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131.
J.D. Pedarnig H. Göttlich R. Rössler W.M. Heckl D. Bäuerle 《Applied Physics A: Materials Science & Processing》1998,67(4):403-405
2 Cu3O7-δ films have been patterned by means of an arrangement employed in scanning near-field optical microscopy (SNOM). Standard
SNOM probes were modified to achieve high transmission for direct writing by oxygen depletion in N2 atmosphere. The written lines are about 1.5 μm wide and show a semiconductor-like resistivity behavior (δ≥0.5). The morphology
of illuminated regions is about the same as that of the YBCO films.
Received: 3 July 1998/Accepted: 6 July 1998 相似文献
132.
The electron spin resonance (ESR) technique was used to investigate the diffusion of Cr3+ in magnesium oxide (MgO) powders. The ESR absorption intensity was measured for several annealing times and four different temperatures of isothermal annealing: 1223, 1273, 1323 and 1373 K. The activation temperature for diffusion, calculated from the experimental data using a theoretical model based on the Fick equation, was found to be EA=212±9 kJ mol−1. This result is about 30% smaller than similar data obtained for single-crystal MgO using the radioactive-tracer sectioning technique. The difference is attributed to a higher concentration of defects in the powder relative to single crystals. 相似文献
133.
R. Prazeres F. Glotin C. Insa D.A. Jaroszynski J.M. Ortega 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,3(1):87-93
The two-colour operation of a Free-Electron Laser (FEL) has been demonstrated with the “CLIO” infrared facility. A two section
undulator allows the production of picosecond laser pulses at two different wavelengths and simultaneously, in a wavelength range from to , and with a wavelength separation of two colours of up to . The time overlap, between both colours, has been measured on a picosecond time scale and on a microsecond time scale. An
initial pump-probe application experiment has been performed with the two colours: stimulated emission has been measured in
a 3-level Quantum-Well system. This is the best demonstration of the stability and reliability of the two-colour laser operation.
Received: 4 November 1997 / Revised in final form: 31 March 1998 / Accepted: 10 April 1998 相似文献
134.
The g-shifts Δg(=g−gs, where gs≈2.0023 is the free-ion value) of the isoelectronic 3d3 series Cr3+, Mn4+ and Fe5+ in SrTiO3 crystals are calculated from the high-order perturbation formula based on the cluster approach for 3d3 ion in cubic octahedral site. The formula includes not only the contribution from the crystal-field (CF) mechanism, but also that from the charge-transfer (CT) mechanism (which is omitted in the CF theory). From the calculations, it is found that the contribution ΔgCT from the CT mechanism in sign is contrary to the corresponding ΔgCF from the CF mechanism and the relative importance of CT mechanism (characterized by |ΔgCT/ΔgCF|) increases with the increasing valence state (and hence the atomic number) of 3d3 ion. The positive g-shift Δg of SrTiO3:Fe5+ is due mainly to the contribution of CT mechanism. So, for the explanations of g factors of the high valence state 3dn ions (e.g. Mn4+ and Fe5+) in crystals, the contributions from both CF and CT mechanisms should be taken into account. 相似文献
135.
EPR study of the low temperature ferroelectric phase transition in Cu doped Rb2ZnCl4 single crystals
Mariana Stefan Sergiu V. Nistor Dirk SchoemakerIoan Ursu 《Solid State Communications》2003,127(11):695-698
Temperature dependent EPR measurements on copper doped Rb2ZnCl4 single crystals allowed us to evidence and study the P21cn↔C1c1 structural phase transition that takes place in this compound at 74.6 K. From the two types of Cu2+ centers localized at different anionic sites, called Cu2+(I) and Cu2+(II), which are formed in this compound, only the Cu2+(II) centers exhibit observable changes in their EPR spectra, attributable to the symmetry lowering. The observed changes have been related to the soft-mode responsible for the structural phase transition. 相似文献
136.
G.H.C. New M. Noy J.A. Crosse A. Rumley L. Newson Z.-Y. Chen C. Cheung A. Todhunter 《Optics Communications》2009,282(22):4418-4422
We establish the connection between a paper by Kartner et al. [F.X. Kartner, D.M. Zumbuhl, N. Matuschek, Phys. Rev. Lett. 82 (1999) 4428] entitled “Turbulence in mode-locked lasers”, and earlier work on the role of noise in mode-locked laser systems. We present numerical results that broadly support the analytical results of Kartner et al. 相似文献
137.
A reversible and regenerable electrochemical biosensor is fabricated for quantitative detection of antibody based on “triplex-stem” molecular switches. A hairpin-shaped oligonucleotide (hairpin DNA) labeled with ferrocene (Fc) at the 3′-end is fixed on the gold electrode serving as a signal transduction probe. Its hairpin structure leads Fc close to the surface of gold electrode and produces a strong current signal (on-state). A single-strand oligonucleotide modified with two digoxin molecules on the two arm segments (capture DNA) interact with hairpin DNA with the help of Ag+ ions. The “triplex-stem” DNA forms, which separates Fc from the electrode and reduces the electrochemical signal (off-state). Binding of digoxin antibody to digoxin releases capture DNA from the hairpin DNA, creating an effective “off-on” current signal switch. The stability of the “triplex-stem” structure of hairpin/capture DNA is critical to the signal switch and the sensitivity of the method, which can be adjusted conveniently and efficiently by changing Ag+ concentrations. Based on the “off-on” current signal switch, this biosensor is used to detect digoxin antibody sensitively in blood serum. The linear range is 1.0–500 pg with a correlation coefficient of 0.996, and the detection limit is 0.4 pg. Also, this biosensor shows excellent reversibility and reproducibility, which are significant requirements for practical biosensor applications. 相似文献
138.
We have demonstrated an efficient and compact passively Q-switched and mode-locked (QML) 1064 nm Nd:YVO4 laser by using a low temperature grown GaAs (LT-GaAs) saturable absorber as well as an output coupler. Stable QML with envelope duration as short as 10 ns and Q-switched repetition rate of 36 kHz was obtained. It is the shortest envelope duration as far as we know, and it is so short that it can be used as Q-switching pulses directly. At 6.9 W of the incident pump power, average output power of 1.24 W was achieved and the corresponding peak power and energy of a single Q-switched pulse were 3.44 kW and 34.4 μJ, respectively. The mode-locked pulses inside the Q-switched pulse envelope had a repetition rate of 780 MHz. 相似文献
139.
Wei Qun 《Solid State Communications》2006,138(9):427-429
A new crystalline lattice distortion model has been proposed, on the basis of it, the relations between spin Hamiltonian parameters and crystal micro structure have been established. By taking into account slight magnetic interactions, including spin-spin (SS), spin-other-orbit (SOO), and orbit-orbit (OO) interactions, the local structure of Cr3+ ion in YGG crystal has been studied using complete diagonalization method (CDM). The studies show that the local structure in the YGG:Cr3+ crystal is of the compressed trigonal distortion. The ligand oxygen plane moved 0.0138 nm toward Cr3+ ion along C3-axis. Accordingly, the SH parameters in YGG:Cr3+ crystal are explained successfully. 相似文献
140.
Stabilization of a passive harmonically mode-locked laser is demonstrated by directly modulating a 980-nm pump diode laser
used both to provide gain and to optically modulate an intracavity saturable absorber. The results indicate a reduction of
the undesired laser modes by more than 55 dB. The timing jitter was decreased by 9 dB.
Received: 3 April 2002 / Revised version: 30 April 2002 / Published online: 12 July 2002 相似文献