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71.
A simple hydride system is fabricated to measure the superconducting transition temperature 1c unaer hign pressure using a diamond anvil cell (DAC). The system is designed with centrosymetric coils around the diamond that makes it easy to keep balance between the pick-up coil and the inductance coil, while the superconducting states can be modulated with a low-frequency small external magnetic field. Using the device we successfully obtain the Tc evolution as a function of applied pressure up to 10 GPa for YBa2 Cu3 O6+δ superconductor single crystal. 相似文献
72.
A high-quality ferromagnetic GaMnN (Mn=2.8 at%) film was deposited onto a GaN buffer/Al2O3(0 0 0 1) at 885 °C using the metal-organic chemical vapor deposition (MOCVD) process. The GaMnN film shows a highly c-axis-oriented hexagonal wurtzite structure, implying that Mn doping into GaN does not influence the crystallinity of the film. No Mn-related secondary phases were found in the GaMnN film by means of a high-flux X-ray diffraction analysis. The composition profiles of Ga, Mn, and N maintain nearly constant levels in depth profiles of the GaMnN film. The binding energy peak of the Mn 2p3/2 orbital was observed at 642.3 eV corresponding to the Mn (III) oxidation state of MnN. The presence of metallic Mn clusters (binding energy: 640.9 eV) in the GaMnN film was excluded. A broad yellow emission around 2.2 eV as well as a relatively weak near-band-edge emission at 3.39 eV was observed in a Mn-doped GaN film, while the undoped GaN film only shows a near-band-edge emission at 3.37 eV. The Mn-doped GaN film showed n-type semiconducting characteristics; the electron carrier concentration was 1.2×1021/cm3 and the resistivity was 3.9×10−3 Ω cm. Ferromagnetic hysteresis loops were observed at 300 K with a magnetic field parallel and perpendicular to the ab plane. The zero-field-cooled and field-cooled curves at temperatures ranging from 10 to 350 K strongly indicate that the GaMnN film is ferromagnetic at least up to 350 K. A coercive field of 250 Oe and effective magnetic moment of 0.0003 μB/Mn were obtained. The n-type semiconducting behavior plays a role in inducing ferromagnetism in the GaMnN film, and the observed ferromagnetism is appropriately explained by a double exchange mechanism. 相似文献
73.
C. L. Bell M. Dhib G. Hancock G. A. D. Ritchie J. H. van Helden N. J. van Leeuwen 《Applied physics. B, Lasers and optics》2009,94(2):327-336
Cavity enhanced absorption spectroscopy is performed using an external cavity diode laser operating around 1516 nm. We demonstrate
a sensitivity of 6×10−8 cm−1 Hz−1/2 and utilise a simple method to measure pressure-induced broadening and shift coefficients. The broadening and shift coefficients
for six gases (helium, neon, argon, xenon, oxygen and nitrogen) have been determined at room temperature for four transitions
in the υ
1+υ
3 combination band of ammonia. Comparisons of the broadening coefficients with previous work in this region, where it exists,
show good agreement. The broadening and shift coefficients of nitrogen and oxygen are also in good agreement with calculated
values using the Robert and Bonamy theory. Both the broadening and shift coefficients show a clear trend through the rare
gases, which can be explained in terms of the varying magnitude of the long range attractive forces operating between the
colliding partners. We also demonstrate the application of the Parmenter–Seaver formalism to estimate the potential well depth
of the ammonia dimer from the obtained broadening coefficients. The obtained well depth agrees well with theoretical calculations. 相似文献
74.
F. Lahoz P. Haro-Gonzalez F. Rivera-López S. González-Pérez I. R. Martín N. E. Capuj C. N. Afonso J. Gonzalo J. Fernández R. Balda 《Applied Physics A: Materials Science & Processing》2008,93(3):621-625
Thin films of Er3+-doped lead–niobium germanate have been produced by pulsed laser deposition from Er3+-doped 25PbO2–25Nb2O5–50GeO2 (mol%) transparent glasses with an Er content in the range 0.5–3 wt%. The room-temperature infrared to visible upconversion
properties of these thin films have been investigated under 800-nm laser excitation. An energy transfer upconversion mechanism
has been identified to be responsible for the population of the 4S3/2:2H11/2 excited level, from which an intense green emission occurs. A rate equation analysis supports the proposed mechanism. 相似文献
75.
Infrared laser absorption by a planar molecular jet is studied. The absorption lineshape is narrowed by a factor of 2 to 3, as compared to the absorption lineshape in bulk gas. The infrared absorption of CO2 clusters is observed directly in a jet. The formation of clusters in the jet is monitored for different mixtures and distances from the nozzle.Work supported by Stichting voor Fundamenteel Onderzoek der Materie (FOM) 相似文献
76.
M. Afzelius P.-E. Bengtsson J. Bood J. Bonamy F. Chaussard H. Berger T. Dreier 《Applied physics. B, Lasers and optics》2002,75(6-7):771-778
Rotational coherent anti-Stokes Raman spectroscopy (CARS) is a well-established spectroscopic technique for thermometry at
pre-combustion temperatures and atmospheric pressure. However, at pressures of several MPa, a previous investigation revealed
large discrepancies between experimental data and the theoretical model. A re-evaluation has been made of these data (at room
temperature and in the range 1.5–9 MPa) with two improvements to the spectral code. The first is the inclusion of an inter-branch
interference effect, which is described in detail in Paper I. The second is the use of experimental S1-branch Raman line widths measured at 295 K, with a temperature dependence extracted from semi-classical calculations following
the Robert–Bonamy formalism. It is shown that these two modifications significantly improve the theoretical model, since both
the spectral fits and the accuracy of the evaluated temperatures are considerably improved.
Received: 18 February 2002 / Revised version: 9 July 2002 / Published online: 22 November 2002
RID="*"
ID="*"Corresponding author. Fax: +46-46/2224542, E-mail: mikael.afzelius@forbrf.lth.se 相似文献
77.
F. Ibrahim J. Obert O. Bajeat J.M. Buhour D. Carminati F. Clapier C. Donzaud M. Ducourtieux J.M. Dufour S. Essabaa S. Galès D. Guillemaud-Mueller F. Hosni O. Hubert A. Joinet U. Köster C. Lau H. Lefort G. Le Scornet J. Lettry A.C. Mueller M. Mirea N. Pauwels O. Perru J.C. Potier J. Proust F. Pougheon H. Ravn L. Rinolfi G. Rossat H. Safa M.G. Saint Laurent M. Santana-Leitner O. Sorlin D. Verney 《The European Physical Journal A - Hadrons and Nuclei》2002,15(3):357-360
A PARRNe 1 experiment (Production d'Atomes Radioactifs Riches en Neutrons) aimed at the production of neutron-rich radioactive
noble gases produced by photofission has been performed at CERN. The LEP Pre-Injector (LPI) has been used to deliver a 50
MeV electron beam. The results obtained show clearly that the use of an electron beam to produce neutron-rich fission fragments
for futur RNB facilities is an option that should not be neglected.
Received: 20 July 2001 / Accepted: 5 June 2002 / Published online: 19 November 2002
RID="a"
ID="a"e-mail: ibrahim@ipno.in2p3.fr
Communicated by D. Guerreau 相似文献
78.
U. Köster 《The European Physical Journal A - Hadrons and Nuclei》2002,15(1-2):255-263
For fifty years the isotope separation on-line (ISOL) technique has been used for the production of radioactive-ion beams
(RIBs). Thick-target ISOL facilities can provide very intense RIBs for a wide range of applications. The important design
parameters for an ISOL facility are efficiency, rapidity and selectivity of all steps of the separation process. To achieve
the anticipated beam intensities with the next-generation RIB facilities, the production rate in the ISOL target has to be
increased by orders of magnitude. This is only possible by adapting the projectile beam for optimum production cross-sections
and simultaneously minimizing the target heating due to the electronic stopping power of charged-particle projectiles. ISOL
beams of 75 different elements have been produced up to now and further beam development is under way to produce a still greater
variety of isotopes and to improve existing beams in intensity and purity.
Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002
RID="a"
ID="a"e-mail: Ulli.Koster@cern.ch 相似文献
79.
T. Di Luccio C. Attanasio A. Andreone A.M. Cucolo 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,25(3):263-268
We investigated the vortex lattice ordering induced by an applied current in thick (700-900 nm) Mo-Re films with strong pinning.
Measurements of I-V characteristics as a function of field and at different temperatures were carried out. We found that, as in the case of weakly
pinning amorphous samples, dynamic ordering can occur only if the size of the vortex correlated region is at least two times
the intervortex distance.
Received 20 July 2001 相似文献
80.
S. Knappe M. Stähler C. Affolderbach A.V. Taichenachev V.I. Yudin R. Wynands 《Applied physics. B, Lasers and optics》2003,76(1):57-63
We have studied the dispersion and absorption line shapes of coherent population trapping resonances (dark resonances) in
thermal cesium vapor. Outside the time-of-flight regime the line shapes can be described by a simple phenomenological model:
a sum of a dispersive and an absorptive Lorentzian of identical width and position, whose relative weights depend on the detuning
of the laser frequencies from the optical resonance. This functional form can be derived from a theoretical model for the
full multilevel structure of an alkali atom. The analytical expressions for the parameters of the line shape model show the
same behavior as the experimental data.
Received: 4 October 2002 / Revised version: 30 October 2002 / Published online: 8 January 2003
RID="*"
ID="*"Corresponding author. Fax: +41-26/300-9631, E-mail: robert.wynands@unifr.ch 相似文献