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1.
T. Brian Cavitt Brian Phillips Charles E. Hoyle Bo Pan Sukhendu B. Hait Kalyanaraman Viswanathan Sonny Jnsson 《Journal of polymer science. Part A, Polymer chemistry》2004,42(16):4009-4015
Three‐component photoinitiators comprised of an N‐arylphthalimide, a diarylketone, and a tertiary amine were investigated for their initiation efficiency of acrylate polymerization. The use of an electron‐deficient N‐arylphthalimide resulted in a greater acrylate polymerization rate than an electron‐rich N‐arylphthalimide. Triplet energies of each N‐arylphthalimide, determined from their phosphorescence spectra, and the respective rate constants for triplet quenching by the N‐arylphthalimide derivatives (acquired via laser flash photolysis) indicated that an electron–proton transfer from an intermediate radical species to the N‐arylphthalimide (not energy transfer from triplet sensitization) is responsible for generating the initiating radicals under the conditions and species concentrations used for polymerization. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4009–4015, 2004 相似文献
2.
J. Tellinghuisen P. Berwanger J.G. Ashmore K.S. Viswanathan 《Chemical physics letters》1981,84(3):528-533
We have observed and identified positive ions produced in a spark discharge in SF6 at high pressure. The ion species were found to be very sensitive to impurities. In purified SF6 the ions were sulfur-rich and complex before reacting to form chemically stable long-lived products. 相似文献
3.
Balawant S. Joshi Narayanan Viswanathan Dilip H. Gawad Venkatachalam Balakrishnan Wolfgang von Philipsborn 《Helvetica chimica acta》1975,58(8):2295-2305
Three new alkaloids designated as cyclostachine A (2), cyclostachine B (7) and cyclopiperstachine (10) have been isolated from Piper trichostachyon C. DC. Their structures have been derived on the basis of spectral and degradative studies and confirmed by synthesis. The 1H- and 13C-NMR. spectra of these compounds are discussed. 相似文献
4.
We discuss different compactifications of the spacial part 3 of Minkowski space and give classifications of the vacuum structure for a Yang-Mills theory.Partially supported by DFG and by Simon Fraser UniversityPartially supported by National Research Council of Canada grant 751-010 相似文献
5.
The anomalies of the second and third-order elastic constants have been considered for the phase transition of strontium titanate
within the framework of Landau’s theory. All the anomalies of the second-order elastic constants have been obtained in a single
formula using Kronecker delta functions and relations among them have been established. The real parts ofC*11 andC*44 decrease steeply across the transition temperature and thereafter flatly tend to their asymptotic values in the low temperature
phase agreeing qualitatively with experimental observations. We have also derived expressions for the third-order elastic
anomalies and discussed the temperature variation of the real part ofC*111. We have derived expressions for the attenuation of the longitudinal and transverse waves along certain simple symmetry directions
and have shown that there is nearly good agreement with experimental observations. 相似文献
6.
An emission system of I2 in Ar in the region 2830–2890 Å is examined under high resolution and found to display fine violet-degraded band structure. This system is interpreted as a charge-transfer transition originating from an ion-pair state near 47 000 cm?1 and terminating on a weakly bound state which dissociates to two ground-state atoms. This interpretation is supported by spectral simulations employing a bound-free model. The transition is tentatively assigned as , according to which the excited state becomes the fourth ion-pair state near 47 000 cm?1 to be experimentally characterized, and the lower state is the last component of the lowest 3Π state to be identified. The vibrational assignments include about 45 bands in 127I2 and 129I2, spanning v′ = 0–4 and v″ = 6–19, but with the numbering of the lower state remaining uncertain by several units. The main spectroscopic constants for the excited state are Te = 47 070 cm?1, ?e = 105.7 cm?1, ?exe = 0.49 cm?1. The spectral simulations place the lower state's potential curve 34 650 cm?1 below the upper state at R = R′e, with slope ?850 cm?1/Å. For our “best” numbering of the lower state, ?e = 20.5 cm?1, ?exe = 0.29 cm?1, Te = 12 190 cm?1, and De = 360 cm?1. 相似文献
7.
A theory has been given for the scattering of neutrons by anharmonic crystals, for which terms of the typeV
(3) (k
1j1; —k
1j1;o
j) which contribute to the sublattice displacements are not neglected. Using the standard perturbation theory in the interaction
picture or Green’s function method, an expression has been derived for the differential scattering cross-section which brings
in the shift and the width of the phonons in one-phonon energy exchange processes. It is shown that the sublattice displacements
will modify the phase factor arising from the scattering by any atom in the unit cell, and the Debye-Waller factor also gets
altered both by the sublattice displacements as well as by higher order terms arising from anharmonicity. It is shown that
the differential scattering cross-section contains a term linearly depending on the third order anharmonicity coefficientV
(3) (k
1j1;k
2j2;k
3j3) and neutron scattering by crystals should provide a useful method for evaluating the third order anharmonicity coefficients. 相似文献
8.
We report an accurate method to measure the group-velocity dispersion (GVD) of transparent materials by use of spectrally resolved phase-shifting interferometry. The GVD of silica glass slide measured using an eight-step phase-shifting algorithm agrees well with that calculated using the Sellmeier dispersion equation over the entire visible wavelength region, with a rms error of < or =0.0036 microm(-2), better than that of other measurement methods reported so far. 相似文献
9.
181Ta time differential perturbed angular correlation (TDPAC) and positron lifetime measurements were carried out on homogeneously
α-implanted CuHf samples. TDPAC measurements indicate the trapping of vacancy clusters and helium associated defect complexes
by Hf atoms. The presence of helium-vacancy complexes and helium stabilised voids has been identified by positron lifetime
measurements. Further the nucleation and growth stages of helium bubbles have been identified. TDPAC and positron lifetime
measurements indicate that Hf atoms act as heterogeneous nucleating centers for helium bubbles. Hf atoms are found to suppress
the bubble growth in CuHf as indicated by the results of positron lifetime measurements. 相似文献
10.
S. Gopal C. Viswanathan M. Thamilselvan K. Premnazeer Sa. K. Narayandass D. Mangalaraj 《Ionics》2004,10(3-4):300-303
Indium Selenide thin films were electrodeposited on Indium Tin Oxide (ITO) coated glass substrates from a mixture of Indium
trichloride (InCl3) and selenium dioxide (SeO2) in aqueous solution by the potentiostatic electrodeposition technique. The InSe films showed that Mott’s variable-range
hopping conductivity (VRH) is dominant under low field (∼2×105 Vcm−1) condition. At high field the Current-Voltage studies (in the temperature range 300 – 380 K) revealed that the conductivity
of Indium selenide thin films is of Poole-Frenkel type. The plot drawn between Ln (I/V) and tV showed a straight line and
also the experimental data and the theoretical data closely matches. Hence Poole-Frenkel mechanism is confirmed and discussed
in detail.
Paper presented at the 2nd International Conference on Ionic Devices, Anna University, Chennai, India, Nov. 28–30, 2003. 相似文献