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111.
A block considered as a set of elements together with its adjacency matrix A is called a C-block if A is the adjacency matrix of a circuit. A balanced circuit design with parameters v, b, r, k, λ (briefly, BCD(v, k, λ)) is an arrangement of v elements into bC-blocks such that each C-block contains k elements, each element occurs in exactly rC-blocks and any two distinct elements are linked in exactly λ C-blocks.We investigate conditions for the existence of BCD and show, in particular, that if the block-size k ? 6 and the trivial necessary conditions are satisfied, then the corresponding BCD exists. 相似文献
112.
We report an electron diffraction study of the molecular structure of gaseous cesium and thallium sulphates and cesium molybdate and tungstate. The average structure found for the M2XO4 molecules is described by a model (symmetry D2d) in which the metal atoms bridge two edges of an XO4 tetrahedron to form two 4-membered mutually perpendicular planar MO2X rings.The data lead to conclusions on the complex nature of intramolecular motion. This motion may roughly correspond to great displacements of metal atoms on the surface of an imaginary sphere described near the tetrahedral acid residue. 相似文献
113.
H.P. Dhar 《Surface science》1977,66(2):449-462
Reflectance changes at lead electrodes have been measured as a function of surface charge at 45° and 70° angles of incidence using solutions of sodium fluoride and quaternary ammonium salts. These solutions were chosen so as to provide quite different composition for the inner layer at the metal/solution interface, and hence different optical contributions there from. Linear reflectance-surface charge relation has been observed for NaF solutions only at a number of wavelengths. The optical effects from the inner layer has been recognized but could not be separated out from the main er effect by comparative measurements at two angles of incidence. This has been rationalized on the basis of similar variation of the er effect and the optical effect from the double-layer as a function of angle of incidence of light. 相似文献
114.
It is shown that, under certain conditions, the use of Mulliken gross atom populations for the analysis of molecular electronic wavefunctions is not without a basis in the rigorous probabilistic interpretation of quantum mechanics, 相似文献
115.
Molecular quantum beats are shown for the case of biacetyl, to vary strongly under the influence of weak magnetic fields. Values for dephasing constants for a gas-phase molecular system were determined. Information on sub-Doppler level splittings in the intersystem-crossing process is obtained. 相似文献
116.
L. Bezur J. Marshall J.M. Ottaway 《Spectrochimica Acta Part B: Atomic Spectroscopy》1984,39(6):787-805
A square-wave wavelength modulation system, based on a rotating quartz chopper with four quadrants of different thicknesses, has been developed and evaluated as a method for automatic background correction in carbon furnace atomic emission spectrometry. Accurate background correction is achieved for the residual black body radiation (Rayleigh scatter) from the tube wall and Mie scatter from particles generated by a sample matrix and formed by condensation of atoms in the optical path. Intensity modulation caused by overlap at the edges of the quartz plates and by the divergence of the optical beam at the position of the modulation chopper has been investigated and is likely to be small. 相似文献
117.
The paramagnetic BrO2 molecule with lifetime τ > 10 s has been found amoung the products of the O + Br2 reaction in a discharge flow system. Identification was made by the technique of molecular beam focusing in an inhomogeneous magnetic field with mass-spectrometric detection. Its symmetry appeared to be C2, like the stable OClO molecule, as was determined by focusing in an inhomogeneous electric field. Approximate rate constants for the reactions O + BrO2 (k3 = (2.5–6)×10?12 cm3/s) and Br + BrO2 (k7 = 5 × 10?11 cm3/s) were obtained. 相似文献
118.
Mikio Yagi Nobuyuki Nishi Minoru Kinoshita Saburo Nagakura 《Chemical physics letters》1976,39(2):240-244
Using microwave induced delayed phosphorescence techniques we determined the populating and depopulating rate constants for the individual spin-sublevels of the phosphorescent states of tetracyanobenzene (TCNB) and its charge-transfer complexes with benzene and hexamethylbenzene (HMB) in n-hexane at 1.25 K. It was shown that the non-radiative decay process from the shortest lifetime sublevel is most responsible for the previously observed shortening in the phosphorescence lifetime of the TCNBHMB complex. 相似文献
119.
S. Clough 《Chemical physics letters》1981,80(2):389-392
A series of experiments is discussed which, it has been claimed, demonstrate that hindered methyl groups exist at room temperature as relatively long-lived proton spin symmetry species. It is concluded that this concept lacks a theoretical foundation, conflicts with the model of random hopping reorientation between localised states, and leads to physically implausible predictions. 相似文献
120.
The fluorescence, excitation and absorption spectra and fluorescence decay kinetics of charge-transfer (CT) complexes and exciplexes ofheteroaromatic cations and some other electron acceptors were investigated in ethanol at 77 K. Experimental data indicate that the fluorescence state of the exciplex may differ from that of the CT complex. 相似文献