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1.
Two sharp line-like bands calledN andR lines on the red side, a close doublet (B lines) on the violet side and two broad bands are observed for natural ruby. At liquid air temperature the splitting ofR line was found and also three sharp-bands calledR, R′ andB lines are identified with spin-forbidden transitions of2
E,2
T
1 and2
T
2. The two broad bands calledU band andY band are assigned accordingly to the spin-allowed transitions4
T
2 and4
T
1 respectively. The observed bands of natural ruby have been attributed to Cr3+ ion in an octahedral environment with trigonal distortion. The crystal field parameters which gave a good fit to the observed
band positions areB=732 cm−1,C=4.25B,Dq=1830 cm−1,V=−1996 cm−1 andλ=34 cm−1. 相似文献
2.
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
3.
The ultra-broadband phase-sensitive optical parametric amplification and de-amplification of image in a BBO nonlinear crystal
with type I phase-matching are theoretically investigated. Amplified images with a gain of 108 and a bandwidth as broad as 420 nm are realized using a 25 GW/cm
−2 peak pump-power density with 1.125 ps chirped-pulse duration. The spatial resolution after optical parametric amplification
is estimated to be q
0 =200 rad/mm (i.e., 31.8 lines/mm), which corresponds to the size of the minimum resolvable feature of the amplified image
~5 μm. 相似文献
4.
M. Bryushinin V. Golubev Y. Kumzerov D. Kurdyukov I. Sokolov 《Applied physics. B, Lasers and optics》2009,95(3):489-495
We report an experimental investigation of the non-steady-state photoelectromotive force in nanostructured GaN within porous
glass and polypyrrole within chrysotile asbestos. The samples are illuminated by an oscillating interference pattern created
by two coherent light beams and the alternating current is detected as a response of the material. Dependences of the signal
amplitude versus temporal and spatial frequencies, light intensity, and temperature are studied for two wavelengths λ=442 and 532 nm. The conductivity of the GaN composite is measured: σ=(1.1–1.6)×10−10 Ω−1 cm−1 (λ=442 nm, I
0=0.045–0.19 W/cm2, T=293 K) and σ=(3.5–4.6)×10−10 Ω−1 cm−1 (λ=532 nm, I
0=2.3 W/cm2, T=249–388 K). The diffusion length of photocarriers in polypyrrole nanowires is also estimated: L
D=0.18 μm. 相似文献
5.
A. A. Samokhvalov T. I. Arbuzova N. A. Viglin V. V. Osipov N. I. Solin S. V. Naumov V. G. Bamburov N. I. Lobachevskaya O. G. Reznitskikh 《Physics of the Solid State》1999,41(2):262-264
Mg1−x
CuxO solid solutions having an NaCl structure with 0⩽x⩽0.20 are synthesized and Cu-Mg1−x
CuxO structures are prepared for superconductivity studies. The magnetic susceptibility χ, electron paramagnetic resonance (EPR), and electrical conductivity of the solid solutions are studied at temperatures of
5–550 K. It is shown that χ
−1(T) obeys the Curie-Weiss law with a paramagnetic Curie temperature Θ close to zero and an effective magnetic moment μ
eff=1.9 μ
B, close to the 1.73 μ
B of a Cu2+ ion with spin S=1/2. The width ΔH of the EPR line depends weakly on temperature and increases as x is raised. The volume narrowing of the EPR linewidth ΔH is used to estimate the exchange interaction parameter, 3×10−4 eV. The g-factor is close to 2 and is temperature independent. The electrical conductivity of Mg1−x
CuxO at T=300 K is ≈10−11–10−12 Ω−1 cm−1 for x=0 and increases to 10−5–10−6 Ω−1 cm−1 for x=0.15–0.20. The conductivity is p-type. Magnetic shielding is observed in Cu-Mg1−x
CuxO structures with x=0.15 and 0.20. The possible connection of this phenomenon with interference superconductivity in the contact layer of the
structure is discussed.
Fiz. Tverd. Tela (St. Petersburg) 41, 293–296 (February 1999) 相似文献
6.
Silver clad wires of highT
c superconductor Y1Ba2Cu3O7−x
have been fabricated through the powder metallurgy technique. The reacted wires show a midpointT
c of 84K. A critical current density of 26·4 A cm−2 (77K, 0T) is obtained in these wires. The wires, however, turn complete normal only at a current density of 280 A cm−2. The reasons for low critical current density obtained in these wires are discussed. 相似文献
7.
K. R. Allakhverdiev M. Ö. Yetis T. K. Baykara S. M. T. Özbek E. Yu. Salaev 《Laser Physics》2011,21(3):598-600
Two methods of preparation of the devices for visualization of pulsed and continuous near-IR (near infrared) are described
and the results of conversion of pulsed and continuous IR (800–1360 nm) laser radiation into the visible range of spectra
(400–680 nm) by using a transparent substrate covered with the particles (including nanoparticles) of effective nonlinear
materials of GaSe
x
S1 − x
(0.2 ≤ x ≤ 0.8) are presented. Converted light can be detected in transmission or reflection geometry as a visible spot corresponding
to the real size of the incident laser beam. Developed device structures can be used for checking if the laser is working
or not, for optical adjustment, for visualization of distribution of laser radiation over the cross of the beam and for investigation
of the content of the laser radiation. Low energy (power density) limit for visualization of the IR laser pulses with 2–3
ps duration for these device structures are: between 4.6–2.1 μJ (3 × 10−4−1 × 10−4 W/cm2) at 1200 nm; between 8.4–2.6 μJ (4.7 × 10−4−1.5 × 10−4 W/cm2) at 1300 nm; between 14.4–8.1 μJ (8.2 × 10−4–4.6 × 10−4 W/cm2) at 1360 nm. Threshold damage density is more than 10 MW/cm2 at λ = 1060 nm, pulse duration τ = 35 ps. The results are compared with commercially existing laser light visualizators. 相似文献
8.
Summary In order to clarify the effect of 13 GHz microwave irradiation upon model membranes, vibrational Raman spectroscopy was performed
for multilamellar dispersions of dipalmitoylphosphatidylcholine, before and after irradiation. Raman spectra of the phospholipid
dispersions were recorded for the C−H ((2800⊢3100)cm−1) and the C−C ((1050⊢1150)cm−1) stretching modes, above the transition temperatureT
m of the phospholipid, before and after microwave irradiation. An intensity comparison between the irradiated and nonirradiated
sample revealed an increase in the intensity ratioI
2930/I
2880 and a small perturbation in the C−C stretching region, induced by microwaves. It seems reasonable to assume that microwave
irradiation brings about a change in lateral chain-chain interactions, which is possibly due to induced changes at bilayer
curvature. 相似文献
9.
The influence of photoexcited carriers on the dynamics of the absorption spectra of GaAs/AlxGa1−2x
As multilayer quantum wells is investigated experimentally. It is found that at quasiparticle densities all the way up to
1011 cm−2 the saturation of the excitonic absorption is due to both a decrease of oscillator strength and broadening of the excitonic
lines. It is shown that in the case of femtosecond resonance laser exci-tation the decrease of oscillator strength is due
to free electron-hole pairs, while the broadening and energy shift of the excitonic lines are due to the exciton-exciton interaction.
The lifetimes of free electron-hole pairs and excitons (≈65 ps and ≈410 ps, respectively) are determined from the exponential
decrease of the change in the oscillator strength and in the width and energy position of the excitonic lines.
Pis’ma Zh. éksp. Teor. Fiz. 66, No. 3, 139–144 (10 August 1997) 相似文献
10.
A. V. Anan’ev Yu. I. Zhdanov A. P. Gerashchenko K. N. Mikhalev S. V. Verkhovskii E. Yu. Medvedev K. A. Okulova N. I. Chebotaev V. N. Goshchitskii 《JETP Letters》1998,67(3):182-188
The spin-spin relaxation rate 63
T
2
−1
of 63Cu nuclei in CuO2 layers is measured in the normal and superconducting states of the compound YBa2Cu3O6.9 (T
c
onset
=94 K) subjected to radiation-induced disordering by a fast-neutron flux Φ to T
c
onset
=68 K (Φ=7×1018 cm−2) and T
c
onset
<4 K (Φ=12×1018 cm−2). It is found that as the structural disorder increases, the contribution of the indirect spin-spin interaction 63
T
2G
−1
, which is related to the value of the spin susceptibility at the boundary of the Brillouin zone of the copper planes χs(q={π/a; π/a}), decreases slightly at the transition to the superconducting state for the initial sample and remains unchanged for the
weakly disordered sample. This behavior of the short-wavelength contribution to the spin susceptibility attests to the stability
of the x
2−y
2 symmetry of the energy gap against structural disorder, in accordance with proposed theoretical models of Cooper pairing
for high-T
c cuprates.
Pis’ma Zh. éksp. Teor. Fiz. 67, No. 3, 172–177 (10 February 1998) 相似文献
11.
The optical absorption spectrum of Ni2+ ion doped in ammonium zinc sulphate has been studied at room and liquid air temperatures. From the nature and the positions
of the bands a successful interpretation of all the bands could be made assumingO
h
symmetry for the Ni2+ ion in the crystal. The fine splitting of the3
T
1
1 band at liquid air temperature has been successfully interpreted to be due to spin-orbit interaction. The crystal field and
spin-orbit parameters derived areDq=1000 cm−1;B=750 cm−1;C=3.45B andξ=600 cm−1. 相似文献
12.
The magnetic properties of La2−2x
Sr1+2x
Mn2O7 polycrystals (x=0.3–0.4) are studied over a broad temperature range 80–600 K. Quasi-two-dimensional manganites have a complex magnetic structure
that undergoes several transitions from one type of magnetic ordering to another. A specific feature of these manganites is
a hyperbolic dependence of inverse susceptibility in the transition region from the magnetically ordered to paramagnetic state
for T>360 K. This suggests the onset of ferrimagnetism. Electron irradiation to a fluence Φ=1×1018 electrons/cm2 is shown to have no effect on the long-range magnetic order while favoring the formation of paramagnetic polarons and of
an inhomogeneous paramagnetic state.
__________
Translated from Fizika Tverdogo Tela, Vol. 45, No. 8, 2003, pp. 1440–1445.
Original Russian Text Copyright ? 2003 by Arbuzova, Naumov, Arbuzov. 相似文献
13.
V. K. Voronkova Yu. V. Yablokov J. Legendziewicz M. Bozechowska 《Physics of the Solid State》1999,41(12):1976-1979
The new heteronuclear crystal CuPr2(CCl3COO)8·6H2O, constructed of chains containing copper and praseodymium atoms, has been synthesized and investigated by EPR at 9.3 GHz
at temperatures ranging from room temperature down to 10 K. At temperatures T∼300–130 K, EPR spectra are observed which are characteristic of isolated polyhedra of copper ions with g
z=2.330±0.005, g
x,y
=2.053±0.005, A
z=139×10−4 cm−1, and A
x,y
<26×10−4 cm−1. At temperatures T<130 K a complex spectrum is observed, associated with the appearance of weak exchange interactions between the copper ions
in the chain (J
Cu-CuΣS
i·S
i+1), comparable in magnitude with the hyperfine interactions J
Cu-Cu=0.015 cm−1 at T=10 K. The magnitude of the exchange interaction decreases smoothly as the temperature is raised. It is conjectured that orbitals
of the praseodymium ions participate in the process of indirect exchange between the copper ions.
Fiz. Tverd. Tela (St. Petersburg) 41, 2154–2157 (December 1999) 相似文献
14.
The low-temperature dc mobility of the two-dimensional electron system localized above the surface of superfluid helium is
determined by the slowest stage of the longitudinal momentum transfer to the bulk liquid, namely, by the interaction between
the surface and volume excitations of liquid helium, which decreases rapidly with the temperature. Thus, the temperature dependence
of the low-frequency mobility is μdc ≈ 8.4 × 10−11
n
e
T
−20/3 cm4 K20/3/(V s), where n
e
is the surface electron density. The relation T
20/3 E⊥−3 ≪ 2 × 10−7 between the pressing electric field (in kilovolts per centimeter) and temperature (in Kelvins) and the value ω ≲ 108
T
5 K−5 s−1 of the driving-field frequency have been obtained, at which the above effect can be observed. In particular, E
⊥ ≃ 1 kV/cm corresponds to T ≲ 70 mK and ω/2π ≲ 30 Hz. 相似文献
15.
I. G. Gogidze P. B. Kuminov A. V. Sergeev A. I. Elant’ev E. M. Men’shchikov E. M. Gershenzon 《Technical Physics》1998,43(10):1193-1198
A new type of fast detector is proposed. The operation of the detector is based on the change induced in the kinetic inductance
of NbN and YBa2Cu3O7−δ
superconducting films by nonequilibrium quasiparticles produced by electromagnetic radiation. The speed of a NbN detector
is essentially temperature-independent and is less than 1 ps. A model based on the Omen-Scalapino scheme describes well the
experimental dependence of the voltage-power sensitivity of a NbN detector on the modulation frequency of the radiation. A
low equilibrium quasiparticle density and a high quantum yield give detecting power D*=1012W−1 · cm · Hz1/2 at temperature T=4.2 K and D*=1016 W−1 · cm · Hz1/2 at temperature T=1.6 K. The time constant of the low-temperature YBaCuO induction detector is determined only by the electron-phonon interaction
time τ
e-ph
d
in the nodal regions.
Zh. Tekh. Fiz. 68, 63–69 (October 1998) 相似文献
16.
G. B. Scott D. E. Lacklison J. L. Page J. Hewett 《Applied Physics A: Materials Science & Processing》1976,9(1):71-77
The absorption (α) and Faraday rotation (θ) spectra of 14 garnets belonging to the series Bi
x
Sm3-x
Fe5-y
Ga
y
O12 (0<x<1.05, 0.8<y<1.15) have been measured between 15 000 cm−1 and 19 000 cm−1. The figure of merit (θ/α) at 17 850 cm−1 (560 nm) increases linearly with increasing bismuth concentration up tox∼0.6 where it begins to increase less rapidly. For operation of magneto-optic display devices at 17 850 cm−1 there is no advantage in using garnets in this series withx>0.8. The Faraday rotation at 17 850 cm−1 increases linearly with bismuth concentration whereas the absorption coefficient increases more rapidly. The presence of
Bi3+ increases the intensity of all Fe3+ pair transitions in the garnet system as a result of the increased superexchange induced by Bi3+. This is in keeping with the observation that the intensity of the6A1g
(S)→4T1g
(G) transition in (RE)3Fe5O12 (RE=Er, Y, Dy, Gd, Eu) increases on traversing the above RE series as do the Curie temperatures of these iron garnets. 相似文献
17.
18.
P. Ortwein W. Woiwode S. Wagner M. Gisi V. Ebert 《Applied physics. B, Lasers and optics》2010,100(2):341-347
A high-resolution spectrometer based on a vertical-cavity surface-emitting laser (VCSEL) was developed and used to determine
the line strength S(T
0)=12.53(11)×10−21 cm−1/(molec cm−2) and the self-broadening coefficient
g0HCl=0.021787(61)\gamma^{0}_{\mathrm{HCl}}=0.021787(61)
cm−1/atm of the R(3) absorption line in the first rovibrational overtone (2←0) band of H35Cl. Furthermore, the first laser-based high-pressure study on the pressure broadening of HCl by He, N2 and
O2(g0N2=0.07292(5)\mathrm{O}_{2}(\gamma^{0}_{\mathrm{N}_{2}}=0.07292(5)
cm−1/atm,
g0He=0.02113(1)\gamma^{0}_{\mathrm{He}}=0.02113(1)
cm−1/atm,
g0O2=0.03978(6)\gamma^{0}_{\mathrm{O}_{2}}=0.03978(6)
cm−1/atm) is presented covering pressures of up to 1 MPa. The results are compared to previously available low-pressure data. 相似文献
19.
Possible parametric oscillation of 3-THz pulse at synchronous pumping of the ZnGeP2 crystal by a train of short second-harmonic pulses from the CO2 laser has been analyzed. Calculation shows that at changing laser pulse duration τ between 4 and 500 ps and correspondingly pumping energy density (0.5–3.5 J cm−2) THz pulse peak power varies from 3 to 70MW with maximum at τ =9 ps. 相似文献
20.
Md. Salimullah R. R. Sharma V. K. Tripathi 《Applied Physics A: Materials Science & Processing》1981,25(3):361-365
Using the fluid model for the nonlinear response of ions, we have studied the nonlinear scattering of an electromagnetic ion
cyclotron wave off the ion acoustic wave in a plasma. The low frequency nonlinearity arises through the parallel ponderomotive
force on ions and the high frequency nonlinearity arises through the nonlinear current density of ions. For a typical nonisothermal
plasma (T
e/T
i∼10) the threshold for this instability in a uniform plasma is ∼1mW/cm2. At power densities ≳102 W/cm2, the growth rate for backscatter turns out to be ∼104s−1. 相似文献