A data-driven energy ecan in the immediate vicinity of the 7 pair production tbreshold has been performed using the Beijing Spectrometer at the Beijing Electron-PositronCollider. Approximately 5 pb-' of data, distributed over 12 ecan points, have been collected. A previous maee value for the 7 lepton, obtained using only the ep final state, has been published. In this paper, the final BES result on the maes measurement is presented. The analysis is based on the combined data from the ee, ep, eh, VW, ph, and hh final states, where h denotes a charged ?( or K. A maximum likelihood fit to the r pair production cross section data yields the value rn, = 1776.96+~:~~!~:~~ MeV. PACS number(s): 14.60.Fg, 13.1O.+q
The synthesis and characterization of new selenium coronands and of copper(I) and copper(II) complexes of selenium coronands are reported. Molecular structures in the solid state have been determined by X-ray crystallography. The molecular structures of 6,7,13,14-dibenzo-1,5,8,12-tetraselenacyclotetradecane (dibenzo-14Se4 (1)) and 1,5,9-triselenacyclododecane (12Se3 (2)) adopt conformations which maximize the number of possible gauche C−Se−C−C bond torsion angles. 1: T = 190 K; orthorhombic, space group Pca21; fw = 552.19; Z = 4; a = 9.645(3) Å; b = 12.679(6) Å; c = 15.332(4) Å; V = 1874.9 Å3; R F = 0.027 for 1732 data (I o ≥ 2.5σ(I o)) and 200 variables. 2: T = 190 K; orthorhombic, space group Pn21 a; fw = 363.12; Z = 4; a = 14.943(4) Å; b = 5.638(2) Å; c = 14.229(3) Å; V = 1198.8 Å3; R F = 0.026 for 862 data (I o ≥ 2.5σ(I o)) and 111 variables. The molecular structures of 1,5-diselena-9,13-dithiacyclohexadecane (16Se2S2 (3)) and [Cu(16Se2S2)][SO3CF3]2 (4) correspond to those displayed by both of the analogous tetrathia and tetraselena macrocycles. Compound 3 adopts a [3535] quadrangular conformation. Compound 4, [Cu(16Se4(OH)2][SO3CF3]2 (5) (where 16Se4(OH)2 = cis-1,5,9,13-tetraselenacyclohexadecane-3,11-diol), and [Cu(8Se2(OH))2][SO3CF3]2 (6) (where 8Se2(OH) = 1,5-diselenacyclooctan-3-ol) have typical tetragonally distorted octahedral coordination environments of Cu(II). Compounds 4 and 5 both display a c,t,c configuration of the coronand. Compound 5 has only one hydroxyl group coordinated in an axial position, which requires that the corresponding Se−Cu−Se−C−C−C ring be locked into a boat rather than a chair conformation. The hydroxyl groups in 6 occupy the axial coordination positions. 3: T = 200 K; monoclinic, space group C2/c; fw = 390.36; Z = 12; a = 24.202(9) Å; b = 18.005(7) Å; c = 16.235(5) Å; β = 138.23(3)°; V = 4713 Å3; R F = 0.052 for 1881 data (I o ≥ 2.5σ(I o)) and 172 variables. 4: T = 297 K; monoclinic, space group P21/n; fw = 752.03; Z = 2; a = 8.882(2) Å; b = 10.874(2) Å; c = 13.360(2) Å; β = 97.95(2)°; V = 1277.9 Å3; R F = 0.028 for 1610 data (I o ≥ 2.5σ(I o)) and 176 variables. 5: T = 190 K; monoclinic, space group P21/n; fw = 877.84; Z = 4; a = 8.412(5) Å; b = 20.924(5) Å; c = 15.021(5) Å; β = 100.82(4)°; V = 2597 Å3; R F = 0.059 for 2152 data (I o ≥ 2.5σ(I o)) and 185 variables. 6: T = 195 K; monoclinic, space group P21/c; fw = 877.84; Z = 2; a = 6.875(2) Å; b = 10.945(2) Å; c = 17.496(2) Å; β = 96.76(2)°; V = 1307.3 Å3; R F = 0.023 for 1816 data (I o ≥ 2.5σ(I o)) and 159 variables. [Cu(16Se2S2)][SO3CF3] (7) and [Cu(16Se4(OH))][SO3CF3] (8) (where 16Se4(OH) = 1,5,9,13-tetraselenacyclohexadecan-3-ol) are both tetrahedral Cu(I) coronand complexes with typical t,t,t configurations. 7: T = 205 K; triclinic, space group P1̄; fw = 602.97; Z = 2; a = 10.512(3) Å; b = 10.674(2) Å; c = 10.682(3) Å; α = 101.47(2)°; β = 116.82(2)°; γ = 93.59(2)°; V = 1032.3 Å3; R F = 0.029 for 2237 data (I o ≥ 2.5σ(I o)) and 264 variables. 8: T = 297 K; monoclinic, space group P21/n; fw = 712.77; ...
The microstructures of hydrogenated microcrystalline silicon (μc-Si:H) thin fil ms, prepared by plasma-enhanced chemical vapor deposition (PECVD), hot wire CVD( HWCVD) and plasma assisted HWCVD (PE-HWCVD), have been analyzed by the small ang le x_ray scattering(SAXS) measurement. The SAXS data show that the microstructur es of the μc-Si:H films display different characteristics for different deposit ion techniques. For films deposited by PECVD, the volume fraction of micro-voids and mean size are smaller than those in HWCVD sample. Aided by suitable ion-bom bardment, PE-HWCVD samples show a more compact structure than the HWCVD sample. The microstructure parameters of the μc-Si:H thin films deposited by two-steps HWCVD and PE-HWCVD with Ar ions are evidently improved. The result of 45° tilti ng SAXS measurement indicates that the distribution of micro-voids in the film i s anisotropic. The Fouriertransform infrared spectra confirm the SAXS data.
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