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91.
G. Zhou D. Wang S. Yang Y. Ren X. Xu Z. Shao X. Zhao M. Jiang Y. Tian F. Hao S. Li P. Shi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,19(3):389-393
Linear and nonlinear optical properties of a new organic dye, trans-4-[p-(N-n-butyl-N-n-butylamino)-styryl]-N-methyl-pyridinium tetraphenylborate solution in dimethyl formamide (DMF) have been studied systematically.
When excited with mode-locked picosecond 1 064 nm laser beam, intense upconversion fluorescence and superradiance can be obtained.
The temporal behaviors of one-photon absorption and two-photon absorption (TPA) fluorescence and superradiance have been studied.
The highest upconversion efficiency was found to be 4.1% at a pump energy of 4 mJ. By using an optical parameter amplifier
(OPA) as the pump laser, the nonlinear transmittance and upconversion efficiencies of the dye solution at different wavelengths
were measured. The strongest linear absorption was found at a wavelength of 930 nm whereas the highest upconversion efficiency
was at 1 030 nm. The 100 nm red-shift for the highest upconversion efficiency wavelength compared with the strongest nonlinear
absorption are caused by excited state absorption.
Received 17 October 2001 and Received in final form 21 December 2001 相似文献
92.
G. van den Hock D. Consalvo D. H. Parker J. Reuss 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1993,27(1):73-78
The excited electronic origin bands of several DABCO containing van der Waals complexes have been observed via (1+1) resonance enhanced multi-photon ionization. Sharp resonances with widths of about 3 cm–1 are seen for DABCO-Rg
n=1,2,3 (Rg is Ar, Kr or Xe), for the DABCO-DABCO dimer and for DABCO-DABCO-Ar. The origins of the rare-gas complexes are blue shifted with respect to the monomer origin. Broad features originating from DABCO-Rg
n
complexes with highn, appear to higher energies than the complex origins, with widths of 120 cm–1. 相似文献
93.
We rewrite the Zwanziger horizon condition in terms of the Kugo–Ojima parameter for color confinement. This enables one to explain which value of the Kugo–Ojima parameter is allowed if the horizon condition is imposed. Although all the calculations are performed in the limit of vanishing Gribov parameter for simplicity, the obtained value is consistent with the result of numerical simulations. Consequently, the ghost propagator behaves like free and the gluon propagator is non-vanishing at low momenta, in harmony with recent lattice results and decoupling solution of the Schwinger–Dyson equation. The Kugo–Ojima criterion is realized only when the restriction is removed. 相似文献
94.
Zhe Cui 《Applied Surface Science》2008,254(10):2911-2916
In this paper, on the basis of our former work, we fabricate four kinds of superhydrophobic surfaces by simple means, and adopt high-speed-current-scouring method to test the durability of the as-prepared samples against external force. There exists obvious difference between these four samples in the durability. Finally, we find that the sample with chemical etching and aminosiloxane coating presents best stability, and its contact angle still maintains 141° even after 32-h scouring by current at a speed of 10 m/s. SEM and XPS are utilized to analyze and explain the difference in the durability of the four samples. 相似文献
95.
G. Zhou Y. Ren D. Wang C. Wang Z. Shao Q. Fang M. Jiang 《Applied physics. B, Lasers and optics》2001,72(8):937-940
Trans-4-[p-(N-hydroxyethyl-N-ethylamino)styryl]-N-methylpyridinium p-toluene sulfonate (abbreviated as HEASPS) is a two-photon-absorption
(TPA) dye newly synthesized by our research group. It possesses a much larger TPA cross-section and much stronger upconversion
fluorescence emission than those of common organic dyes (such as rhodamine) when excited with near-infrared (IR) radiation.
TPA spectrum and upconversion efficiency spectrum of HEASPS solution at different wavelengths have been measured. The largest
molecular TPA cross-section σ2
′ is measured to be 2.06×10-47 cm4 s/photon at 930 nm. At 1064 nm, σ2
′ is 2.71×10-48 cm4 s/photon, which is only one-ninth of that at 930 nm. The upconverted lasing efficiency spectrum has been measured at different
wavelengths. The highest efficiency is 5.1% at 1020 nm, whereas it is 3.5% at 1064 nm. Its optical-power-limiting properties
at 930 nm have also been illustrated.
Received: 30 November 2000 / Published online: 27 April 2001 相似文献
96.
We show that the bichromatic phase control of the spontaneous emission spectrum leads to the sub-half-wavelength atom localization. We consider a three-level Λ-type atom interacting with a bichromatic coupling field and a bichromatic probe field with equal frequency difference. One component of the bichromatic coupling field is a standing-wave field with position dependent Rabi frequency. When the spontaneous emitted photons are detected, the atom is localized in either of the two half-wavelength regions with 50% probability by the variation of the difference between the relative phases of the two bichromatic fields. 相似文献
97.
D. Schrader S. Kuhr W. Alt M. Müller V. Gomer D. Meschede 《Applied physics. B, Lasers and optics》2001,73(8):819-824
Using optical dipole forces we have realized controlled transport of a single or any desired small number of neutral atoms
over a distance of a centimeter with sub-micrometer precision. A standing wave dipole trap is loaded with a prescribed number
of cesium atoms from a magneto-optical trap. Mutual detuning of the counter-propagating laser beams moves the interference
pattern, allowing us to accelerate and stop the atoms at preselected points along the standing wave. The transportation efficiency
is close to 100%. This optical ‘single-atom conveyor belt’ represents a versatile tool for future experiments requiring deterministic
delivery of a prescribed number of atoms on demand.
Received: 6 July 2001 / Published online: 23 November 2001 相似文献
98.
P. Domokos T. Kiss J. Janszky 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,14(1):49-53
A beam of diatomic molecules scattered off a standing wave laser mode splits according to the rovibrational quantum state
of the molecules. Our numerical calculation shows that single state resolution can be achieved by properly tuned, monochromatic
light. The proposed scheme allows for selecting non-vibrating and non-rotating molecules from a thermal beam, implementing
a laser Maxwell's demon to prepare a rovibrationally cold molecular ensemble.
Received 23 August 2000 and Received in final form 17 November 2000 相似文献
99.
A transport theory for atomic matter waves in low-dimensional waveguides is outlined. The thermal fluctuation spectrum of
magnetic near fields leaking out of metallic microstructures is estimated. The corresponding scattering rate for paramagnetic
atoms turns out to be quite large in micrometer-sized waveguides (approx. 100 /s). Analytical estimates for the heating and
decoherence of a cold atom cloud are given. We finally discuss numerical and analytical results for the scattering from static
potential imperfections and the ensuing spatial diffusion process.
Received: 17 July 2000 / Published online: 30 November 2000 相似文献
100.
D. Blaschke M.K. Volkov V.L. Yudichev 《The European Physical Journal A - Hadrons and Nuclei》2003,17(1):103-110
The phase diagram for quark matter is investigated within a simple Nambu-Jona-Lasinio model without vector correlations. It
is found that the phase structure in the temperature-density plane depends sensitively on the parametrization of the model.
We present two schemes of parametrization of the model where, within the first one, a first-order phase transition from a
phase with broken chiral symmetry to a color superconducting phase for temperatures below the triple point at T
t = 55 MeV occurs, whereas for the second one a second-order phase transition for temperatures below T
t = 7 MeV is found. In the latter case, there is also a coexistence phase of broken chiral symmetry with color superconductivity,
which is a new finding within this class of models. Possible consequences for the phenomenology of the QCD phase transition
at high baryon densities are discussed.
Received: 3 January 2003 / Accepted: 21 February 2003 / Published online: 24 April 2003 相似文献