共查询到20条相似文献,搜索用时 15 毫秒
1.
A miniature tunable TEA CO2 laser using isotope 13C16O2 as the active medium is developed to extend the spectral range of CO2 lasers for further application. The optimization of the energy parameters of the tunable TEA 13C16O2 laser and the same laser using 12C16O2 are studied. When a gas mixture (13C16O2: N2: He = 1: 1: 3) at a total pressure of 6.4 × 104 Pa is used, the TEA 13C16O2 laser of a 45-cm3 active volume obtains 51 emission lines in the [0001–1000] and [0001–0200] bands. The maximum pulse energy of the TEA 13C16O2 laser is about 357 mJ. The same laser using the conventional gas mixture (12C16O2: N2: He = 1: 1: 3) at a pressure of 6.66 × 104 Pa is measured to obtain 69 laser emission lines and the maximum pulse energy of laser radiation is about 409 mJ. 相似文献
2.
The torus group (S
1)ℓ+1 has a canonical action on the odd-dimensional sphere S
q
2ℓ+1. We take the natural Hilbert space representation where this action is implemented and characterize all odd spectral triples
acting on that space and equivariant with respect to that action. This characterization gives a construction of an optimum
family of equivariant spectral triples having nontrivial K-homology class thus generalizing our earlier results for SU
q
(2). We also relate the triple we construct with the C
*-extension
相似文献
3.
A. I. Belyaeva K. V. Baranova 《Bulletin of the Russian Academy of Sciences: Physics》2009,73(8):1056-1060
The 90° reorientation of Er3+ spins in ErFeO3 have been directly observed using optical spectroscopy. The peculiarities of the absorption spectrum of ErFeO3 in the region of the 4
I
15/2 → 4
F
9/2 transition of the Er3+ ion in the temperature range of ac-spin reorientation have been studied. It is shown that the spin reorientation phase transition (SRPT) is accompanied by splitting
of the ground and excited states into Kramers doublets in the iron exchange field. This fact is a direct evidence of purely
magnetic origin of SRPT. The experimental results were used to analyze the magnetic properties of ErFeO3. This analysis showed that the order of magnitude of the magnetic moment, its variation in the SRPT region, and the existence
of T
comp can be interpreted in terms of the single-ion model, taking into account the influence of the crystal field and the molecular
field produced by the iron subsystem ions. 相似文献
4.
The possible existence of complexes formed by the C60 fullerene or its derivatives with transition metals interacting with the carbon cage via η6−π type bonding is discussed. The derivatives C60
R
6 of the C60 fullerene (R = −, H, F, Cl, Br, CN) are analyzed using the density functional method within the Perdew-Burke-Ernzerhof approximation.
In these molecules, the R groups are attached to carbon atoms located in the α positions with respect to the common hexagon of the C60 fullerene. The structure and electron configuration of complexes formed by these molecules with Cr(C6H6), Cr(CO)3, MoC6H6, and Mo(CO)3 particles are modeled. The “dimer” systems C60R6-M-R
6C60 (M = Cr, Mo, R =-, H, F) are investigated in which two fullerene molecules interact via a transition-metal atom. It is found that the introduction
of six R groups in the α sites with respect to the common hexagon of C60 favors the formation of complexes of these derivatives of the C60 fullerene with the Cr(C6H6), Cr(CO), Mo(C6H6), and Mo(CO)3 particles in which η6-π type bonds arise between the metal and the atoms of the hexagon fringed with the R groups. It is also demonstrated that analogous complexes with a “bare” C60 fullerene are possible, but they are significantly less stable. The (C6H6) M-R
6C60
R
6-M (C6H6) complexes of particles M(C6H6) (M= Cr, Mo) and derivatives R
6C60
R
6 (R =-, H, F, Cl, Br) are studied. In the R
6C60
R
6 molecule, six R groups are located in the α sites with respect to the common hexagon of the C60 fullerene and six other groups fringe the opposite hexagon. The obtained results can be applied to planning synthesis of
new complexes that C60 fullerene derivatives can form with transition metals.
Original Russian Text ¢ E.G. Gal’pern, A.R. Sabirov, I.V. Stankevich, 2007, published in Fizika Tverdogo Tela, 2007, Vol.
49, No. 12, pp. 2220–2223. 相似文献
5.
Data on the cross sections for single-electron charge exchange and excitation in collisions of He+ ions with C5+, N6+, and O7+ ions in the He+ ion energy range of 0.2–3.0 MeV are obtained for the first time. The cross sections for the single-electron charge transfer
into the singlet and triplet 1snl states of C4+, N5+, and O6+ (2≤n≤5) ions and for the 1s → 2p
0, ±1 electronic excitation of He+(1s) ions are calculated. The calculations were performed by solving close-coupling equations on the basis of ten two-electron
quasi-molecular states. 相似文献
6.
H. G. Bohlen R. Kalpakchieva W. von Oertzen T. N. Massey A. A. Ogloblin G. de Angelis M. Milin Ch. Schulz Tz. Kokalova C. Wheldon 《The European Physical Journal A - Hadrons and Nuclei》2007,31(3):279-302
The structure of 17C has been investigated using the three-neutron transfer reaction (12C,9C) on a 14C target at 231MeV incident energy, the reaction Q-value is Q
0 = - 46.930MeV. Eleven new states up to 16.3MeV excitation energy were identified. The same reaction has also been used on
a 12C target ( Q
0 = - 38.787MeV), and excited states in 15C up to 19MeV were observed. In 17C the three transferred neutrons populate (sd )3 configurations on the 14C core. The comparison of levels populated by the (12C,9C) reaction in 17C, 16C and 15C reveals a strong similarity of their properties. This concerns especially nine states in each of the three carbon isotopes,
which show practically the same excitation energies except a constant mean shift of +5.82MeV for 16C and +6.65MeV for 15C with respect to 17C. The triples of states from the three isotopes, which correspond to each other, have also similar widths and cross-section
ratios. It is concluded that the same (sd )3 structures are populated in the three carbon isotopes. The observed levels of 17C are also compared to the levels of 19O with known assignments and to shell model calculations, and their decay properties are discussed. 相似文献
7.
A. V. Korolev M. I. Kurkin O. B. Sokolov N. B. Orlova 《Physics of the Solid State》2010,52(3):561-567
The dependences of the magnetization M and the magnetic susceptibility χ = ∂M/∂H of pure gadolinium (the concentration of foreign impurities is lower than 0.1 wt %) on the temperature T and the magnetic field H have been measured using a Quantum Design MPMS-5XL SQUID magnetometer. In this material, inhomogeneities of the atomic structure
should not lead to a nonuniform distribution of the magnetic characteristics (including the Curie temperature T
C) over the volume of the sample. The obtained dependences of M and χ have been used to investigate the possibility of suppressing magnetic inhomogeneities of other types by magnetic fields
with a strength of up to 50 kOe. It has been assumed that these inhomogeneities are suppressed when the specific relationship,
namely, the 21/3 rule is fulfilled. The rule relates the portions of the dependence χ(T, H) which at the temperature T = T
C and at the maximum in the curve χ(T) (T = T
m
) depend on H in accordance with the H
2/3 law. It has been shown that the portions separated from the experimental curves χ(T
C, H) and χ(T
m
, H) obey the 21/3 rule. 相似文献
8.
V. V. Afrosimov A. A. Basalaev Yu. G. Morozov M. N. Panov O. V. Smirnov E. A. Tropp 《Technical Physics》2011,56(5):597-604
Time-of-flight mass spectroscopy methods are employed for studying processes occurring during capture of electrons by 3He2+ and Ar6+ multiply charged ions with energy 6z keV (z is the ion charge) from C2H
n
molecules (n = 2, 4, 6) with different multiplicities of C-C bonds. Fragmentation schemes of the molecular ions formed in such processes
are established from analysis of correlations of recording times for all fragment ions. The absolute values of the cross sections
of capture of an electron and capture with ionization are measured, as well as the cross sections of formation of fragment
ions in these processes. The absolute values of total capture cross sections for several electrons are determined. 相似文献
9.
S. A. Kharlamova S. G. Ovchinnikov A. D. Balaev M. F. Thomas I. S. Lyubutin A. G. Gavriliuk 《Journal of Experimental and Theoretical Physics》2005,101(6):1098-1105
Magnetic properties of GdFe3(BO3)4 single crystals were investigated by 57Fe-Mössbauer spectroscopy and static magnetic measurements. In the ground state, the GdFe3(BO3)4 crystal is an easy-axis compensated antiferromagnet, but the easy axis of iron moments does not coincide with the crystal C3 axis, deviating from it by about 20°. The spontaneous and field-induced spin reorientation effects were observed and studied in detail. The specific directions of iron magnetic moments were determined for different temperatures and applied fields. Large values of the angle between the Fe3+ magnetic moments and the C3 axis in the easy-axis phase and between Fe3+ moments and the a2 axis in the easy-plane phase reveal the tilted antiferromagnetic structure. 相似文献
10.
The effects of the 57Fe isotope content and high-frequency magnetic field amplitude h
1 on the shape of the NMR spectrum of multiferroic BiFeO3 at T = 4.2 K are studied by pulsed nuclear magnetic resonance. The NMR spectrum shape and transverse relaxation time T
2 are found to depend strongly on the 57Fe isotope content and h
1 in multiferroic BiFeO3 in the presence of a spatial spin-modulated structure of a cycloid type. In a sample with a high 57Fe isotope content, the Suhl-Nakamura interaction contributes substantially to T
2. When these dynamic effects are taken into account for analysis of the NMR spectrum shape, an undisturbed (without an anharmonicity
effect) spatial spin-modulated structure of a cycloid type is shown to exist in BiFeO3. 相似文献
11.
J. Lecointre H. Cherkani-Hassani S. Cherkani-Hassani D. S. Belic J. J. Jureta P. Defrance 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,60(2):331-345
Absolute cross sections for electron-impact single ionization, dissociative
excitation and dissociative ionization of the ethynyl radical ion
(C2D+)^+) have been measured for electron energies ranging from the
corresponding reaction thresholds to 2.5 keV. The animated crossed
electron-ion beam experiment is used and results have been obtained for the
production of C2D2+, C2+, C2+_2^+ , CD+, C+ and
D+. The maximum of the cross section for single ionization is found to
be (2.01 ± 0.02) × 10-17 cm2, at the incident electron
energy of 105 eV. Absolute total cross sections for the various singly
charged fragments production are observed to decrease by a factor of almost
three, from the largest cross-section measured for C+, over C2+_2^+
and CD+ down to that of D+. The maxima of the cross sections are
obtained to be (14.5 ± 0.5) × 10-17 cm2 for C2+_2^+,
(12.1 ± 0.1) × 10-17 cm2 for CD+, (27.7 ±
0.2) × 10-17 cm2 for C+ and (11.1 ± 0.8) × 10-17 cm2 for D+.
The smallest cross section is measured to
be (1.50 ± 0.04) × 10-18 cm2 for the production of the
doubly charged ion C2+. Individual contributions for dissociative
excitation and dissociative ionization are determined for each
singly-charged product. The cross sections are presented in closed analytic
forms convenient for implementation in plasma simulation codes. Kinetic
energy release distributions of dissociation fragments are seen to extend
from 0 to 6 eV for the heaviest fragment C2+_2^+, up to 11.0 eV for
CD+, 14.2 eV for C+ and 11.2 eV for D+ products. 相似文献
12.
The vibration frequencies of unstable ferroelectric and antiferrodistortion modes and the dependences of the energy on the
ion displacement amplitude have been calculated within the generalized Gordon-Kim model for distortions along eigenvectors
of these modes in the mixed compounds Sr1 − x
A
x
Ti1 − x
/4□
x/4O3 and Sr1 − y
A
2y
/3□
y/3TiO3 (A = Sc3+, In3+, La3+, Bi3+; □ is the vacancy). To compensate an excess positive charge, vacancies are introduced into the Ti4+ or Sr2+ site. Calculations have been performed in the “daverage” crystal approximation for impurity concentrations of 0.25 and 0.50.
To this end, a set of 40 atomic superlattices with various orderings of heterovalent ions Sr2+ and impurity A
3+ has been considered. It has been found that each impurity type, independently of charge balance, induces ferroelectric instabilities
in doped compounds. In the case of doping with In3+ and La3+ for concentration x = 0.25, the possibility of rotating the polarization vector has been shown. 相似文献
13.
Liu Bing Zhang Hong Li WenJian Li Qiang Zhou GuangMing Xie Yi Hao JiFang Min FengLing Zhou QingMing Duan Xin 《中国科学G辑(英文版)》2007,50(2):221-230
The combination of ionizing radiation and gene therapy has been investigated. However, there are very few reports about the combination of heavy-ion irradiation and gene therapy. To determine if the pre-exposure to low-dose heavy ion beam enhances the suppression of AdCMV-p53 on non-small lung cancer (NSLC), the cells pre-irradiated or non-irradiated were infected with 20, 40 MOl of AdCMV-p53. Survival fraction and the relative biology effect (RBE) were determined by clonogenic assay. The results showed that the proportions of p53 positive cells in 12C6 beam induced AdCMV-p53 infected cells were more than 90%, which were significantly more than those in γ-ray induced AdCMV-p53 infected cells. The pre-exposure to low-dose 12C6 beam significantly prevented the G0/G1 arrest and activated G2/M checkpoints. The pre-exposure to 12C6 beam significantly improved cell to apoptosis. RBEs for the 12C6 AdCMV-p53 infection groups were 30%-60%, 20% -130% and 30%-70% more than those for the 12C6 -irradiated only, AdCMV-p53 infected only, and γ-irradiation induced AdCMVp53 infected groups, respectively. The data suggested that the pre-exposure to low-dose 12C6 beam significantly promotes exogenous p53 expression in NSLC, and the suppression of AdCMV-p53 gene therapy on NSLC. 相似文献
14.
The electron paramagnetic resonance (EPR) parameters (g
‖ andg
⊥ factors and hyperfine structure constantsA
‖,A
⊥) for Co2+ in Ca(OH)2 are studied from the second-order perturbation formulas on the basis of the cluster approach. In these formulas, the contributions
to EPR parameters from the state interactions and covalency effects are considered and the parameters related to both effects
are obtained from the optical spectra and impurity structure of the studied system. From the study, it is found that the β
angle between the metal-ligand bond and the C3 axis changes from 61° in a pure crystal to 53.68(26)° in the impurity center of a Co2+-doped Ca(OH)2 crystal because of the impurity-induced local lattice relaxation. The reduction of the angle β in the impurity center is
also supported by the result obtained by analyzing the EPR zero-field splitting for Mn2+ in the same Ca(OH)2 crystal. The EPR parameters of Ca(OH)2:Co2+ are also reasonably explained by considering the suitable local lattice relaxation. 相似文献
15.
I. V. Glavanakov P. Grabmayr Yu. F. Krechetov A. N. Tabachenko 《Bulletin of the Russian Academy of Sciences: Physics》2010,74(6):747-749
Experimental research on positive-pion photoproduction on the oxygen nucleus in the 16O(γ, π+p) reaction at high recoil momenta of the residual nuclear system was performed. The yield for the 16O(γ, π+p) reaction was analyzed using a model that takes Δ-isobar configurations in nuclei ground states into account, together with
the earlier-measured yield of the12C(γ, π+p) reaction. The estimated number of isobars per nucleon N
Δ = 0.012 ± 0.005 was obtained for the 12C nucleus, and 16O N
Δ = 0.018 ± 0.004 was obtained for the 16O nucleus. 相似文献
16.
E. V. Bol’shakova A. V. Malov P. A. Ryabochkina S. N. Ushakov K. N. Nishchev 《Optics and Spectroscopy》2011,110(6):910-916
We examine the oscillator strengths and the intensity parameters Ω
t
(t = 2, 4, 6) of yttrium-aluminum, scandium-containing, and gallium garnet crystals doped with Er3+ ions. A comparative analysis of the oscillator strengths and the intensity parameters Ω
t
(t = 2, 4, 6) of garnets with different contents of Al3+ and Sc3+ ions (Gd2.4Er0.5Sc1.8Al3.3O12, Gd2.4Er0.5Sc1.9Al3.2O12, Gd2.4Er0.5Sc2.0Al3.1O12) is performed, as a result of which the oscillator strengths and the intensity parameters Ω
t
(t = 2, 4, 6) of these crystals are shown to have close values. We find that Ca3(NbGa)5O12 crystals doped with Er3+ ions are characterized by highest values of the oscillator strengths for hypersensitive transitions and of the intensity
parameter Ω2 of Er3+ ions compared to the values of these quantities in the examined garnet crystals, which is determined by the fact that the
symmetry of the local environment of Er3+ ions in these crystals is C
1, C
2, or C
2ν. We reveal that, as the concentration of Er3+ ions in these crystals increases from 1 to 39 at %, both the oscillator strength of the hypersensitive transition 4
I
15/2 → 2
H
11/2 of Er3+ ions and their intensity parameter Ω2 tend to decrease, which can be related to an increase in the relative fraction of Er3+ ions with higher symmetry of the local environment. 相似文献
17.
H. Cherkani-Hassani D. S. Belic J. J. Jureta J. Lecointre P. Defrance 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,58(1):85-94
Absolute cross-sections for electron-impact dissociative ionization of C2
H2+ and C2 D2+ to CH+, C+, C2+ , H+, CH2+
and C2D+ fragments are determined for electron energies ranging
from the corresponding threshold to 2.5 keV. Results obtained in a crossed
beams experiment are analyzed to estimate the contribution of dissociative
ionization to each fragment formation. The dissociative ionization cross
sections are seen to decrease for more than an order of magnitude, from
CH+ (5.37±0.10) × 10-17 cm2 over C+ (4.19±
0.16) × 10-17 cm2, C2D+ (3.94±0.38) ×
10-17 cm2, C2+ (3.82±0.15) × 10-17 cm2
and H+ (3.37±0.21) × 10-17 cm2 to CH2+
(2.66±0.14) × 10-18 cm2. Kinetic energy release
distributions of fragment ions are also determined from the analysis of the
product velocity distribution. Cross section values, threshold energies and
kinetic energies are compared with the data available from the literature.
Conforming to the scheme used in the study of the dissociative excitation of
C2H2+
( C2 D2+ )\left( {\rm C}_2 {\rm D}_2^+ \right), the cross-sections are presented in
a format suitable for their implementation in plasma simulation codes. 相似文献
18.
V. A. Kolombet A. I. Frolov 《Russian Journal of Physical Chemistry B, Focus on Physics》2010,4(6):875-882
The integral equations of liquids (RISM) and molecular dynamics method were used to calculate the mean force potential for
the SO3 and COO hydrophilic groups and the CH3 hydrophobic group in the acetate, methyl sulfonate, and hydrosulfate anions, which form ion pairs with sodium and potassium
cations in water. The carboxyl group selectively binds sodium ions from solutions containing Na+ and K+ ions, in spite of their equal charges, because the potassium ion experiences stronger steric hindrances near this group compared
with sodium. The biophysical consequences of the revealed selectivity are discussed. 相似文献
19.
The spectral functor of an ergodic action of a compact quantum group G on a unital C
*-algebra is quasitensor, in the sense that the tensor product of two spectral subspaces is isometrically contained in the
spectral subspace of the tensor product representation, and the inclusion maps satisfy natural properties. We show that any
quasitensor *-functor from Rep(G) to the category of Hilbert spaces is the spectral functor of an ergodic action of G on a unital C
*-algebra.
As an application, we associate an ergodic G-action on a unital C
*-algebra to an inclusion of Rep(G) into an abstract tensor C
*-category .
If the inclusion arises from a quantum subgroup K of G, the associated G-system is just the quotient space K\G. If G is a group and has permutation symmetry, the associated G-system is commutative, and therefore isomorphic to the classical quotient space by a subgroup of G.
If a tensor C
*-category has a Hecke symmetry making an object ρ of dimension d and μ-determinant 1, then there is an ergodic action of S
μ
U(d) on a unital C
*-algebra having the as its spectral subspaces. The special case of is discussed. 相似文献
20.
V. A. Pushkarchuk S. Ya. Kilin A. P. Nizovtsev A. L. Pushkarchuk V. E. Borisenko C. von Borczyskowski A. B. Filonov 《Optics and Spectroscopy》2005,99(2):245-256
The electronic and spin properties of different nanocrystals of carbon are studied. The properties of these cluster systems are modeled in terms of the ab initio (Hartree-Fock) and semiempirical (PM3, AM1) quantum-chemical methods. The calculations are performed for different carbon nanocluster systems: defect-free and with [NV]? centers, hydrogen passivated (C38H42, C71H84, C86H78), and with a free (unpassivated) surface (C38, C71, C86). The spin properties of unhydrated nanoclusters were studied for the first time. The structure of all the clusters under study was optimized using the total energy minimization principle. It is shown that, in the case of hydrated carbon nanocrystals passivated by hydrogen atoms, diamond-like clusters are formed. The atomic structure of an unpassivated nanocrystal depends on the number of atoms in the cluster, as well as on its initial geometrical parameters. In some cases, clusters with a fullerene-like surface are formed. In hydrogenpassivated diamond nanocrystals with [NV]? centers, the spin density is localized at the nuclei of C atoms nearest to the center vacancies. For the unpassivated counterparts, the spin density is localized at the nuclei of C atoms forming the surface of the corresponding nanocrystal. 相似文献