共查询到20条相似文献,搜索用时 31 毫秒
1.
S. Heinz E. Berdermann F. Heine O. Joeres P. Kienle I. Koenig W. Koenig C. Kozhuharov U. Leinberger M. Rhein A. Schröter H. Tsertos 《The European Physical Journal A - Hadrons and Nuclei》1998,1(1):27-37
We present the results of a Doppler-shift correction to the measured e+e−–sum-energy spectra obtained from e+e−–coincidence measurements in 238U +206Pb and 238U +181Ta collisions at beam energies close to the Coulomb barrier, using an improved experimental setup at the double-Orange spectrometer
of GSI. Internal-Pair-Conversion (IPC) e+e− pairs from discrete nuclear transitions of a moving emitter have been observed following Coulomb excitation of the 1.844
MeV (E1) transition in 206Pb and neutron transfer to the 1.770 MeV (M1) transition in 207Pb. In the collision system 238U +181Ta, IPC transitions were observed from the Ta-like as well as from the U-like nuclei. In all systems the Doppler-shift corrected
e+e−–sum-energy spectra show weak lines at the energies expected from the corresponding γ–ray spectra with cross sections being
consistent with the measured excitation cross sections of the γ lines and the theoretically predicted IPC coefficients. No
other than IPC e+e−–sum-energy lines were found in the measured spectra. The transfer cross sections show a strong dependence on the distance
of closest approach (Rmin), thus signaling also a strong dependence on the bombarding energy close to the Coulomb barrier.
Received: 22 July 1997 / Revised version: 15 October 1997 相似文献
2.
Huang Zhiwei Chia Teck Chee Diong Cheong Hoong Lee Sing Zheng Wei Chen Jinkai 《Applied physics. B, Lasers and optics》1998,66(4):471-474
1 Π→X1Σ+ transitions and the continuum spectrum of d3Π→a3Σ+ transitions of the NaK dimer in a heat pipe could be observed in the range of 500–700 nm. The collision-induced enhancement
effects of the intensities Id→a and the quenching effect of the intensities ID→X by collisions with argon buffer gas at different pressures were measured experimentally. Based on the stationary collisional
model and lifetime measurements, the quenching cross sections and cross sections for collision-induced energy transfer between
the D1Π and d3Π states could be estimated.
Received: 13 January 1997/Revised version: 20 October 1997 相似文献
3.
Thermal grating and broadband degenerate four-wave mixing spectroscopy of OH in high-pressure flames
H. Latzel A. Dreizler T. Dreier J. Heinze M. Dillmann W. Stricker G.M. Lloyd P. Ewart 《Applied physics. B, Lasers and optics》1998,67(5):667-673
2 ∑–X2Π(0,0) band of OH has been studied in premixed methane/air flames using a cw Ar+ laser probe. Measurements of flame temperature and pressure were derived from fits of theoretical simulations to the observed
time variation of signals over a pressure range of 10 to 40 bar and for different stoichiometry that were in agreement with
independent measurements using N2 CARS and predictions of a one-dimensional flame calculation. Broadband DFWM spectra in the same band of OH were observed
up to a pressure of 9 bar, above which signals were obtained only from scattering from thermal gratings.
Received: 10 November 1997/Revised version: 28 May 1998 相似文献
4.
P. A. Prudkovskii O. V. Skugarevskii A. N. Penin 《Journal of Experimental and Theoretical Physics》1997,85(4):812-817
An amplification of the intensity of pump oscillations is observed experimentally at frequencies from 100 Hz to 1 kHz during
photoinduced light scattering and holographic-type parametric scattering in photorefractive lithium tantalate and niobate.
Possible ways are analyzed for explaining the existence of a photorefractive response in these crystals over times of 10−2–10−3 s, which are five orders of magnitude shorter than the Maxwell time.
Zh. éksp. Teor. Fiz. 112, 1490–1498 (October 1997) 相似文献
5.
Prediction and Measurement of Electron Density and Collision Frequency in a Weakly Ionised Pine Fire
Kgakgamatso Mphale Mohan Jacob Mal. Heron 《International Journal of Infrared and Millimeter Waves》2007,28(3):251-262
Pine litter flame is a weakly ionised medium. Electron-neutral collisions are a dominant form of particle interaction in the
flame. Assuming flame electrons to be in thermal equilibrium with neutrals and average electron-neutral collision frequency
to be much higher than the plasma frequency, the propagation of microwaves through the flame is predicted to suffer signal
intensity loss. A controlled fire burner was constructed where various natural vegetation species could be used as fuel. The
burner was equipped with thermocouples and used as a cavity for microwaves with a laboratory quality network analyzer to measure
wave attenuation. Electron density and collision frequency were then calculated from the measured attenuation. The parameters
are important for numerical prediction of electromagnetic wave propagation in wildfire environments. A controlled pine litter
fire with a maximum flame temperature of 1080 K was set in the burner and microwaves (8–10.5 GHz) were caused to propagate
through the flame. A microwave signal loss of 1.6–5.8 dB was measured within the frequency range. Based on the measured attenuation,
electron density and electron-neutral collision frequency in pine fire were calculated to range from 0.51–1.35 × 1016 m−3 and 3.43–5.97 × 1010 s−1 respectively. 相似文献
6.
The baryon decays of hypernuclear resonances with the configurations s⃛p−1, p⃛p−1, and s⃛s−1 are analyzed within the framework of a translationally invariant shell model. Particular attention is paid to the influence
of the nuclear structure on the decay probabilities in different channels.
Joint Institute of Nuclear Research, Dubna. Institute of Nuclear Physics, Czech, Republic, Rzhezh. Institute of Nuclear Research,
Russian Academy of Sciences, Moscow. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 35–51, October,
1997. 相似文献
7.
A. Brockhinke A.T. Hartlieb K. Kohse-Höinghaus D.R. Crosley 《Applied physics. B, Lasers and optics》1998,67(5):659-665
2 in a flame, excited by a tunable KrF laser near 248 nm. The first comprises several P and R lines of the (1,0) band of the
e 3Πg-a 3Πu Fox–Herzberg system, with fluorescence bands extending past 350 nm. The second is the band head region of the (7,1) band
of the D 1Σu
+←B′ 1Σg
+ system, with fluorescence at 232 nm from D to the X 1Σg
+ ground state. Neither band has been previously observed in any environment. The flame in these experiments is highly sooting,
and the C2 seen here is likely produced by laser vaporization of the soot with subsequent laser photolysis of a C2 precursor. In a rich flame, this fluorescence could cause interferences in other studies such as KrF laser Raman scattering.
Moreover, signal level calculations suggest native C2 near 10 ppm could be readily observed using the Fox–Herzberg excitation. Raman measurements of major species (X≥0.01) in
the same flame, using the KrF laser, are in good agreement with a model prediction.
Received: 2 April 1998/Revised version: 8 June 1998 相似文献
8.
J. Cederkäll M. Lipoglavšek M. Palacz J. Persson J. Blomqvist A. Ataċ C. Fahlander H. Grawe A. Johnson W. Klamra J. Kownacki A. Likar L.–O. Norlin J. Nyberg R. Schubart D. Seweryniak G. de Angelis P. Bednarczyk Z. Dombrádi D. Foltescu M. Górska D. Jerrestam S. Juutinen E. Mäkelä B. M. G. Perez M. de Poli H. A. T. Shizuma Ö. Skeppstedt G. Sletten S. Törmänen 《The European Physical Journal A - Hadrons and Nuclei》1998,1(1):7-9
New excited states have been observed in the neutron deficient isotope 98Ag following the 58Ni+50Cr →108Te* heavy–ion reaction. One of these states may be interpreted as a maximum spin aligned state of the πg9/2
−3νg7/2 configuration. Other possible interpretations within the nuclear shell model are discussed as well.
Received: 24 October 1997 相似文献
9.
A fast tomographic reconstruction device has been developed to detect the two-dimensional distribution of the chemiluminescence
of OH* in the reaction zones of flames. In the set-up, special emphasis was placed on the applicability of the technique to turbulent
flames. A spatial resolution of the system, <1–2 mm, and an exposure time of 100–200 μs are required to resolve the chemiluminescence
signal of OH* originating from the folded flame front of a turbulent flame. 相似文献
10.
The dynamics of near-surface plasma formation and the formation of an erosion plasma flame was investigated for quasi-continuous
laser radiation (λ=1.06 μm, q=0.1–10 MW/cm2, τ∼1.5 msec) acting on bismuth targets in air. The absence of low-threshold plasma formation at q<2 MW/cm2 was established and explained. Instabilities in the plasma formation were revealed and the range of laser radiation power
densities (2≤q≤4 MW/cm2) at which these instabilities take place was determined. At q≥5.4 MW/cm2, brightening of the flame was noted. The dependence of the luminescence temperature of the flame on the laser radiation power
density q was determined.
Institute of Molecular and Atomic Physics, National Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 1, pp. 126–133, January–February, 1998. 相似文献
11.
K. Yamasaki S. Juodkazis T. Lippert M. Watanabe S. Matsuo H. Misawa 《Applied Physics A: Materials Science & Processing》2003,76(3):325-329
We report the reversible micro-structuring of a synthetic rubber polymer (cis1,4-polybutadiene (PB)) by femtosecond laser
illumination. Visco-elastic relaxation of the optically damaged region was observed. The recovery time, typically 102–104 ms, can be varied by changing the irradiation pulse energy. Multi-shot-induced damage recovers on the much longer scale of
101–102 s. It was found that the doping of PB by 4 wt. % of pentazadiene ([4-NO2]–phenyl–N=N–N(C3H7)–N=N–phenyl–[4-NO2]) reduces the threshold of light-induced photo-modification by 20%. This is explained by photo-induced (homolytic) cleavage
of the pentazadiene bonds and formation of gaseous N2, which facilitates material failure at the irradiated spot.
The recovery of optical transmission can be applied to optical memory, optical and micro-mechanical applications. The underlying
mechanism of the phenomenon is discussed in terms of anelastic α- and β-relaxation (polymer backbone and chains/coils relaxation,
respectively).
Received: 11 October 2001 / Accepted: 9 July 2002 / Published online: 25 October 2002
RID="*"
ID="*"Corresponding author. Fax: +81-88/656-7598, E-mail: misawa@eco.tokushima-u.ac.jp 相似文献
12.
A. N. Murashkevich A. S. Lavitskaya T. I. Barannikova I. M. Zharskii 《Journal of Applied Spectroscopy》2008,75(5):730-734
The composites xTiO2-(1−x)SiO2 (x = 0.1, 0.5, 0.9) were obtained by coprecipitation from solutions of alkoxides: tetraethoxysilane (TEOS) and titanium tetraisopropoxide
(TIPT). Intermolecular interaction of the components of the composite is apparent in the IR absorption spectra in the 928–952
cm−1 region, and is connected with bending vibrations of the Si-O-Ti bond.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 5, pp. 724–728, September–October, 2008. 相似文献
13.
2 Σ+(v’=1) level of OH. Measurements were performed in a laminar premixed flame at 10 Torr total pressure. The low pressure allowed
the spatial variation of the effective quenching rate to be determined through the flame front. In addition, the dependence
of the quenching rate on rotational quantum number was measured by exciting a series of rotational lines in the range N’=0–16.
The results show that the total quenching rate decreases only 17% through the flame front, in the region where OH can be detected.
Nevertheless, the absolute value of the quenching rate Q is required if absolute concentrations are to be determined from
LIF-signals. The variation both of Q and of the rotational relaxation rate with excited rotational quantum state must be known
for quantification of LIF-temperature measurements via the Boltzmann relation. Finally, the rotational and vibrational energy
transfer (RET, VET), was investigated by recording the spectrally and temporally resolved fluorescence. For all excited rotational
lines, efficient RET to neighbouring rotational states was observed, but only very little VET. Total RET rates were determined
from the difference between the time-resolved broadband (total fluorescence) and narrowband (fluorescence from the laser excited
level) curves. The experimental results were compared with simulations using a dynamic model, which describes the energy transfer
for flame conditions. With the available input data (temperature, major species concentrations and collision-partner specific
RET cross sections), good agreement was obtained.
Received: 3 February 1997/Revised version: 3 September 1997 相似文献
14.
G. A. Zalesskaya V. S. Ulashchik N. P. Mit’kovskaya O. V. Laskina A. V. Kuchinskii 《Journal of Applied Spectroscopy》2007,74(5):738-743
We used IR Fourier absorption spectra of blood to study changes in the structure of globular blood proteins with extracorporeal
autohemomagnetotherapy, used to treat ischemic heart disease. We compare the spectra of blood before and after magnetotherapy
in the regions: amide I (1655 cm−1), amide II (1545 cm−1), amide III (1230–1350 cm−1), amide IV and amide V (400–700 cm−1). We have shown that pronounced changes in the spectra in the indicated regions on direct exposure of blood in vivo to a
low-frequency pulsed magnetic field are connected with conformational changes in the secondary structure of globular blood
proteins, which are apparent in the increase in the contribution of the α-helix conformation. We discuss the magnetotherapy-initiated
appearance of new IR absorption bands at 1018 and 1038 cm−1 and an increase in the intensity of a number of other bands located in the 1000–1200 cm−1 region, which suggests a change in the concentration of some blood components.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 5, pp. 665–669, September–October, 2007. 相似文献
15.
The results of experimental investigations and an analysis of the temperature dependences of the thermally stimulated depolarization
current are presented for zinc-oxide ceramics suitable for use in high-voltage varistors. A model for the depolarization phenomena
is proposed that takes into account charge exchange on localized electronic states on both sides of the intercrystallite potential
barrier. The model is used to obtain estimates of the ionization energy and density of shallow (∼0.07 eV, 1×1017 cm−3) and deeper (∼0.2 eV, 1×1018 cm−3) bulk levels and surface-localized levels (∼0.1 eV, 1×1013 cm−2).
Zh. Tekh. Fiz. 67, 60–63 (October 1997) 相似文献
16.
3 cm-l for a wavelength of λR≈200 Å in a time ≲1 ps can be expected. The measurable gain Greal depends on the cluster density Ncl. For Ncl≈1016 cm-3 we expect Greal≳20 cm-1.
Received: 30 October 1997 相似文献
17.
Production, isolation, and characterization of group-2 metal-containing endohedral metallofullerenes
T. John S. Dennis H. Shinohara 《Applied Physics A: Materials Science & Processing》1998,66(3):243-247
80 , Ca/Sr/Ba@C82, Ca/Sr/Ba@C84) are investigated for the first time by UV-Vis-NIR absorption spectroscopy and high-resolution 13C NMR. Direct evidence of the endohedral nature and cage structures are revealed by these measurements. Furthermore, we have
found that each metallofullerene has 2–4 structural isomers, which have been isolated by multistage high-performance liquid
chromatography. These isomers have different cage structures and give characteristic UV-Vis-NIR absorption spectra.
Received: 22 September 1997/Accepted: 16 October 1997 相似文献
18.
B. Aengenvoort W. Korten H. Hübel S. Chmel A. Görgen U.J. van Severen W. Pohler R. Zinken T. Härtlein C. Ender F. Köck P. Reiter D. Schwalm F. Schindler J. Gerl R. Schubart F. Azaiez S. Bouneau J. Duprat I. Deloncle 《The European Physical Journal A - Hadrons and Nuclei》1998,1(4):359-364
Three mini-orange conversion–electron spectrometers and four Euroball Ge Cluster detectors have been used for γ–e- coincidence spectroscopy of superdeformed 135Nd. Transitions within the superdeformed band are shown to have the expected E2 multipolarity. The 766.5–keV transition which
links the band to a positive-parity state has a conversion coefficient consistent with M1 multipolarity. Consequently, positive
parity is deduced for the superdeformed band. No evidence for E0 transitions was found.
Received: 22 December 1997 / Revised version: 19 January 1998 相似文献
19.
R.O. Johnson S.J. Karis G.P. Perram W.B. Roh 《Applied physics. B, Lasers and optics》1998,66(4):411-415
2 laser operating on the 1001-1000 transition at λ=4.3 μm and pumped by E –V energy transfer from Br(2P1/2) has been demonstrated. The dynamics and performance of this device were characterized by observing the time-resolved stimulated
emission and the steady-state spontaneous side fluorescence after photolysis of IBr or Br2 by a frequency-doubled Nd:YAG laser or Ar+ laser, respectively. Although the E –V excitation kinetics are favorable, rapid vibrational relaxation limits laser action
to CO2 pressures of less than 1 Torr. Numerical modeling of laser pulse shapes and the dependence on IBr and CO2 pressure and photolysis energy establish a relatively high gain of 0.33%/cm, a CO2-pressure-dependent optical loss of 0.04–0.06%/cm, and an efficiency of 2×10-5 4.3-μm-laser photons per incident photolysis photon. The CO2 fluorescence after photolysis of a fixed Br2/CO2 gas mixture decreases as a function of photolysis time by about 30%/h, indicating the photolytic production of an important
quencher.
Received: 23 June 1997/Revised version: 23 September 1997 相似文献
20.
Z. Liu X. Sun X. Zhou X. Lei Y. Guo Y. Zhang X. Chen H. Jin Y. Luo S.X. Wen C.X. Yang G.J. Yuan G.S. Li X.A. Liu W.D. Luo Y.S. Chen 《The European Physical Journal A - Hadrons and Nuclei》1998,1(2):125-135
High-spin states of 117Xe were investigated by means of in-beam γ-ray spectroscopic techniques via the reaction of 28Si bombarding a 92Mo target at beam energies of 100-120 MeV. A positive-parity rotational band decaying into the yrast negative-parity band
by a series of enhanced E1 transitions was observed for the first time, implying the existence of octupole correlations in
117Xe. The B(E1) values increase with spin. The νd5/2 band was firmly established up to 27/2+ and the B(M1)/B(E2) ratios were extracted from the relative intensities of γ-rays in this band. The previously known νh11/2 and νg7/2 [413]5/2+α=−1/2 bands were confirmed and extended up to high spins and two bandcrossings are observed in the latter at ħω=0.33 and
0.44 MeV, respectively. The bandcrossings and configurations of these bands are discussed by TRS and CSM calculations. In
a γ–γ–t measurement, the 11/2− and 7/2− levels were identified as two isomers with half-lives of 59.4±20 ns and 16.5±8.0 ns, respectively.
Received: 17 June 1997 / Revised version: 29 September 1997 相似文献