrum. Using the equivalent-cores approximation and thermochemical data, together with MNDO MO calculations and the point-charge potential model, the lower-binding-energy C 1s line is assigned to photo-emission from the isocyano carbon. The strong satellites which have been observed in the spectra of coordination complexes of alkyl and aryl isocyanides are not observed in the spectra of the free molecule. Comparisons of the point-charge-potential-corrected binding energies for C 1s and N 1s photoemissions from CH₃NC and its isomer CH₃CN with those for a host of other molecules show that photoemissions from the internal atoms in these molecules are accompanied by substantially less than average relaxation energies. These smaller relaxation energies can be understood using valence-bond theory.     

Gas phase and solid state X-ray photoelectron spectra of the substituted acetylenes (SF5)n C2 (CF3)2−n (n = 0, 1, 2): A comparison of the pentafluorosulfur and trifluoromethyl groups

The core level X-ray photoelectron spectra (XPS) of CF₃CCCF₃, CF₃CCSF₅ and SF₅CCSF₅ have been measured in the solid state. Gas phase spectra of CF₃CCCF₃ and CF₃CCSF₅ have also been obtained. The XPS data, interpreted with the point charge potential model and semiempirical MNDO (minimum neglect of differential overlap) molecular orbital calculations, indicate that the electron withdrawing effect of the ?CF₃ group is greater than that of the ?SF₅ group. Results further suggest that sulfur 3d orbitals do not play a detectable role in the bonding or charge distribution in these molecules. Carbon 1s linewidths of ?CF₃ carbon atoms are found to be much narrower than those arising from the acetylenic carbon atoms. The narrower lines correlate with the much higher binding energy of the ?CF₃ carbon atoms. Large shifts (nearly 1 eV) in heteroatom core level binding energy differences (for example, F 1s — C 1s) between the gas phase and solid state data are observed. These shifts are attributed to solid state effects (Madelung potential, intermolecular bonding interactions, and/or extramolecular relaxation contributions). From these comparisons it is clear that solid state effects are not uniform in their influence on the photoionized sites in these molecules.     

Odd-odd nucleus198Au as first test of IBFFM (OTQM)

The potential used was motivated by collective motion in nuclear physics. A large number of numerical results have been organized into E-τ plots, whose branchings and topology have been studied. Several general rules are inferred.     

Simple method for identification of skeletons of aporphine alkaloids from 13C NMR data using artificial neural networks

This paper describes the use of artificial neural networks as a theoretical tool in the structural determination of alkaloids from (13)C NMR chemical shift data, aiming to identify skeletal types of those compounds. For that, 162 aporphine alkaloids belonging to 12 different skeletons were codified with their respective (13)C NMR chemical shifts. Each skeleton pertaining to aporphine alkaloid type was used as output, and the (13)C NMR chemical shifts were used as input data of the net. Analyzing the obtained results, one can then affirm the skeleton to which each one of these compounds belongs with high degree of confidence (over 97%). The relation between the correlation coefficient and the number of epochs and the architecture of net (3-layer MLP or 4-layer MLP) were analyzed, too. The analysis showed that the results predicted by the 3-layer MLP networks trained with a number of the epochs higher than 900 epochs are the best ones. The artificial neural nets were shown to be a simple and efficient tool to solve structural elucidation problems making use of (13)C NMR chemical shift data, even when a similarity between the searched skeletons occurs, offering fast and accurate results to identification of skeletons of organic compounds.     

A general treatment of the configuration statistics of polysaccharides.

A treatment of the configurational statistics of polysaccharides is given in the isomeric state approximation. All classes of linear polysaccharides of specifiec chemical sequence are treated simultaneously. Chain tortuosity arising from torsional motions about the chemical bonds of the glycosidic linkages is recognized explicitly as is the possibility for conformational isomerism of the sugar residues. Valence angles and lengths are taken to be fixed at the equilibrium values, and pyranose residues in their chair conformations are treated as inflexible constituents of the skeletal structure. Pyranose and furanose forms capable of pseudorotation may be incorporated as rigid skeletal entities as well, provided suitable attention is given to the selection and interpretation of the conformational isomeric states included. Separation of the configuration energy into independent contributions is shown to be impossible in general. Methods are described for assessing the influence of neighbor interactions on the populations of the several conformers of the sugar residues. The relative conformational free energy of the flexible and chair form conformers of pyranose sugars is discussed, and appropriate measures of polysaccharide chain flexibility and stiffness are suggested.     

The[g 9 2/2 ]8+ state in96Zr

An 8⁺ state has been identified at 4390 keV in the doubly semi-magic nucleus⁹⁶Zr through the study of angular correlations among the γ radiation which is emitted in the β^? decay of the 10 s isomer of⁹⁶Y. This state probably has the configuration πg ₉ ^2/2 and is populated through a GT decay from the 8⁺ member of the [πg_9/2?νg_7/2] multiplet in⁹⁶Y. The deexcitation indicates that it belongs to a band based on the 0⁺ state in⁹⁶Zr.