共查询到20条相似文献,搜索用时 15 毫秒
1.
Yu. V. Lavskaya A. V. Okotrub L. G. Bulusheva E. M. Pazhetnov A. I. Boronin N. I. Denisenko O. V. Boltalina 《Physics of the Solid State》2007,49(6):1195-1200
The structure of the fullerence fluoride C60F24 of the T h symmetry contains two types of chemically different carbon atoms, namely, atoms of isolated double bonds and atoms of CF groups. X-ray photoelectron and x-ray emission spectroscopic studies of C60F24 revealed a difference in the widths of the x-ray bands corresponding to these types of atoms. Nonempirical quantum-chemical calculations performed for C59NF 24 + ions with a hole in the C 1s core level of the fullerence fluoride showed that the difference in the bandwidths may be due to the fact that the vibrational states of the system are different when 1s electrons are removed from chemically nonequivalent atoms. 相似文献
2.
A. M. Lebedev L. P. Sukhanov M. Brzhezinskaya K. A. Menshikov N. Yu. Svechnikov R. G. Chumakov V. G. Stankevich 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2017,11(4):814-822
The current work is dedicated to investigation of the interaction between self-assembled polar molecules of fullerene fluoride C60F18 with the chemically active surface Ni(100) under radiation and heat treatments. X-ray photoelectron spectroscopy is used in combination with quantum-chemical simulation. For the first time, the transformation of an as-deposited dielectric continuous 2D thin film to a 3D island-type assembly with molecular ordering within the islands is shown to take place. The degree of coverage of the Ni surface by C60F18 islands (0.6–0.7) and their height (~6 nm) are estimated. Quantum-chemical simulation shows that the chemisorption energy of the C60F18 molecule on the Ni surface equals ~6.6 eV and fluorine atoms are located at a distance of 1.9 Å above the Ni surface. The results of the investigation provide an opportunity to create nanoscale ordered structures with local changes in the work function. 相似文献
3.
Yu. I. Golovin A. A. Dmitrievskii R. K. Nikolaev I. A. Pushnin 《Physics of the Solid State》2003,45(1):197-200
The suppression of plasticity sensitivity of a C60 fullerite to the action of a magnetic field is revealed. It is found that the C60 fullerite undergoes temporary softening due to irradiation with ultralow (<0.1 cGy) doses of β and γ radiation. 相似文献
4.
This paper discusses the results of calorimetric studies of the 1D C60 (orthorhombic) and 2D C60 (tetragonal and rhombohedral) fullerites, as well as of the graphite-like polyfullerite, which are produced from a starting C60 fullerite subjected to a pressure of 1–8 GPa at temperatures ranging from 300 to 1270 K. The analysis is made primarily of the C p 0 heat capacity measurements performed in adiabatic calorimeters in the 5-to 350-K range. 相似文献
5.
Jin Ni Qiuye Wu Yuguo Li Zhixin Guo Gusheng Tang Ding Sun Fu Gao Jianming Cai 《Journal of nanoparticle research》2008,10(4):643-651
There is growing evidence in recent years that the pristine fullerene may be endowed with strong pro-oxidant capacity to biological
samples. In this investigation we tested the hypothesis that water-soluble fullerene-C60 (nano-C60) may interact with ionizing radiation enhancing its antiproliferative effects. The two tumor cell lines with different radiosensitivity
B16 and SMMU-7721 were treated by a combination of pristine fullerene and 60Co γ irradiation. We measured cell survival rates, apoptotic characteristics, reactive oxygen species (ROS) production and
alteration of cell diameter with or without γ-irradiation. There was reduced survival with B16 and SMMU-7721 cells exposed
to nano-C60, with the inhibitory concentrations reducing the viability by 50% to 65 part per billion (ppb) and 150 ppb respectively.
For cells exposed to nano-C60 prior to γ-irradiation, damage to cell membranes and increased numbers of apoptotic cells were detected by morphologic Hoechst-staining
analysis and Annexin V/propidium iodide double-staining. In cells exposed to nano-C60, there were increased levels of ROS, as measured by fluorescence detection under laser confocal microscopy. Preincubation
with non-toxic pristine C60 before γ-ray caused enlargement of cells with increased diameter. The results show that nano-C60 inhibits the growth of tumor cells at certain concentrations and increases the effects of 60Co γ-irradiation, possibly through the elevated production of cellular ROS and the membrane disruption. Data in this study
indicates a possible consideration of using C60 as a candidate of sensitization modifier in tumor radiation biology. 相似文献
6.
A semi-empirical molecular dynamics model is developed. The central collisions of C60+C60 and He@C60+He@C60 at different incident energies are investigated based on this model. It is found that the dimer structures have been produced
at proper incident energies and these fullerene dimers could be formed by a self-assembly of C60 fullerene and He@C60. The He atom has a significant effect at higher incident energy and this embedded He atom can enhance the stability of the
dimer structure. 相似文献
7.
The reaction of C60, under ultrasonication, with various oxidants, such as 3-chloroperoxy benzoic acid (Fluka 99%), 4-methyl morpholine N-oxide (Aldrich 97%), chromium (VI) oxide (Aldrich 99.9%), and the oxone® monopersulfate compound, causes the oxidation of fullerenes at room temperature. The FAB-MS spectra and HPLC profile confirmed that the products of fullerene oxidation were [C60(O)n] (n=1~3 or n=1). C70 also reacted, under ultrasonication, with various oxidants, but the reaction rate of C70 was lower than that of C60. 相似文献
8.
The optical Raman and photoluminescence (PL) spectra of the high-pressure hydrogenated fullerene C60 are studied at normal conditions and at high pressure. The Raman spectrum of the most stable hydrofullerene C60H36 contains a large number of peaks related to various isomers of this molecule. Comparison of the experimental data with the results of calculations shows that the most abundant isomers have the symmetries S6, T, and D3d. The Raman spectrum of deuterofullerene C60H36 is similar to that of C60H36, but the frequencies of the C-H stretching and bending modes are shifted due to the isotopic effect. The PL spectrum of hydrofullerene C60H36 is shifted to higher energies by approximately 1 eV with respect to that of pristine C60. The effect of hydrostatic pressure on the Raman and PL spectra of C60H36 has been investigated up to 12 GPa. The pressure dependence of the phonon frequencies exhibits peculiarities at approximately 0.6 and 6 GPa. The changes observed at approximately 0.6 GPa are probably related to a phase transition from the initial orientationally disordered body-centered cubic structure to an orientationally ordered structure. The peculiarity at approximately 6 GPa may be related to a pressure-driven enhancement of the C-H interaction between the hydrogen and carbon atoms belonging to neighboring molecular cages. The pressure-induced shift of the photoluminescence spectrum of C60H36 is very small up to 6 GPa, and a negative pressure shift was observed at higher pressure. All the observed pressure effects are reversible with pressure. 相似文献
9.
10.
V. G. Kytin B. M. Bulychev A. V. Krechetov E. A. Konstantinova V. A. Kulbachinskiĭ R. A. Lunin 《Journal of Experimental and Theoretical Physics》2007,105(1):250-252
A series of new heterofullerides with compositions Rb2MC60, K2MC60, and KM2C60 (M = Mg, Be) have been synthesized. Measurements of the temperature dependences of the magnetic susceptibility in the temperature interval from 4.2 to 300 K reveal a superconducting transition in heterofullerides K2MgC60, KMg2C60, K2BeC60, and Rb2BeC60 at temperatures T c = 13–22 K. The electron states with uncompensated spin are studied by the electron paramagnetic resonance technique. The contributions of conduction electrons and localized electrons to the paramagnetic susceptibility are extracted. 相似文献
11.
The morphology of C60 precipitates synthesized by using isopropyl alcohol (IPA) added with water was investigated in order to know the effect of
water on the growth of C60 nanowhiskers (C60NWs) in C60–toluene–IPA solution systems. The stability of C60NWs decreased and granular crystals of C60 were formed in the solutions when IPA added with an excess amount of water was used in the liquid–liquid interfacial precipitation
method. The C60NWs were found to be destabilized with time in the solutions added with water. The C60NWs dried in air showed similar Raman profiles irrespective of the use of IPA with and without water addition. The Raman profiles
of granular C60 single crystals showed the base lines much flatter than those of C60NWs, indicating that C60NWs possess a disordered crystal structure. By optimizing the growth condition, short C60NWs with aspect ratios ranging from 3 to 10 and an average length of about 1.8 μm were successfully fabricated. The short
C60NWs are expected to be applicable for electrodes of organic thick film solar cells. 相似文献
12.
Vladimir A. Kulbachinskii Boris M. Bulychev Vladimir G. Kytin Alexey V. Krechetov Valeriy P. Tarasov Elizaveta A. Konstantinova Yuriy A. Velikodnyi Yuriy B. Muravlev Andrey V. Zoteev 《Central European Journal of Physics》2010,8(1):101-112
Sodium fullerides Na
n
C60 (n = 2, 3) have been synthesized by a liquid phase reaction and investigated with X-ray diffraction (XRD), nuclear magnetic
resonance (NMR), electron paramagnetic resonance, and differential thermal analysis. XRD data indicate that the crystal structure
of Na2C60 at 300 K is face centered cubic (FCC). A phase transition from primitive cubic to FCC crystal structure has been observed
in this work in Na2C60 fulleride at 290 K. The transition is accompanied by the step-like change of paramagnetic susceptibility. The crystal structure
of Na3C60 is more complicated than, and different from, what has been reported in the literature. A nearly seven-fold increase of paramagnetic
susceptibility with increasing temperature has been observed in the Na3C60 fulleride at 240–260 K. In the same temperature range, a new line at about 255 ppm appears in the 23Na NMR spectrum, indicating a significant increase of electron density near the Na nucleus. The observed effect can be explained
by a metal-insulator transition caused by a structural transition. 相似文献
13.
Yu. I. Golovin A. A. Dmitrievskii I. A. Pushnin M. V. Pavlov R. K. Nikolaev 《Physics of the Solid State》2004,46(3):590-593
A reversible variation in the microhardness of C60 single crystals induced by low-dose β irradiation is found to change sign in the vicinity of the phase transition at Tc=250–260 K. Radiation hardening is observed at T<Tc and radiation softening, at T>Tc. The kinetic characteristics of the β-induced variation in the microhardness of C60 and its recovery to the initial value are studied in the temperature range 170–350 K. Both processes are found to be thermally activated. The activation energies are determined and are shown to be different for sc and fcc lattices. 相似文献
14.
Vasily Lavrentiev Jiri Vacik Hiroshi Naramoto Kazumasa Narumi 《Applied Physics A: Materials Science & Processing》2009,95(3):867-873
The structure transformation occurring in fullerene film under bombardment by 50 keV C60+ cluster ions is reported. The Raman spectra of the irradiated C60 films reveal a new peak rising at 1458 cm−1 with an increase in the ion fluence. This feature of the Raman spectra suggests linear polymerization of solid C60 induced by the cluster ion impacts. The aligned C60 polymeric chains composing about 5–10 fullerene molecules have been distinguished on the film surface after the high-fluence
irradiation using atomic force microscopy (AFM). The surface profiling analysis of the irradiated films has revealed pronounced
sputtering during the treatment. The obtained results indicate that the C60 polymerization occurs in a deep layer situated more than 40 nm below the film surface. The deep location of the C60 polymeric phase indirectly confirms the dominant role of shock waves in the detected C60 phase transformation. 相似文献
15.
E. A. Kyzyma M. O. Kuzmenko L. A. Bulavin V. I. Petrenko I. V. Mikheev M. A. Zabolotnyi M. Kubovcikova P. Kopcansky M. V. Korobov M. V. Avdeev V. L. Aksenov 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2016,10(6):1125-1128
The C60 and C70 fullerene-cluster size distribution in aqueous solutions and a physiological medium is studied via dynamic light scattering. The initial aqueous solutions of fullerenes obtained via different methods are found to contain clusters with a characteristic size of about 100 nm. The additional aggregation of fullerenes is observed after their transfer into a physiological medium (0.9% NaCl) and is established to depend on the preparation method. The cluster-size distribution in a fullerene–pectic-acid mixture is found to vary in water and a physiological medium. The results reveal the need for additional studies of the structure and properties of C60 and C70 molecules, as well as their complexes with medicines, in a physiological medium for medical applications. 相似文献
16.
The electron and nuclear dynamics of C60 fullerenes
irradiated with femtosecond laser pulses are investigated with
photoelectron and photoion spectroscopy. The focus of this work is
the detailed exploration of the population mechanism of Rydberg
levels within the excitation process of neutral C60. The effect
of excitation wavelength, intensity, chirp, and polarization on the
kinetic energy distribution of photoelectrons in single-pulse
experiments gives first insight into the underlying processes. In
combination with time-resolved two-color pump-probe spectroscopy
depending on either pump, or probe pulse intensity, a more complete
picture of the interaction can be drawn. The results point towards a
very interesting but nevertheless complex behavior including four
steps: (i) non-adiabatic multielectron excitation of the HOMO
(hu) → LUMO+1 (t1g) transition; (ii)
thermalization within the hot electron cloud on a time scale below
100 fs, followed by a coupling of energy to vibrational modes of
the molecule via doorway state(s); (iii) population of
electronically excited Rydberg states by multiphoton absorption, and
(iv) single photon ionization from the excited Rydberg states. This
excitation process results in a characteristic sequence of
photoelectron lines in the photoemission spectra. The comparison of
the experimental results with recent theoretical work gives
convincing evidence that non-adiabatic multielectron dynamics (NMED)
plays a key role for the understanding of the response of C60
to short-pulse laser radiation. 相似文献
17.
S. I. Oreshkin D. A. Muzychenko A. I. Oreshkin V. I. Panov V. A. Yakovlev R. Z. Bakhtizin 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2018,12(5):866-871
The dynamics of the adsorption and evolution of fluorinated C60F18 fullerene molecules on the Cu(001) surface are studied by real-time ultra-high vacuum scanning tunneling microscopy. Fluorinated fullerene molecules are shown to decompose with time on the Cu(001) surface transforming to C60 molecules. The decay rate depends on the initial molecular coverage. The rapid decay of fluorinated fullerene molecules is observed when the coverage is no higher than 0.2 single layers. As a result, two-dimensional islands consisting of pure C60 molecules are formed on the Cu(001) surface. 2D islands consisting of fluorinated fullerene molecules are formed when the initial molecular coverage is higher than 0.5 single layers. The molecules inside these islands also tend to decompose with time. It is found experimentally that fluorine atoms are removed completely from the initial C60F18 molecules adsorbed on the Cu(001) surface after 250 h when the initial molecular coverage is 0.6 single layers. 相似文献
18.
O. E. Kvyatkovskii M. G. Shelyapina B. F. Shchegolev L. S. Vorotilova I. B. Zakharova 《Physics of the Solid State》2002,44(3):585-587
This paper reports on ab initio cluster calculations of the equilibrium geometry, electronic structure, and vibrational properties of the C60, C60F24, C60Cl24, C60Br24 molecules. 相似文献
19.
I. V. Davydov 《Physics of the Solid State》2007,49(6):1201-1206
The effect of heating of the electronic subsystem on the thermal stability of C60 and C20 fullerenes and a (C20)2 cluster molecule is investigated theoretically. It is demonstrated that the excitation of electrons to upper energy levels in accordance with the Fermi-Dirac distribution function does not lead to a substantial change in the activation energy E a for decay of the C20 fullerene. The stability of the C60 fullerene and the (C20)2 cluster molecule likewise does not change radically. However, the inclusion of corrections associated with the finite sizes of the heat bath leads to the activation energy E a which is in better agreement with the calculated height of the potential barrier preventing the cluster decay. 相似文献
20.
E. A. Katz D. Faiman S. M. Tuladhar S. Shtutina N. Froumin M. Polak 《Physics of the Solid State》2002,44(3):493-496
As part of our ongoing research program to produce semiconductor devices based on C60 thin films, we report here on our first attempts at the intercalative doping of C60 thin films through the diffusion of metals. Two techniques were employed: (a) chemically induced counter electrodiffusion of Cu and I2 into a C60 matrix and (b) Au diffusion under the action of an external electric field. 相似文献