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81.
V. S. Avilkina N. N. Andrianova A. M. Borisov Yu. S. Virgiliev E. S. Mashkova V. I. Shulga 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2012,6(2):212-216
The results of experimental study and computer simulation of SG-P-0.1 carbon-ceramic composite sputtering under 30 keV Ar+ ion irradiation at normal incidence are presented. A comparison with the simulation data shows that taking into account the
nanometric wave-like relief well describes an approximately threefold increase in the sputtering yield observed in the experiment
in comparison to the smooth surface calculation. 相似文献
82.
83.
Zenkevich E Cichos F Shulga A Petrov EP Blaudeck T von Borczyskowski C 《The journal of physical chemistry. B》2005,109(18):8679-8692
The formation of nanoassemblies of CdSe/ZnS quantum dots (QD) and pyridyl-substituted free-base porphyrin (H(2)P) molecules has been spectroscopically identified by static and time-resolved techniques. The formation of nanoassemblies has been engineered by controlling the type and geometry of the H(2)P molecules. Pyridyl functionalization gives rise to a strong complex formation accompanied by QD photoluminescence (PL) quenching. For some of the systems, this quenching is partly related to fluorescence resonance energy transfer (FRET) from the QD to H(2)P and can be explained according to the F?rster model. The quantitative interpretation of PL quenching due to complexation reveals that (i) on average only about (1)/(5) of the H(2)P molecules at a given H(2)P/QD molar ratio are assembled on the QD and (ii) only a limited number of "vacancies" accessible for H(2)P attachment exist on the QD surface. 相似文献
84.
E.I. Zenkevich A.M. Shulga A.V. Chernook G.P. Gurinovich 《Chemical physics letters》1984,109(3):306-311
It has been found experimentally that a whole class of isocycle-containing porphyrins, including synthetic and natural objects and their covalently linked dimers, shows NH-tautomerism which manifests itself in isotropic solutions in normal electronic spectra both at 77 K and higher temperatures (up to 500 K). 相似文献
85.
Shulga Yu. M. Kabachkov E. N. Korepanov V. I. Kichigina G. A. Kushch P. P. Kiryukhin D. P. Dremova N. N. Baskakov S A. Vaish Rahul Kumar Yogesh 《High Energy Chemistry》2021,55(6):488-494
High Energy Chemistry - The process of hydrophobization of melamine sponges has been investigated. Solutions of radiation-synthesized tetrafluoroethylene telomers, which had different chain lengths... 相似文献
86.
Talyzin AV Tsybin YO Purcell JM Schaub TM Shulga YM Noréus D Sato T Dzwilewski A Sundqvist B Marshall AG 《The journal of physical chemistry. A》2006,110(27):8528-8534
Products of the reaction of C(60) with H(2) gas have been monitored by high-resolution atmospheric pressure photoionization Fourier transform ion cyclotron resonance mass spectrometry (APPI FT-ICR MS), X-ray diffraction, and IR spectroscopy as a function of hydrogenation period. Samples were synthesized at 673 K and 120 bar hydrogen pressure for hydrogenation periods between 300 and 5000 min, resulting in the formation of hydrofullerene mixtures with hydrogen content ranging from 1.6 to 5.3 wt %. Highly reduced C(60)H(x) (x > 36-40) and products of their fragmentation were identified in these samples by APPI FT-ICR MS. A sharp change in structure was observed for samples with at least 5.0 wt % of hydrogen. Low-mass (300-500 Da) hydrogenation products not observed by prior field desorption (FD) FT-ICR MS were detected by APPI FT-ICR MS and their elemental compositions obtained for the first time. Synthetic and analytical fragmentation pathways are discussed. 相似文献
87.
Aldosh S. M. Sanina N. A. Rakova O. A. Shilov G. V. Kulikov A. V. Shulga Yu. M. Ovanesyan N. S. 《Russian Chemical Bulletin》2003,52(8):1702-1708
Neutral paramagnetic binuclear iron nitrosyl complexes, whose structures and properties differ from those of the known Roussin"s red salt esters, were synthesized for the first time. The iron nitrosyl complexes [Fe2(2-SR)2(NO)4]·nH2O (1-S, 1-N; n = 1 or 2; R is 5-amino-1,2,4-triazol-3-yl (1), 1,2,4-triazol-3-yl (2), 1-methyltetrazol-5-yl (3), or benzothiazol-2-yl (4)) were prepared by the exchange reactions of Na2Fe2(S2O3)2(NO)4 with heterocyclic thiols. According to the results of X-ray diffraction analysis, complex 1 has a centrosymmetrical dimeric structure in which the iron atoms are linked through the -N—C—S structural fragment. Each Fe atom is bound to the N atom of one ligand and the S atom of another ligand. The isomer shifts of complexes 1—4 have virtually equal values (Fe = 0.291(1)—0.304(1) mm s–1 at T = 85 K), which are twice as large as Fe for Roussin"s red salt esters. The iron atoms in complexes 1—4 have the low-spin configuration d7 (Fe+). The ESR spectra of polycrystalline powders of complexes 1—4 consist of a single Lorentzian line with g = 2.032 and a width of 6—10 mT. The temperature dependence of the magnetic susceptibility of complex 1 in the temperature range of 80—300 K is adequately described by the Curie—Weiss law with 8 K; the effective magnetic moment per iron atom is 1.85 B. 相似文献
88.
Shulga A Widmaier J Pefferkorn E Champ S Auweter H 《Journal of colloid and interface science》2003,258(2):228-234
Adsorption from electrolyte solutions of fully hydrolyzed polyvinylamine on cellulose fibers was investigated by supplying the polymer to the fibers at controlled rate. This was implemented by employing a reactor only open to the fluid in which the fiber dispersion were confined and homogenized. The adsorbed layers may be defined as diffuse or dense layers. Diffuse layers are characterized by a surface coverage limited to 0.65 mg/g cellulose in salt-free solutions. Addition of NaCl or CaCl(2) to the fiber dispersion and the polymer solution promotes the adsorption rate and increases the amount of adsorption to 1.5 mg/g cellulose. For dense polymer layers, for which the coverage amounts to values close to 10 mg/g cellulose in salt-free systems, addition of electrolyte does not change the kinetic and adsorption characteristics. Insofar as the variation of the molecular areas of the polymer within the diffuse layers as a function of the ionic strength parallels the variation of the molecular characteristics of solute molecules, the formation of diffuse layers is expected to proceed by random deposition of solute molecules which later individually sustain strong reconformation. Adsorption isotherms show a limited influence of the ionic strength. Obviously, the passage from dense layers of high surface coverage to low adsorption values at equilibrium requires extended reconformation of adsorbed macromolecules and desorption of a great part of the molecules already adsorbed. 相似文献
89.
V.N.?VasiletsEmail author A.?Hirose Q.?Yang A.?Singh R.?Sammynaiken M.?Foursa Y.M.?Shulga 《Applied Physics A: Materials Science & Processing》2004,79(8):2079-2084
Diamond-like carbon (DLC) films doped with nitrogen and oxygen were deposited on silicon(100) and polytetrafluoroethylene (PTFE) substrates by hot wire plasma sputtering of graphite. The morphology and chemical composition of deposited films has been characterized by scanning electron microscopy, XPS, Auger, FTIR spectroscopy and micro-Raman scattering. Plasmon loss structure accompanying the XPS C 1s peak and electron energy loss spectroscopy (EELS) in reflection mode was used to study the fraction of sp3 bonded C atoms and the density of valence electrons. Raman spectra show two basic C–C bands around 1575 cm-1 (G line) and 1360 cm-1 (D line) . Auger depth profiling spectroscopy was used to measure the spatial distributions of C, N and O atoms in the surface layer of DLC films. The fraction of sp3 bonded atoms of about 40% was detected in DLC films by XPS plasmon loss and EELS techniques. Nitrile and iso-nitrile groups observed in FTIR spectra demonstrated the existence of sp bonded carbon in doped DLC films. The typical for DLC films specific density 1.7–1.8 g/cm3 was obtained from EELS and XPS data. PACS 52.77.Dq; 81.65.-b; 82.80.Pv 相似文献
90.
E. I. Sagun E. I. Zenkevich V. N. Knyukshto A. M. Shulga 《Optics and Spectroscopy》2011,110(2):242-255
Based on studies of spectral and kinetic parameters of dimers of Zn porphyrins and of multiporphyrin self-assembling complexes
formed on their basis, we find that extra liganding of dimers by pyridine inappreciably lowers the energy of the triplet level
E(T
1). We show that, in this case, the nonradiative deactivation T
1 ↝ S
0 of the electronic excitation energy of dimers Zn porphyrins increases not only due to increasing Franck-Condon factor. We
discuss mechanisms of the quenching action of an extra ligand related to an accepting role played by high-frequency overtones
of vibrations of extra ligand molecules, to an enhancement of the spin-orbit interaction due to energy lowering of σπ* states,
and to out-of-plane distortion of dimers caused by the displacement of the Zn2+ ion out of the plane of the tetrapyrrole macrocycle. Quenching of triplet states of extra liganded dimers of Zn porphyrins
by molecular oxygen in liquid solutions at 295 K depends on the character of donor-acceptor interactions with pyridine and
rigidity of a linking molecular fragment. We find that the rate constants of oxygen quenching of the excited electronic states
S
1 and T
1 of multiporphyrin complexes depend on their structure and composition, as well as steric hindrances, created by dimers (screening
effects) for contact interactions of a π-conjugated system of the free base (extra ligand) with molecular oxygen. Screening
effects of extra ligands by dimer molecules of Zn porphyrins, which reduce the oxygen quenching rate constants k
S
and k
T
, are found to barely affect the singlet-oxygen generation quantum yield γΔ. 相似文献