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1.
Surface plasmon-phonon polaritons (SPPP’s) of types 3 and 4 are investigated in doped anisotropic single crystals of hexagonal
silicon carbide (6H-SiC) in the orientation corresponding to K⊥C and xy⊥C. It is shown that a dispersion dependence of the type-3 SPPP’s bounded by K appears in 6H-SiC when the plasmon frequency increases to ν
p⊥⩾350 cm−1. At ν
p⊥⩾400 cm−1, ν
s(K) exists for type-4 SPPP’s in the frequency range Ω
∥
+
<ν<
⊥
+
. When the concentration of free charge carriers is increased, the dispersion curves are displaced toward higher frequencies.
The conditions for the existence of type-3 and type-4 SPPP’s in 6H-SiC are determined.
Fiz. Tverd. Tela (St. Petersburg) 40, 636–639 (April 1998) 相似文献
2.
Fourier transform infrared spectroscopy studies have been conducted to investigate the interaction among components in a system
of high molecular weight polyvinylchloride (PVC)–lithium trifluoromethanesulfonate (LiCF3SO3) incorporated with different type of plasticizers, namely, ethylene carbonate (EC), propylene carbonate (PC), and dibutylphthalate
(DBP). Interaction between PVC and LiCF3SO3 was confirmed by C–H rocking mode at 1,255 cm−1 for PVC shift to 1,252 cm−1 in PVC–LiCF3SO3. The plasticizers’ carbonyl (C=O) oxygen atom which carries lone pair electrons interact with Li+ of LiCF3SO3 and methine hydrogen of PVC in LiCF3SO3–plasticizer system and PVC–plasticizer system, respectively. Changes in peaks assigned to 1,264 cm−1 (ν
as(SO3)), 1,033 cm−1 (ν
s(SO3)), 1,181 cm−1 (ν
as(CF3)), 1,230 cm−1 (ν
s(CF3)), 765 cm−1 (δ
s(CF3)), 644 cm−1 (δ
s(SO3)), 578 cm−1 (δ
as(CF3)), and 519 cm−1 (δ
as(SO3)) indicate the occurrence of complexation in the PVC–LiCF3SO3 system, LiCF3SO3–plasticizer system, and PVC–LiCF3SO3–plasticizer system. 相似文献
3.
The infrared spectra of tutton salts 1. A comparative study of (NH4)2 M″(SO4)2·6H2O (M″=Ni,Co or Mg)
The infrared spectra of (NH4)2M″(SO4)2.6H2O has been analysed in the region 4000–250 cm−1. The dynamics of each crystal has been discussed in terms of 234 phonon modes, including 3 acoustical ones, using the unit
cell approximation. The ambiguity in the assignments of the bands in the region 900–500 cm−1 has been removed by assigning the bands in this region to the libratory modes of H2O molecules. It has been concluded that the NH
4
+
and SO
4
2−
ions have a symmetry lower thanT
dand also the complex [M″(H2O)6]2+ has a symmetry lower than O
h
. The hydrogen bonding is the strongest in the Ni-salt and the weakest in the Mg-salt. 相似文献
4.
N. N. Achasov 《JETP Letters》1996,63(8):601-606
It is shown that BR(χ
b1(1 P)→e
+
e
−)≃3.3· 10−7 and BR(χ
c1(1 P)→e
+
e
−)≃10−8. This gives realistic possibilities for searching for the production of χ
b1(1 P) and ξ
c1(1 P) states in e
+
e
− collisions, even on the present-day colliders, to say nothing of b and c-τ factories.
Pis’ma Zh. éksp. Teor. Fiz. 63, No. 8, 569–574 (25 April 1996) 相似文献
5.
A. V. Mel’nichuk 《Journal of Experimental and Theoretical Physics》1999,89(2):344-348
The coefficient R(ν) of reflection from the surface of 6H-SiC single crystals is studied in the case in which the long-wavelength optical vibrations
of the lattice are coupled with the electron plasma. It is shown for the first time that the anisotropy of the properties
of electrons and phonons in 6H-SiC gives rise to special features in the spectrum of the coupled vibrations and the transparency
regions. It is found, in particular, that if the axis of the crystal lies in the polarization plane of the incident radiation
(0<θ<90°), for 30 cm−1⩽ν
p⊥<320 cm−1 the spectrum of R(ν) acquires three regions of transparency and opacity, and for ν
p⊥⩾320 cm−1 four such regions, which are absent in an isotropic medium. The width of these regions is found to depend on the electron
concentration in the conduction band and on the angle θ.
Zh. éksp. Teor. Fiz. 116, 646–654 (August 1999) 相似文献
6.
Comparative studies of the emission of quasi-thermal atomic and cluster ions from V, Nb, Ta, Au, and In targets bombarded
by cluster ions Au
m
−(m = 1–9), as well as from Si and Bi targets bombarded by cluster ions Au
m
−(m = 1–9) and Bi
m
−(m = 1–5), with energy E
0 ranging from 6 to 21 keV are carried out. In the case of bombardment by heavy cluster ions, the fraction of the quasi-thermal
component in the energy spectra of sputtered atomic ions reaches 50 (for V, In, and Au), 70 (Nb), or more than 90% (Ta). In
addition, quasi-thermal ions play a considerable part in the emission of small cluster ions Au2+, In2+, In3+, and Bi
n
+(n = 2–7). The results of the generalizing investigation favor the presence of thermal spike conditions at cluster bombardment
and their appreciable contribution to the emission of atomic and small cluster ions. 相似文献
7.
The static conductivity σ(E) and photoconductivity (PC) at radiation frequencies ħω=10 and 15 meV in Si doped with shallow impurities (density N=1016−6×1016 cm−3, ionization energy ε1≃45 meV) with compensation K=10−4−10−5 in electric fields E=10–250 V/cm are measured at liquid-helium temperatures T. Special measures are taken to prevent the high-frequency part of the background radiation (ħω>16 meV) from striking the
sample. It is found that the conductivity σ(E) is due to carrier motion along the D
− band, which is filled with carriers under the influence of the field E. In fields E<E
q
(E
q
≃100–200 V/cm) the carrier motion consists of hops along localized D
− states in a 10–15 meV energy band below the bottom of the free band (energy ε=ε1); for E>E
q
carriers drift along localized D
− states with energy ε∞ε1−10 meV. An explanation is proposed for the threshold behavior of the field dependence of the photo-and static conductivities.
Pis’ma Zh. éksp. Teor. Fiz. 66, No. 4, 232–236 (25 August 1997) 相似文献
8.
We have recorded and investigated the ESR spectrum of vanadium-doped α-RbTiOPO4 single crystals in the temperature interval 77–300 K. Two types of structurally distinct centers, V1 and V2, with a 4:1 ratio
of the peak intensities were observed. The angular dependences of the resonance magnetic fields are described by a spin Hamiltonian
corresponding to axial symmetry with the parameters g
∥1=1.9305, g
⊥1=1.9565, A
∥1=−168.2×10−4cm−1, and A
⊥1=−54.3×10−4cm−1 for V1 centers and g
∥2=1.9340, g
⊥2=1.9523, A
∥2=−169.0×10−4cm−1, and A
⊥2=−55.2×10−4cm−1 for V2 centers. A model of a paramagnetic center is proposed: The vanadium ions replace titanium ions in two structurally
distinct positions Ti1 and Ti2 (V1 and V2 centers, respectively). The possibility that a VO2+ ion forms when α-RbTiOPO4 crystals and crystals of the KTP group (KTiOPO4, NaTiOPO4, α-and β-LiTiOPO4), studied earlier, are doped with vanadium is discussed.
Fiz. Tverd. Tela (St. Petersburg) 40, 534–536 (March 1998) 相似文献
9.
A large stack of lead-emulsion sandwich detector assembly was flown over Hyderabad, India. High energy gamma rays at the float
altitude were unambiguously identified from the cascades they induced, and their energies reliably determined by improved
methods. From an analysis of 163 gamma rays of energy ≳ 30 GeV, it is found that the differential energy spectrum is represented
by the power lawJ
r
(E)= 129·4E
−2·62±0·12 photons m−2 sr−1sec−1 GeV−1 at an effective atmospheric depth of 14·3 g cm−2; this is the first reliable balloon measurement of atmospheric gamma rays in the energy range 40–1000 GeV. After correcting
for the gamma rays radiated by the primary cosmic ray electrons, the production spectrum of gamma rays, resulting from the
collisions of cosmic ray nuclei with air nuclei, at the top of the atmosphere isP
r
(E, 0)=8·2 × 10−4 E2.60±0.09 photons g−1sr−1sec−1 GeV−1. The atmospheric propagation of the electromagnetic component due to the cascade process is also derived from the gamma ray
production spectrum. 相似文献
10.
The fundamental properties of the AlN and GaN compounds with a wurtzite structure under external hydrostatic pressure, uniaxial
mechanical stress σ⊥ along the hexagonal axis, and biaxial mechanical stress σ⊥ in the basal plane of the unit cell have been considered in terms of first-principles calculations in the frame-work of the
density functional theory. The pressures of the phase transitions from the structures of wurtzite and zinc blende to the structure
of rock salt have been obtained. The behavior of the structural parameters, interband transitions, and positions of the charge
neutrality level has been investigated. The calculated pressure coefficients of the band gap are as follows: ∂E
g
/∂p = 40.9 meV/GPa, −∂E
g
/∂σ
| = −4.2 meV/GPa, and −∂E
g
/∂σ
⊥ = 45.2 meV/GPa for AlN and ∂E
g
/∂p = 33.0 meV/GPa, −∂E
g
/∂σ
| = 23.6 meV/GPa, and −∂E
g
/∂σ
⊥ = 9.6 meV/GPa for GaN. The pressure coefficients of the charge neutrality level in almost all cases are substantially smaller
than the corresponding values obtained for the band gap E
g
. 相似文献
11.
Qingrui Zhang Bingcai Pan Shujuan Zhang Jing Wang Weiming Zhang Lu Lv 《Journal of nanoparticle research》2011,13(10):5355-5364
By encapsulating zirconium phosphate (ZrP) nanoparticles into three macroporous polystyrene resins with various surface groups,
i.e., −CH2Cl, −SO3
−, and −CH2N+(CH3)3 three nanocomposite adsorbents (denoted as ZrP–Cl, ZrP–S, and ZrP–N) were fabricated, respectively for lead removal from
water. Effect of the functional groups on nano-ZrP dispersion and effect of ZrP immobilization on the mechanical strength
of the resulting nanocomposites were investigated. The presence of the charged functional groups (−SO3
− and −CH2N+(CH3)3) are more favorable than the neutral −CH2Cl group to improve nano-ZrP dispersion (i.e., to achieve smaller ZrP nanoparticles). ZrP–N and ZrP–S had higher capacity
than ZrP–Cl for lead removal. As compared to ZrP–N, ZrP–S exhibits higher preference toward lead ion at high calcium levels
as a result of the potential Donnan membrane effect. On the other hand, nano-ZrP immobilization would simultaneously reinforce
both the compressive strength and the wear performance of the resulting nanocomposites with the ZrP loadings up to 5 wt%.
The results reported herein would shed some light on the generation of environmental nanocomposites with high capacity and
excellent mechanical strength. 相似文献
12.
Chen Li-chuan A. Rabenau W. Weppner 《Applied Physics A: Materials Science & Processing》1978,17(3):233-237
The ionic and electronic conductivities of Ag2Tl6I10 single crystals have been studied as a function of crystallographic orientation and temperature from 20 to 135°C. EMF as
well as AC and DC techniques have been employed. The highly anisotropic material is predominantly an Ag+-ion conductor parallel toc-direction, with the Ag+ ions moving through linear channels that are not interconnected. The conductivity σ‖c
=1.6×10−7Ω−1cm−1 at 25°C, with an activation enthalpy for σ‖c
of 0.38 eV. The conduction perpendicular toc-direction has been found to be predominantly electronic with a value of σ⊥c
=3×10−9Ω−1cm−1 at 25°C and an activation enthalpy for σ⊥c
of 0.64 eV. This is the first observation of one-dimensional Ag+ conduction and this type of orientation-dependent change from ionic to electronic conduction.
On leave from Institute of Physics, Academia Sinica, Peking, China. 相似文献
13.
Raymond K. Sheline B. Singh P. C. Sood S. Y. Chu 《Czechoslovak Journal of Physics》1999,49(7):1047-1066
Energies of the first 2+, 3− and 4+ states of even-even nuclei are plotted against proton and neutron number. Using this systematics, shell effects and the corresponding
quadrupole and hexadecapole collectivity and deformation effects are compared and contrasted. Also, the correspondingB(E2),B(E3) andB(E4) values are plotted against neutron number and their very different systematics compared. Among the new results are the
presence of hexadecapole collectivity at the 82 proton and neutron closed shells and the presence of the maximum values ofB(E4) at neutron numbers 10, 90–92 and 140–146. Finally, the systematics of the hexadecapole (K=4+) vibrations is compared with that of the quadrupole (K=2+) gamma vibrations in the quadrupole deformed rare earth region.
This research has been supported by the National Sciences and Engineering Research Council of Canada at McMaster University
and by the Department of Atomic Energy, Government of India, at Banaras Hindu University. 相似文献
14.
Photoacoustic spectroscopy of iodine molecule has been studied in gas phase using nitrogen laser-pumped tunable dye laser.
The experiment yielded the vibrational spectrum corresponding toX
1Σ+(0
g
+
)→B
3Π(0
g
+
) transition up to the convergence limit. The photo-acoustic spectrum in the region 17580–18850 cm−1 is presented along with the vibrational analysis. Five of the vibrational bands reported earlier by Venkateswarlu, Kumar
and McGlynn have been partially resolved and the structure of one of them has been analyzed and shown to be due to an overlap
of (14, 2) and (12, 1) bands. The analysis was based on a comparison with the highly resolved spectrum of Gerstenkorn and
Luc. The structure observed in the region 20200–20750 cm−1 which is beyond the convergence limit of the transitionX
1Σ+(0
g
+
)→B
3Π(0
u
+
) has been analyzed as due to two-photon absorption. Most of the bands could be assigned to two transitions both originating
in the ground state and terminating in two different electronic states 1
g
andE(0
g
+
), atT
e=40821 cm−1 (orT
0=41355 cm−1) andT
e=41411 cm−1 (orT
0=41355 cm−1) respectively. 相似文献
15.
A theoretical study is carried out of quantum beats (QB) in the time-dependent intensities of absorption of a test pulse and
of spontaneous luminescence in a Cu2O crystal under conditions of double optical resonance. It is assumed that pumping is effected by a CO2-laser pulse which dynamically couples the exciton levels 1s(Γ
5
+
) and 2p(Γ
4
−
,Γ
5
−
,Γ
3
−
Γ
2
−
) and splits them into two or three pairs of quasi-energy levels. The frequency of the test pulse is in resonance with the
frequency Γ
5
+
of the exciton. The corresponding intensities for various directions of the electric vector of the pump field E
L, the polarization vector ξ, and the wave vector q of the test pulse are obtained. The frequency of the quantum beats is twice the Rabi frequency, which for different values
of E
L, ξ and q contains different sets of matrix elements of the dipole transitions between the levels 1s(Γ
5
+
) and 2p(Γ
4
−
,Γ
5
−
,Γ
3
−
Γ
2
−
). Thus, by measuring the period of the quantum beats it is possible to determine the unknown matrix elements of the indicated
transitions.
Fiz. Tverd. Tela (St. Petersburg) 39, 844–847 (May 1997) 相似文献
16.
N. Hashimoto T.R. Saitoh G. Sletten R.A. Bark M. Bergström K. Furuno T. Komatsubara T. Shizuma S. Törmänen P.G. Varmette 《The European Physical Journal A - Hadrons and Nuclei》1998,2(4):327-330
Abstact: High-spin states in 183Re have been studied using the 176Yb(11B,4n) reaction at 52 and 57 MeV. Two high-K bands have been observed directly by a time-correlated γ-γ coincidence measurement. One of the bands is built on an isomeric
K
π=(25/2)+ state at E
x= 1908 keV with a half-life of 0.82(2) ms. The other band, assigned as K
π=(29/2)− at E
x= 2739 keV, decays to the (25/2)+ band. These bands are interpreted as three-quasiparticle structures, π(5/2)+[402] &⊗ν(9/2)+[624] ⊗ν(11/2)+[615] for the (25/2)+ band and π(9/2)−[514] ⊗ν(9/2)+[624] ⊗ν(11/2)+[615] for the (29/2)− band. The K
π= (29/2)− band becomes strongly Coriolis mixed with increasing spin and is gradually changing into a low-K s-band structure.
Received: 20 April 1998 相似文献
17.
The difference of the energies of levels Δ
n
= E
lev(2+0
n
) − E
lev(0+0
n
) at n = 1, 2, and 3 and the multipole-mixture parameter δ for (2+02−2+01) and (2+03−2+01) transitions are contrasted against the structure of the K
π
= 02+ and 03+ rotational bands that was calculated on the basis of the quasiparticle-phonon model. The values of (Δ2 − Δ1), (Δ3 − Δ1), and (Δ2 − Δ3) are found to correlate with the sign of the parameter δ and with the calculated structure of the K
π
= 02+ and 03+ bands.
Original Russian Text ? A.M. Demidov, L.I. Govor, V.A. Kurkin, I.V. Mikhailov, 2009, published in Yadernaya Fizika, 2009,
Vol. 72, No. 2, pp. 236–240. 相似文献
18.
On the basis of quasipotential approach to the bound state problem in QED we calculate the vacuum polarization, relativistic,
recoil, structure corrections of orders α
5 and α
6 to the fine structure interval ΔE
fs = E(2P
3/2) − E(2P
1/2) and to the hyperfine structure of the energy levels 2P
1/2 and 2P
3/2 in muonic 23He ion. The resulting values ΔE
fs = 144 803.15 μeV, Δ$
\tilde E
$
\tilde E
hfs(2P
1/2) = −58 712.90 μeV, Δ$
\tilde E
$
\tilde E
hfs(2P
3/2) = −24 290.69 μeV provide reliable guidelines in performing a comparison with the relevant experimental data. 相似文献
19.
E. N. Elekina A. A. Krutov A. P. Martynenko 《Physics of Particles and Nuclei Letters》2011,8(4):331-336
On the basis of quasi-potential approach to the bound state problem in QED we calculate the vacuum polarization, recoil and
structure corrections of orders α5 and α6 to the fine splitting interval ΔE
fs = E(2P
3/2) − E(2P
1/2) in muonic 24He ion. The resulting value ΔE
fs = 146180.68 μeV provides reliable guideline in performing a comparison with the relevant experimental data. 相似文献
20.
L. I. Govor A. M. Demidov V. A. Kurkin I. V. Mikhailov 《Physics of Atomic Nuclei》2010,73(7):1101-1105
The results obtained by studying the angular distributions of gamma rays with respect to the neutron-beam axis in the reaction
178Hf(n, n′γ) involving the deexcitation of the K
π
= 0+ rotational bands of 178Hf are presented.New information about themultipole-mixing parameter δ in gamma transitions from the levels of these bands is obtained. The K
π
= 04+ band is constructed anew. The relationship between the parameter δ for the (2+0
n
−2+01) gamma transition and the energy gap Δ
n
= E
lev(2+0
n
) − E
lev(0+0
n
), on one hand, and the quasiparticle structure of the rotational band, on the other hand, is discussed for 178Hf on the basis of the quasiparticle-phonon model. 相似文献