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81.
D.A. Akimov A.A. Ivanov M.V. Alfimov S.N. Bagayev T.A. Birks W.J. Wadsworth P.St.J. Russell A.B. Fedotov V.S. Pivtsov A.A. Podshivalov A.M. Zheltikov 《Applied physics. B, Lasers and optics》2002,74(4-5):307-311
Spectral broadening of femtosecond Cr:forsterite laser pulses is enhanced due to the use of tapered fibers. Supercontinuum
generation with unamplified subnanojoule femtosecond Cr:forsterite laser pulses is observed for the first time. With 40-fs
0.6-nJ pulses of 1.25-μm Cr:forsterite laser radiation coupled into a tapered fiber having a taper waist diameter of about
2 μm and a taper waist length of 90 mm, we observed the spectra spanning more than two octaves at the output of the fiber
in the regime of anomalous group-velocity dispersion. This result opens the way for the creation of compact femtosecond Cr:forsterite
laser plus tapered fiber systems for optical metrology and biomedical applications.
Received: 23 October 2001 / Accepted: 16 January 2002 / Published online: 14 March 2002 相似文献
82.
83.
L. G. Kuz’mina A. V. Churakov J. A. K. Howard A. I. Vedernikov N. A. Lobova A. A. Botsmanova M. V. Alfimov S. P. Gromov 《Crystallography Reports》2005,50(2):234-253
The crystal and molecular structures of six perchlorates (viologen analogues) are studied. These compounds serve as models of the acceptor component of new charge-transfer complexes containing bis(18-crown-6)stilbene as the donor. The polycyclic aromatic system of divalent cations is demonstrated to be virtually planar. In all cations, the side chains at the nitrogen atoms are oriented in opposite directions almost perpendicular to the plane of the cyclic system. This orientation of the spacers of these carbocations is indicative of their preorganization for the formation of 1: 2 charge-transfer complexes. Analysis of the crystal packings provides evidence that two positive charges on the conjugated systems of the organic cations and the perchlorate anions play a destructive role in the formation of stacking motifs. An increase in the size of the conjugated system and the involvement of an aromatic solvent molecule as an additional building block in a supramolecular system are favorable for the formation of a stacking supramolecular architecture. 相似文献
84.
S. P. Gromov E. N. Ushakov O. A. Fedorova A. V. Buevich M. V. Alfimov 《Russian Chemical Bulletin》1996,45(3):564-572
The stoichiometry of complexation of crown ether styryl dyes with Mg2+, Ca2+, and Ba2+ ions and the dependence of the stability constants of these complexes on the length of theN-sulfoalkyl substituent were investigated. Introduction of a terminal sulfo group into theN-ethyl substituent had but a small effect on the stability constant for the complexes with 1 : I stoichiometry. Increase in the length of theN-substituent by one or two methylene groups resulted in a jumpwise rise of this constant. The effect observed was attributed to the formation of the intramolecular ion pair. The dimerization constant for Mg2+ complexes increased dramatically when passing from the sulfopropylN-substituent to the sulfobutyl one. The increase in the constant results from the decrease in steric strains in the dimeric complex.For Part 16, see Ref. ITranslated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 605–613, March, 1996. 相似文献
85.
S. P. Gromov O. A. Fedorova A. I. Vedernikov Yu. V. Fedorov M. V. Alfimov 《Russian Chemical Bulletin》1997,46(5):959-966
Novel crown-containing styryl dyes (CSD) based on 15-crown-5-substituted benzothiazole with various electron-donating groups
in thepara-position of the benzene ring were synthesized. Spectral and photochemical properties ofcis- andtrans-isomers of CSD and their complexes with Mg2+ ions in solutions were studied. By analysis of spectral parameters and the magnitudes and directions of the shifts of absorption
(fluorescence) maxima, the effects of substituents and complex formation on the photochromism of CSD were elucidated. Using
quantum-chemical calculations, the possibility of controlling the degree of participation of either of the two chromophores
in the long-wave electron transition by complex formation was analyzed.
For Part 19, see Ref. 1.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 999–1006, May, 1997. 相似文献
86.
The microstructure of Langmuir-Blodgett films formed by stearic acid salts was calculated with paired atomic-atomic potentials. The calculations were performed for a monolayer and Y-type bilayer. Quantitative agreement with the experimental data was obtained in using standard values of the atomic parameters borrowed from conformational analysis. It was shown that the packing density in the films investigated is determined by the geometric dimensions of the hydrocarbon tails. In going from a monolayer to a bilayer, the geometric parameters of the two-dimensional crystal lattice remain almost unchanged, but the packing rigidity increases significantly.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2778–2782, December, 1990. 相似文献
87.
S. P. Gromov A. I. Vedernikov E. N. Ushakov M. V. Alfimov 《Russian Chemical Bulletin》2008,57(4):793-801
The results of the comprehensive study of novel supramolecular donor-acceptor complexes of bis(crown)stilbenes and bis(crown)azobenzene
with viologen analogs are generalized. The original methodology for self-assembling of the organic donor-acceptor complexes
possessing a very high thermodynamic stability is described. The hydrogen bonds between the peripheral fragments of the donor
and acceptor play the key role in the self-assembling. The influence of different structural factors on the thermodynamic
stability of the supramolecular donor-acceptor complexes and the efficiency of charge-transfer interactions between the donor
and acceptor are discussed. The driving forces of the reaction leading to exotic trimolecular charge-transfer complexes are
considered.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 779–787, April, 2008. 相似文献
88.
EPR and fluorescence study of molecular dynamics of lipids in bilayers adsorbed on porous silica gel
V. A. Livshits B. B. Meshkov A. V. Koshkin B. G. Dzikovskii M. V. Alfimov 《High Energy Chemistry》2017,51(4):256-262
Lipid bilayers immobilized on highly porous silica gel monoliths (SLBs) have been proposed as templates for chemosensors. Procedures for preparation and characterization of SLBs have been developed and applied. Rotational dynamics and orientational ordering at different depths in a SLB membrane and, for comparison, in bilayer liposomes have been studied for the first time using n-PC phospholipid spin labels. 相似文献
89.
Basilevsky M. V. Nikitina E. A. Grigoriev F. V. Bagaturyants A. A. Alfimov M. V. 《Structural chemistry》2011,22(2):427-432
The electrostatic interaction energy between a charged or polar molecule and a spherical polarizable nanoparticle is studied
within the advanced dielectric continuum model proposed previously. The molecule can be located either inside or outside the
nanoparticle or in the vicinity of its boundary surface. The nanoparticle and its environment are considered as a polarizable
medium and described in terms of a nonuniform dielectric continuum approximation with a position-dependent dielectric permittivity
function e(r) \varepsilon (r) , where r is the position vector. A special construction of this function accounts for the proper treatment of sophisticated boundary
effects. Test computations are performed for a number of sample molecules. 相似文献
90.
A. A. Safonov A. A. Bagaturyants V. A. Sazhnikov M. V. Alfimov 《High Energy Chemistry》2011,45(3):229-236
The interaction of 9-diphenylaminoacridine dye (indicator) with several small analyte molecules (methanol, acetonitrile, acetone,
tetrahydrofuran, benzene, ammonia, formaldehyde, and acetaldehyde) has been theoretically studied in relation to the problem
of the development of optical chemosensors based on organic dyes. The structures of the resulting complexes and the absorption
spectra of 9-diphenylaminoacridine and its complexes with analytes were calculated using density functional theory (DFT) with
the PBE0 functional and the 6-31G(d,p) basis set. It was demonstrated that complexes of two types with different mutual arrangements
of molecules corresponding to the lateral and stacking structures can be formed for each analyte. The calculated absorption
spectrum only weakly changes upon complex formation, which is in agreement with experimental data on the absorption spectra
of 2,7-dimethyl-9-ditolylaminoacridine in solutions of corresponding solvents. The method for the calculation of excited states
that was used in this work can be applied to the calculation of the fluorescence spectra of 9-diphenylaminoacridine complexes. 相似文献