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1.
O. A. Bukin I. V. Bazarov N. V. Bodin A. A. Il’in V. I. Tsarev A. Yu. Maior E. N. Bol’shakova 《Journal of Applied Spectroscopy》2000,67(2):320-326
This article reports the results of an experimental investigation of the basic mechanisms that cause the broadening of emission
lines of a laser-induced plasma generated on the surface of rigid targets in a gaseous atmosphere. The contribution of Stark
and resonance mechanisms of emission-line broadening for the resonance doublet Al I 3s23p2P3/2,1/2-3s24s2S1/2 and triplet Mg I 3s3p3P
0,1,2
0
-3s4s3S1 is discussed. The concentrations of neutral Al atoms in the laser-induced plasma are evaluated by the magnitude of resonance
line broadening.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 2, pp. 234–237, March–April, 2000. 相似文献
2.
C. Lazzaroni P. Chabert A. Rousseau N. Sadeghi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,60(3):555-563
A microplasma is generated in the microhole (400 μm diameter) of a
molybdenum-alumina-molybdenum sandwich (MHCD type) at medium pressure
(30–200 Torr) in pure argon. Imaging and emission spectroscopy have been
used to study the sheath and electron density dynamics during the stationary
normal regime and the self-pulsing regime. Firstly, the evolution of the
microdischarge structure is studied by recording the emission intensity of
the Ar (5p[3/2]1–4s[3/2]1)_{1}) line at 427.217 nm, and Ar+
(4p′
2P3/2–4s′
2D5/2)_{5/2}) line at 427.752 nm. The maximum of
the Ar+ line is located in the vicinity of the sheath-plasma edge. In
both regimes, the experimental observations are consistent with the position
of the sheath edge calculated with an ionizing sheath model. Secondly, the
electron density is recorded by monitoring the Stark broadening of the
Hb_\beta-line. In the self-pulsing regime at 150 Torr, the electron
density reaches its maximum value of 4 × 1015 cm-3, a few
tens of ns later than the discharge current maximum. The electron density
then decays with a characteristic decay time of about 2 μs, while the
discharge current vanishes twice faster. The electron density in the
steady-state regime is two orders of magnitude lower, at about 6–8 ×
1013 cm-3. 相似文献
3.
V. S. Vavilov M. V. Chukichev R. R. Rezvanov A. A. Klyukanov K. D. Sushkevich A. Z. Avavdekh 《Physics of the Solid State》1999,41(7):1070-1074
We have investigated cathodoluminescence both in unannealed ZnSe crystals and in crystals annealed in a Bi melt at a temperature
of 1200K for 120 h with subsequent quenching. In the wavelength range 450–480 nm we have detected a new line series I
i
s
-nLO-mPl consisting of the bound-exciton emission line I
i
s
with wavelength λ=455.9 nm and its plasmon and LO-phonon echoes I
i
s
-LO (λ
1=461.3 nm), I
i
s
-2LO (λ
2=466.8 nm), I
i
s
-3LO (λ
3=472.4 nm), and I
i
s
-4LO (λ
4=478.3 nm). We have determined the mean number of emitted LO phonons N
LO=2.2±0.1 per photon. It is shown that the observed finer structure of the band may be due to multiphonon optical transitions.
At low plasma densities (ω
p
≪ω
LO
) the Coulomb interaction causes broadening of the I
i
s
-nLO series. In samples with denser plasma, in which the condition ω
p
⩽ω
LO
is met, multiplasmon satellites of the series I
i
s
-nLO-mPl are observed. Theoretical calculations of the shape of the emission band agree with experiment.
Fiz. Tverd. Tela (St. Petersburg) 41, 1176–1180 (July 1999) 相似文献
4.
The contribution of three-electron diagrams of two-photon exchange to the energy of 2s, 2p
1/2, and 2p
3/2 states of Li-like ions is calculated. The consistent quantum-electrodynamic calculation is performed for the nuclear charge
Z varying over a wide range with the correction for the finite size of the nucleus taken into account. All the contributions
to the energy of the 2p
1/2−2s transition in Li-like ions with Z≥18 calculated to date are collected.
__________
Translated from Optika i Spektroskopiya, Vol. 92, No. 3, 2002, pp. 375–384.
Original Russian Text Copyright ? 2002 by Sysak, Erokhin, Shabaev. 相似文献
5.
Summary Pressure broadening and shift parameters are measured for theJ=1−0 line of CH3C14N at 18.4 GHz, both for the three hyperfine components and for the single line which envelopes the hyperfine components, observed
at higher pressures (p≥40 mTorr). In agreement with theoretical predictions, these parameters are the same for all the observed lines: Γ
p
= (50 ± 5) MHz/Torr,s=(7±2) MHz/Torr. These values are compared with previous measurements, showing a large variance expecially for the shift parameter.
The measured broadening parameter is 40% lower than prediction of the Anderson theory.
Riassunto Sono stati misurati i parametri di allargamento e spostamento per pressione della rigaJ=1−0 del CH3C14N a 18.4 GHz. Tali misure sono state eseguite, sulle tre componenti iperfini e sul loro inviluppo osservato a pressionip≥40 mTorr. In accordo con le previsioni teoriche, questi parametri risultano gli stessi per tutte le righe osservate: Γ p = (50 ± 5) MHz/Torr,s=(7±2) MHz/Torr. Questi valori sono confrontati con quelli delle precedenti misure che mostrano una considerevole dispersione, specialmente per quanto riguarda il parametro di spostamento. L'allargamento per pressione è risultato piú basso di quello previsto dalla teoria di Anderson di circa il 40%.相似文献
6.
Precise temperature and polarization dependences of Raman spectra have been investigated for fully oxygenated twin-free YBa2Cu3O7 single crystals. We have found a striking superconductivity-induced x−y anisotropy in the temperature behavior of the 340 cm−1 line: the magnitudes of the softening and broadening are quite different in the xx-and yy-polarizations. This anisotropy suggests a contribution of the CuO-chain superconductivity with a pairing symmetry different
from that for the CuO2 plane, or indicates that the superconducting gap amplitudes are different in the k
x and k
y directions. The d+s gap symmetry is the only realistic symmetry in the case of Δx≠Δy.
Fiz. Tverd. Tela (St. Petersburg) 40, 403–412 (March 1998)
Published in English in the original Russian journal. Reproduced here with stylistic changes by the Translation Editor. 相似文献
7.
The optical excitation functions (OEFs) for four series of spectral lines of the Zn atom at the transitions 4sn
1
s
1
S
0 → 4s4p
1
P
1∘ (n
1 = 6–10), 4sn
2
s
3
S
1 → 4s4p
3
P
2∘ (n
2 = 6−8), 4sn
3
d
1
D
2 → 4s4p
1
P
1∘ (n
3 = 4−6), 4sn
4
d
3
D
1, 2, 3 → 4s4p
3
P
2∘ (n
4 = 4−7) excited by a monoenergetic (0.04–0.08 eV) electron beam with energies from the excitation threshold to 18–19 eV are
measured. In the energy dependences of the excitation cross sections, the effect of post-collision interaction of slow (scattered)
and fast (emitted after the autoionization state decay) electrons is observed and described. This interaction leads to the
capture of a slow electron into the listed discrete levels and the appearance of maxima in the excitation functions. The energies
of the maxima are used to determine the energies and widths of single autoionization states or their groups by approximate
formulas of the classical approach. The autoionization levels of the zinc atom responsible for the maxima observed are determined.
Possible transfer of the orbital angular momentum between electrons is analyzed. 相似文献
8.
A. A. Borovik 《Optics and Spectroscopy》2010,109(3):319-324
We measure the full autoionization cross section of lithium atoms excited by electrons in the energy range from the first
autoionization threshold at 56.39 to 600 eV. Data are obtained by determining the total intensity of electron spectrum of
autoionization states 1sn
1
l
1
n
2
l
2 detected at the “magic” observation angle of 54.7°. The cross section behavior is characterized by a sharp increase to a
maximum value of 1.7 × 10−18 cm2 in the energy interval of 56.4–60 eV and a subsequent monotonic drop to a value of 10−18 cm2 at 600 eV. We have discovered a “thin” cross section structure that reflects the presence of strong resonances of Li− ions in the near-threshold area of excitation of the lowest energy autoionization states (1s2s2)2S, (1s2s2p)4
P, 1s(2s2p
3
P)2
P), and 1s(2s2p
1
P)2
P. We have established that the contribution of autoionization to the absolute cross section of single ionization of lithium
atoms does not exceed 4%. We perform a comparative analysis of the data with analogous data for potassium and cesium atoms. 相似文献
9.
Roland Schmidt Erik McNellis Wolfgang Freyer Daniel Brete Tanja Gießel Cornelius Gahl Karsten Reuter Martin Weinelt 《Applied Physics A: Materials Science & Processing》2008,93(2):267-275
Self-assembled monolayers (SAMs) of 4-trifluoromethyl-azobenzene-4′-methyleneoxy-alkanethiols (CF3– C6H4–N=N–C6H4–O–(CH2)
n
–SH on (111)-oriented poly-crystalline gold films on mica were examined by X-ray photoelectron spectroscopy (XPS) and X-ray
absorption spectroscopy (XAS). The spectra are analyzed with the help of density-functional-theory calculations of the isolated
molecule. Only one doublet is detected in the sulphur 2p spectra of the investigated SAMs, consistent with a thiolate bond of the molecule to the gold surface. The C 1s XP spectra and the corresponding XAS π
* resonance exhibit a rich structure which is assigned to the carbon atoms in the different chemical surroundings. Comparing
XPS binding energies of the azobenzene moiety and calculated initial-state shifts reveals comparable screening of all C 1s core holes. While the carbon 1s XPS binding energy lies below the π
*-resonance excitation-energy, the reversed order is found comparing core ionization and neutral core excitation of the nitrogen 1s core-hole of the azo group. This surprising difference in core-hole binding energies is interpreted as site-dependent polarization
screening and charge transfer among the densely packed aromatic moieties. We propose that a quenching of the optical excitation
within the molecular layer is thus one major reason for the low trans to cis photo-isomerization rate of azobenzene in aromatic-aliphatic
SAMs. 相似文献
10.
Agnieszka Bartecka Adam Bac?awski Józef Musielok 《Central European Journal of Physics》2011,9(1):131-137
Experimental Stark broadening studies of the infrared CI transition 3s
1
P
1
o
− 3p
1
S
0 at 833.5 nm are reported for the first time. A high-current wall-stabilized arc, operated in a mixture of helium, argon,
carbon dioxide and hydrogen, was applied as the plasma source. Radiation emitted from homogeneous and optically thin plasma
layers was analyzed. Stark broadening studies of the selected CI transition and the hydrogen Balmer β line were performed. As expected from theoretical considerations, the CI line width depends linearly on the electron density
of the plasma. Applying theoretical Stark broadening data for the H
gb
line, the measured Stark widths of the CI line were calibrated for the purpose of electron density determination in low temperature
plasmas. 相似文献
11.
We report the development of a method for recording the low-temperature (T=6 K) near-IR inelastic light scattering spectra and the observation of electronic scattering on the transitions 1s
3/2(Γ8) → 2s
3/2(Γ8) between the ground and excited states of different shallow acceptor centers in a n-type semi-insulating crystal si-GaAs (n=1.0 × 108 cm−3) and in a doped p-InP crystal (p=3.6×1017 cm−3). Moreover, a new line, associated with the transition 1s
3/2(Γ 8) → 2p
3/2(Γ8) and due to a dielectric local mode, recorded for the first time in the spectra of narrow-gap semiconductors, was found in
the residual-frequency band in the p-InP spectrum between TO(Γ) and LO (Γ) phonons.
Pis’ma Zh. éksp. Teor. Fiz. 67, No. 5, 334–339 (10 March 1998) 相似文献
12.
Summary The collision-assisted electric-quadrupole transition 4s
21
S
0→4s3d
1
D
2 of calcium at 4575 ? has been observed using the laser-enhanced ionization technique for the first time. A blue satellite
band due to the interaction of calcium 4s3d
1
D
2 state with argon1
S
0 has also been detected at 4527 ? which is shifted by 48 ? from the isolated atomic calcium line. The line broadening cross-section
for the blue satellite has been calculated by measuring its collisional broadening at various argon pressures. Important processes
involved in the generation of this blue satellite band are qualitatively discussed.
The authors of this paper have agreed to not receive the proofs for correction. 相似文献
13.
A study is reported of the anomalous broadening of Mn2+ EPR lines on the high-temperature side of the paraelectric-incommensurate phase transition in Rb2ZnCl4 crystals. It is shown that the resonant-line broadening is inhomogeneous and due to the contribution of low-frequency fluctuations
corresponding to the central peak in the elementary-excitation spectrum. The data obtained have permitted us to obtain the
critical correlation-length exponent ν=0.64±0.02 corresponding to the 3d XY model of Heisenberg.
Fiz. Tverd. Tela (St. Petersburg) 41, 122–125 (January 1999) 相似文献
14.
A theory is developed for the magnetic resonance line shape in disordered ferroelectric crystals. In a study of the random
fields responsible for inhomogeneous line broadening, nonlinear and spatial correlation effects are taken into account. It
is shown that homogeneous broadening depends on the temperature and on the magnitude and orientation of the external magnetic
field, as well as on the nonlinearity parameters of the ferroelectric material. The resonance line shape is calculated as
the envelope of homogeneously broadened Lorentzian spin packets. Analytic expressions for I
2(ω) and I
3(ω) are introduced to account for nonlinearity and correlation effects of second and third order, respectively. Calculations
are done for centrally symmetric crystals, as well as for those without a center of symmetry. It is shown that homogeneous
broadening is important near the line peak, while the wings are determined mainly by inhomogeneous broadening. Manifestations
of the predicted effects in the spectrum lines of disordered ferroelectric crystals are discussed.
Fiz. Tverd. Tela (St. Petersburg) 40, 340–347 (February 1998) 相似文献
15.
J. Franzke H. D. Wizemann K. Niemax C. Vadla 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,8(1):23-28
The collisional broadening and shift rate coefficients of the 283.39 nm (6p
2
3P0 → 7s
3P1
o
), 364.06 nm (6p
2
3P1 → 7s
3P1
o
), 368.45 nm (6p
2
3P1 → 7s
3P0
o
) and 405.90 nm (6p
2
3P2 → 7s
3P1
o
) Pb lines by He and Ar have been measured by fitting the experimental absorption line shapes to theoretical Voigt profiles.
The absorption measurements were performed in a resistively heated, Pb loaded oven with an integrated dc noble gas discharge
to produce also Pb atoms in the 6p
2
3P1 and 6p
2
3P2 metastable states. The diffusion of the metastable atoms out of the discharge zone into the neutral noble-gas atmosphere
enabled the line-shape and shift measurement of the lines involving the metastable states without the influence of the discharge
plasma. 相似文献
16.
W. Hartig 《Applied Physics A: Materials Science & Processing》1978,15(4):427-432
Using the 4d- and 5s-states of sodium, two different types of two-photon resonance enhanced four-wave mixing have been observed. In the first
type 2v
L =v
IR +v
pIR radiation near 2.34 μm and UV radiation near 320 nm has been detected. In the second typev
P
−v
S
=v
L
+v
IR the UV radiation produced in the first parametric process acted as a pump for stimulated electronic Raman scattering via
the 4p-state of sodium. Resonantly enhanced by the two-photon transition 3s–4s, radiation near 1.18 μm was produced in this scheme. The realisation of a tunable coherent IR source based on these four-wave
mixing processes is discussed. 相似文献
17.
Guang S. He Yiping Cui Paras N. Prasad 《Journal of Experimental and Theoretical Physics》1997,85(5):850-856
The spectral structure of backward stimulated scattering from a 10 cm-long CS2-liquid cell is investigated by using Q-switched 10-ns and 532-nm laser pulses with different spectral linewidths. Under a narrow spectral line (∼0.1 cm−1) pump condition, very strong sharp lines near the pump wavelength (λ
0) position and the first-order stimulated Raman scattering (λ
s1) position can be observed. However, under a wide line (≈1 cm−1) pump condition, only a strong and superbroadening spectral band can be observed mainly in the red-shift side of the pump
wavelength. The different spectral features under these two conditions can be explained by a competition between stimulated
Brillouin, Raman, and Rayleigh-Kerr scattering. Under both pump conditions, the broadening spectral distributions are not
consistent with the predictions given by stimulated Rayleigh-wing scattering theories, but can be interpreted well utilizing
the theoretical model of stimulated Rayleigh-Kerr scattering.
Zh. éksp. Teor. Fiz. 112, 1563–1573 (November 1997)
Published in English in the original Russian journal. Reproduced here with stylistic changes by the Translation Editor. 相似文献
18.
Results are presented of experimental studies of how the spontaneous polarization of β-BaB2O4 (BBO) varies with temperature in the range from 2.5 to 90 K. Values of the pyroelectric coefficient γ
s are calculated, and effective values of the Debye temperature (Θ=112 K) and the Einstein temperature (ΘE=28 K) are estimated. It is shown that the dominant contribution to γ
s comes from acoustic lattice modes. A mechanism is proposed to explain why the temperature dependence of the pyroelectric
effect in linear pyroelectric materials is different from that in ferroelectrics.
Fiz. Tverd. Tela (St. Petersburg) 39, 1631–1633 (September 1997) 相似文献
19.
Y. Gangrsky K. Marinova S. Zemlyanoi M. Avgoulea J. Billowes P. Campbell B. Cheal B. Tordoff M. Bissell D. H. Forest M. Gardner G. Tungate J. Huikari H. Penttilä J. Äystö 《Hyperfine Interactions》2006,171(1-3):209-215
Collinear laser spectroscopy experiments on the ScII transition 3d4s
3D2→3d4p
3F3 at λ ≈ 363.1 nm were performed on the 42–46Sc isotopic chain using an ion guide isotope separator with a cooler–buncher. Isotope and isomer shifts and hyperfine structures
of five ground states and two isomers were measured. Preliminary results on the nuclear moments and charge radii changes deduced
from these measurements are reported. 相似文献
20.
《Il Nuovo Cimento C》1984,7(6):604-610
Summary The temperature of protons, α particles, silicon and iron ions in the solar wind have been determined analysing 140 energy
spectra measured aboard the ISEE-2 spacecraft during 1978 and 1979. The data cover the range of proton temperaturesT
p from 104 K to 105 K, never explored in detail before. The experimental results show that in this range of temperatures and for solar-wind velocitiesv
sw smaller than 370 km s−1, the temperature of the α-particlesT
α is smaller thanT
p.T
α actually increases faster thanT
p withv
sw; however, forv
sw≤420 km s−1 the ratioT
α/T
p is always less than 4, while previous observations at higher temperatures (105 K to 106 K) are consistent with a constant ratioT
α/T
p=4. The temperature of the silicon ions, moreover, tends to become independent ofT
p for proton temperatures greater than 3·104 K.
Paper presented at the 2o Convegno Nazionale di Fisica Cosmica, held at L'Aquila, 29 May–2 June 1984. 相似文献