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901.
902.
Cure Degree Estimation of Photocurable Coatings by DSC and Differential Photocalorimetry 总被引:1,自引:0,他引:1
Ruiz C. S. B. Machado L. D. B. Vanin J. A. Volponi J. E. 《Journal of Thermal Analysis and Calorimetry》2002,67(2):335-341
Radiation-curable coatings have acquired importance, because they are environmentally-friendly (no solvent emission)and require
low energy for curing, when compared to other conventional heat-curable products. UV-curable coatings performance depends
on the cure quality. Suitable methods were evaluated to estimate the degree of cure applying quantitative techniques, such
as differential scanning calorimetry (DSC) and differential photocalorimetry (DPC), in order to determine the residual heat
of curing in UV-cured films. The results of the DPC technique showed better sensibility than DSC technique, although the use
of suitable pans for the case of clear coats must be considered.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
903.
The kinetics of oxidation of the chromium(III)‐guanosine 5‐monophosphate complex, [CrIII(L)(H2O)4]3+(L = guanosine 5‐monophosphate) by periodate in aqueous solution to CrVI have been studied spectrophotometrically over the 25–45 °C range. The reaction is first order with respect to both [IO4?] and [CrIII], and increases with pH over the 2.38–3.68 range. Thermodynamic activation parameters have been calculated. It is proposed that electron transfer proceeds through an inner‐sphere mechanism via coordination of IO4? to chromium(III). 相似文献
904.
Fukuda T Makarova EA Luk'yanets EA Kobayashi N 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(1):117-133
Benzene- or 2,3-naphthalene-ring-expanded tetraazachlorins (TACs), tetraazabacteriochlorins (TABCs), and tetraazaisobacteriochlorins (TAiBCs) have been synthesized by using tetramethylsuccinonitrile as a source of hydrogenated sites. The derived compounds were characterized by using NMR spectroscopy, X-ray crystallography, electronic and magnetic circular dichroism (MCD) spectroscopy, and electrochemical and spectroelectrochemical methods. X-ray analysis revealed that the benzene-fused TAiBC deviates slightly from planarity at the hydrogenated sites as a result of the presence of sp(3) carbons, which prefer a nonplanar tetrahedral conformation. The spectral data were analyzed by using a band deconvolution technique. In the electronic absorption spectra of TAC and TABC species, the Q band splits into two intense components and smaller splittings were observed for the 2,3-naphthalene-fused derivatives relative to the benzo-fused species. In contrast, in the case of TAiBCs, the Q band splitting was apparently not observed in absorption spectra, as expected from the C(2v) molecular symmetry. However, MCD signals of the Q band in TAiBCs showed Faraday B terms, implying that the accidental degeneracy of the LUMO and LUMO+1 was broken even for adjacently ring-fused species. Relative molecular orbital energies were estimated by using cyclic and differential pulse voltammetry. The first reduction potentials were close for TACs and TABCs, although those of TAiBCs shifted to more negative potentials. In contrast, although TABCs and TAiBCs exhibited similar first oxidation potentials, those of TACs appeared at more positive potentials. These properties were reproduced and rationalized by molecular orbital and configuration interaction calculations within the framework of the ZINDO/S Hamiltonian. DFT-level frequency calculations have succeeded in reproducing the IR spectra for low-symmetry tetraazaporphyrin (TAP) derivatives for the first time. The relationship between structures and spectral features is discussed. 相似文献
905.
荧光分光光度计的功能开发 总被引:2,自引:0,他引:2
固、液体吸收光谱测量的附件是由光阑、负透镜、全反射棱镜,吸收不也组成的光学系统,将它配置到进口荧光分光光度计上,可以扩展其功能,使其具有紫外分光光度计(UV)的功能,能够测量固体、液体样品的透射光谱和吸收光谱。 相似文献
906.
907.
Céline Chizallet Guylène Costentin Jean-Marc Krafft Hélène Lauron-Pernot Michel Che 《Chemphyschem》2006,7(4):904-911
Photoluminescence decay studies of emitting species on MgO nanocubes at room temperature provide evidence of three surface species characterized by an excitation and emission wavelength couple {lambda(exc);lambda(em)}. Species A corresponds to {lambda(exc)=240 nm; lambda(em)=380 nm}, whereas the couple {lambda(exc)=280 nm; lambda(em)=470 nm} is assigned to two species: B and B', the former is involved in energy transfer from excited state A* and the latter in direct emission from excited state B'*. A simple model for energy transfer from species A* to B is proposed. The numerical resolution of equations corresponding to this model is in good agreement with experimental data. This method quantifies the kinetics of intrinsic emission and energy transfer processes. Lifetime values indicate that phosphorescence is taking place, and species A, B and B' are identified as edge O(2-) (4 C), corner O(2-) (3 C) and kink O(2-) (3 C) oxide ions respectively. 相似文献
908.
I. L. Eremenko M. A. Golubnichaya S. E. Nefedov A. A. Sidorov I. F. Golovaneva V. I. Burkov O. G. Ellert V. M. Novotortsev L. T. Ermenko A. Sousa M. R. Bermejo 《Russian Chemical Bulletin》1998,47(4):704-718
The reaction of NiCl2·6H2O with Me3CCOOH and KOH taken in a molar ratio of 1:2:2 in water afforded the nonanuclear antiferromagnetic complex Py2Ni2(Me3CCOOH)2(OOCCMe3)2(μ-OOCCMe3)2(μ-OH2), which apparently contains NiII and NiIII atoms. The complex was isolated by extraction with CH2Cl2, benzene, or hexane. The reactions of this complex with pyridine bases (pyridine (Py), 3,4-lutidine (Lut), and nicorandil
(Nic)) gave the adducts L4Ni2(OOCCMe3)2(μ-OOCCMe3)2(μ-OH) (L=Py, Lut, or Nic, respectively). According to magnetic measurements, intramolecular ferromagnetic exchange interactions
in these adducts are complemented by intermolecular antiferromagnetic interactions. Pyrolysis of the pyridine adduct in air
or under an inert atmosphere in xylene yielded the antiferromagnetic complex Py2Ni2(Me3CCOOH)2(OOCCMe3)2(μ-OOCCMe3)2(μ-OH2), which contains NiII atoms. The structures of all the complexes synthesized were established by X-ray diffraction analysis. The electronic absorption
spectra of these compounds are considered.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 725–738, April, 1998. 相似文献
909.
910.
利用四(3'-碘丙硫基)四硫富瓦烯和四硫富瓦烯二钠盐反应合成新的三(四硫富瓦烯)环蕃, 并通过循环伏安法和化学氧化法分别对其氧化还原性质和紫外光谱进行了研究. 相似文献