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131.
Gosselin JL Minitti MP Rudakov FM Sølling TI Weber PM 《The journal of physical chemistry. A》2006,110(12):4251-4255
The energy flow and fragmentation dynamics of N,N-dimethylisopropylamine (DMIPA) upon excitation to the 3p Rydberg states has been investigated with use of time-resolved photoelectron and mass spectrometry. The 3p states are short-lived, with a lifetime of 701 +/- 45 fs. From the time dependence of the photoelectron spectra, we infer that the primary reaction channel leads to the 3s level, which itself decays to the ground state with a decay time of 87.9 +/- 10.2 ps. The mass spectrum reveals fragmentation with cleavage at the alpha C-C bond, indicating that the energy deposited in vibrations during the internal conversion from 3p to 3s exceeds the bond energy. A thorough examination of the binding energies and temporal dynamics of the Rydberg states, as well as a comparison to the related fragmentation of N,N-dimethyl-2-butanamine (DM2BA), suggests that the fragments are formed on the ion surfaces, i.e., after ionization and on a time scale much slower than the fluorescence decay from 3s to the ground state. 相似文献
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135.
T. N. Rudakov P. A. Hayes V. T. Mikhaltsevitch W. P. Chisholm 《Applied magnetic resonance》2004,25(3-4):501-512
A study of multipulse sequences that can be used for the detection of HMX (N4(CH2)4(NO2)4) has been undertaken. On the basis of this study, a general method for experimentally optimizing multipulse sequences for the efficient detection of substances is proposed. The relaxation parameters and signal intensities for the nitrogen-14 spectral lines of a polycrystalline HMX sample were measured and the lines that are the most important for practical purposes were chosen. 相似文献
136.
V. T. Mikhaltsevitch T. N. Rudakov J. H. Flexman P. A. Hayes W. P. Chisholm 《Applied magnetic resonance》2004,25(3-4):449-465
A number of methods for cancelling magnetoacoustic and piezoelectric ringing signals in the spectroscopy of the nuclear quadrupole resonance are presented. The suggested methods include using the sequence (?0)?-(τ-?x-2τ-? y -2τ-??x -2τ-??y -τ) n and a multipulse analog of the two-pulse Hahn sequence with the first pulse replaced by a short steady-state sequence. Another method presented is the method of orthogonal effective fields for a fast saturation of the quadrupole spin system which can be used for subtracting the magnetoacoustic and piezoelectric components from the signal. The suggested methods can be used for the practical purposes of detecting explosive substances and narcotics. 相似文献
137.
It is shown how one can transform scalar first-order ordinarydifferential equations which admit non-local symmetries of theexponential type to integrable equations admitting canonicalexponential non-local symmetries. As examples we invoke theAbel equation of the second kind, the Riccati equation and naturalgeneralizations of these. Moreover, our method describes howa double reduction of order for a second-order ordinary differentialequation which admits a two-dimensional Lie algebra of generatorsof point symmetries can be affected if the second-order equationis first reduced in order once by a symmetry which does notspan an ideal of the two-dimensional Lie algebra. 相似文献
138.
O. G. Shakirova V. A. Daletskii L. G. Lavrenova V. A. Varnek D. A. Rudakov V. I. Potkin 《Journal of Structural Chemistry》2014,55(1):45-52
Synthesis procedures for coordination compounds of iron(II) 1,5,6,10-tetra(R)-7,8-dicarba-nido-undecaborates(-1) (carboranes) with tris(pyrazol-1-yl)methane (HC(pz)3) of the composition [Fe{HC(pz)3}2]A2·nH2O (A = (7,8-C2B9H12)? (I), (1,5,6,10-Br4-7,8-C2B9H8)? (II), (1,5,6,10-I4-7,8-C2B9H8)? (III), n = 0–2) are developed. The compounds are studied by static magnetic susceptibility in the temperature range of 160–500 K, electron (diffuse reflectance spectra), IR, and Mössbauer spectroscopy methods. It is shown that the complexes have high-temperature spin-crossover 1 A 1 ? 5 T 2. Transition temperatures (T c) for I–III are 370 K, 380 K, and 400 K respectively. Spin-crossover is accompanied by thermochromism (color change: pink ? white). 相似文献
139.
A. M. Rudakov V. V. Sergievskii T. V. Zhukova 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2014,88(6):903-907
A modified Robinson-Stokes equation with terms that consider the formation of ionic hydrates and associates is used to describe thermodynamic properties of aqueous solutions of electrolytes. The model is used to describe data on the osmotic coefficients of aqueous solutions of alkali metal carboxylates, and to calculate the mean ionic activity coefficients of salts and excess Gibbs energies. The key contributions from ionic hydration and association to the nonideality of solutions is determined by analyzing the contributions of various factors. Relations that connect the hydration numbers of electrolytes with the parameters of the Pitzer-Mayorga equation and a modified Hückel equation are developed. 相似文献
140.
E. S. Rudakov V. P. Tret’yakov V. L. Lobachev L. A. Min’ko Ya. V. Matvienko V. G. Popov 《Theoretical and Experimental Chemistry》2006,42(5):303-307
The relative rate constants (krel) were measured for the oxidation of alkanes (RH) by peroxynitrous acid (HOONO) in aqueous solutions at 25 °C. The krel values
for the reactions of RH with HOONO and with OH radicals in the series of C2-C7 alkanes and the isotopic effects (c-C6H12/c-C6D12) agree. However, the krel value for methane was lower than for its reaction with OH. Possible reaction mechanisms are discussed.
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Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 5, pp. 295–299, September–October, 2006. 相似文献