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921.
Vibrational analyses, of the electronic bands of 1-hydroxynaphthalene and 2-hydroxynaphthalene corresponding to the 312 nm
electronic transition in naphthalene, have been carried out from the vapour phase absorption spectra recorded under high resolution.
It is found that the prominent vibronic bands owe their large intensities to a different vibronic interaction than that in
naphthalene.
On leave from Pt. Jawaharlal Nehru College, Banda 210 001, India. 相似文献
922.
Yb(Ⅲ)、Gd(Ⅲ)与EHPG配合物的光谱研究 总被引:7,自引:0,他引:7
在0.01mol·L-1 N-2-羟乙基哌嗪-N′-2-乙磺酸(Hepes),pH 7.4和室温条件下,应用荧光光谱和紫外差光谱研究了Yb(Ⅲ),Gd(Ⅲ)与N-N′-乙烯-二[2-(2-羟基苯基)甘氨酸](EHPG)的配合反应。结果表明,随着稀土离子Yb(Ⅲ)或Gd(Ⅲ)的不断滴加,EHPG在310nm处的最大荧光峰强度逐渐降低,而其紫外差光谱在238和292nm处的吸收峰逐渐增强,当稀土离子Yb(Ⅲ)或Gd(Ⅲ)达到一定量时,310nm处的荧光强度、238和292nm处的吸收峰强 相似文献
923.
The efficiency of oxidation in wet decomposition procedures for organic materials can be of great importance to the quality of the analytical data from various measurement techniques. A novel, microwave-assisted, high-temperature/high-pressure UV-TiO2 digestion procedure was developed for the accelerated decomposition of various biological samples. The technique is based on a closed, pressurized, microwave digestion apparatus (MW). UV irradiation is generated by immersed electrodeless Cd discharge lamp operated by the focused microwave field in the single polymer vessel. To enhance oxidation efficiency, a photocatalyst TiO2 was added to the microwave heated Teflon bomb. Measures of digestion completeness were provided by the appearance of carbon content and determination of trace and minor elements, enabling a comparison of different digestion procedures and sample types. Compared with other digestion systems, unusually low residual carbon contents were obtained. For the organic compounds and biological samples digested, the residual carbon content was 1-2%, corresponding to a decomposition efficiency of 98-99%. The potential of the MW-UV-TiO2 system was illustrated by the decomposition of four certified reference materials (serum, urine, milk, arsenobetaine solution) and subsequent determination of trace and minor elements. Recoveries between 92% and 107% were found. 相似文献
924.
Ph. Marechal R. Legras J. M. Dekoninck 《Journal of polymer science. Part A, Polymer chemistry》1993,31(8):2057-2067
Polyamide samples were heated under vacuum or mixed in a Brabender plastograph. UV absorbance, chain end concentration, and molecular weight were studied. Postcondensation was observed for polyamide heated under vacuum. For polyamide samples mixed in the plastograph, atmosphere, shear rate, and temperature changed. Melt viscosity and intrinsic viscosity are in good correlation in a log-log plot. Oxidation effect on molecular weight and amine chain end concentration could be well related to UV absorbance. The oxygen diffusion into the molten polyamide is a critical parameter. The oxygen concentration in the polyamide mixed under air is ca. 20 times higher than when mixed under nitrogen. The introduction of preoxidized material in the molten polyamide or mixing in the presence of oxygen have similar effects. Postcondensation and oxidation strongly influence the melt behavior of polyamides. © 1993 John Wiley & Sons, Inc. 相似文献
925.
U-Chan Chung José L. Pizarro Luis Lezama Teófilo Rojo 《Journal of solid state chemistry》2005,178(9):2913-2921
A new manganese (II) phosphite with the formula Mn(HPO3) has been synthesised under mild hydrothermal conditions and autogenous pressure. Large pink coloured single crystals were obtained, allowing the resolution of the structure by x-ray diffraction. Mn(HPO3) crystallises in the P21/c monoclinic space group with a=8.036(3) Å, b=8.240(3) Å, c=10.410(3) Å, β=124.73(3)° and Z=8. The structure consists of a three-dimensional, compact framework of edge sharing MnO6 octahedra linked to phosphite groups via oxygens. The presence of the phosphite anion has been confirmed by IR spectroscopy. Mn(HPO3) presents a high thermal stability limit of 580 °C, before rapid transformation to Mn2P2O7 occurs. Photoluminescence and diffuse reflectance spectroscopy studies show the presence of high spin Mn(II) in significantly distorted octahedral coordination with Dq and Racah parameters of Dq=820, B=910 and C=3135 cm−1. The ESR spectra, performed at different temperatures, are isotropic with a g-value of 2.00(1). Magnetic measurements indicate global antiferromagnetic interactions with a ferromagnetic transition at 15 K, attributed to a canting of the antiferromagneticaly aligned spins. 相似文献
926.
本文以含有端基炔的芳硫醚为原料,碘苯二乙酯为氧化剂,氯化亚铜为催化剂,室温下反应30 min,合成了1,4-二(2-芳硫基苯基)-1,3-丁二炔化合物。通过1HNMR、13CNMR等对其进行了结构表征,并研究了其光学性质,以及作为紫外线吸收剂在紫外光固化涂料中的应用。结果表明:该类化合物能够有效吸收270~360 nm的紫外光,且光降解程度小,并具有与树脂、单体相容性好、无气味等特点。同时,合成的目标化合物在光固化过程中不参与自由基体系的固化,且增强了涂料及固化涂层的光稳定性,有益于紫外光固化涂料的存储,是一类具有发展前景的紫外光吸收剂。 相似文献
927.
Maria G.M. Purwanto 《Tetrahedron letters》2006,47(23):3849-3852
An urocanamide nucleoside designed and previously tested as its protected ribose derivative in aprotic solvents for binding a cytosine-guanine (CG) Watson-Crick base pair was successfully incorporated into a triplex forming oligonucleotide. Binding affinity and specificity of this nonnatural nucleoside were studied in a triple helix with duplex targets containing all four possible Watson-Crick base pairs opposite the nucleoside analog in the third strand. UV melting experiments indicate the formation of a well-defined triplex with specific binding of the urocanamide analog to a CG inversion of the homopurine-homopyrimidine target. However, binding affinities in the triplex are weak and much lower when compared to the canonical base triads. 相似文献
928.
均一形貌的ZnO纳米棒的制备及其光催化性能研究 总被引:20,自引:0,他引:20
ZnO nanorods were synthesized from high purity Zn granule by a vapor phase deposition in the Ar + O2 gas. The products were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The ZnO nanorods were typically 1~2 μm in length and 20~30 nm in diameter with an aspect ratio as high as 20. The UV absorption properties were detected and the results show that the ZnO nanorods have an extremely strong absorption at 200~380 nm wavelength. The results were good when the ZnO nanorods were used as photocatalyst. 相似文献
929.
S. P. Babailov L. S. Klimenko I. Ya. Mainagashev 《Journal of Structural Chemistry》2006,47(4):663-667
It has been stated by 1H NMR and UV spectrophotometry that 1-(4-tert-butil-phenoxy)-2-cetylamino-9,10-anthraquinone photoisomerizes to 9-(4-tert-butylphenoxy)-2-cetylamino-1,10-anthraquinon with quantum yield ? = 0.4 ±0.1 under light excitation in the absorption band region in the UV/visible spectrum range with the maximum λ = 441 nm. 相似文献
930.
不同质量Cn笼电子结构和UV谱的理论研究 总被引:1,自引:0,他引:1
用INDO/2和INDO/CI方法研究了C_(24)、C_(50)、C_(60)和C_70的电子结构和UV谱。稳定性的顺序为C_(60)~C_(70)>C_(50)>>C_(24)。以C_(60)为中心向两边的C_n原子簇,其UV谱发生红移。 相似文献