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61.
The group velocity of 93 GHz phonons in liquid 4He has been measured directly at T ? 0.1 K between 0 and 24 bar. Above ~ 12 bar the group velocity falls increasingly below the ultrasonic phase velocity, and at 24 bar the dispersion is consistent with the quadratic deviation below linearity as suggested by neutron scattering. 相似文献
62.
We describe a versatile infrared laser system capable of generating picosecond pulses continuously tunable over the wavelength range 3.3–8.4 μm, with peak powers of 1–20 MW. The IR pulse duration is ~1.3 ps with a time-bandwidth product of ~0.3. The system uses stimulated electronic Raman scattering (SERS) in caesium vapour to shift the frequency of a picosecond dye laser into the infrared. The quantum efficiency of the Raman conversion process exceeds 40% over almost the entire tuning range. This technique can be extended to other tuning ranges in the IR by using different atomic vapours and SERS transitions. 相似文献
63.
Quantal wavefunction, density and flux maps have been computed for the hydrogen exchange reaction. We find that the threshold for appearance of quantal 相似文献
64.
Robert E. Wyatt 《Chemical physics letters》1975,34(1):167-169
Information theory is used to analyze quantum mechanical rotation excitation probabilities for the hydrogen exchange reaction. A linear rotational surprisal is found, and the entropy deficiency of the product rotational distribution is computed. 相似文献
65.
J. K. Wyatt 《The Journal of the Operational Research Society》1961,12(3):186-187
66.
F. N. Timofeev G. S. Simin M. S. Shatalov S. A. Gurevich P. Bayvel R. Wyatt I. Lealman R. Kashyap 《Fiber and Integrated Optics》2000,19(4):327-353
An experimental and theoretical study of the effect of temperature on the static and dynamic characteristics of packaged external fiber grating semiconductor lasers (FGL) is reported on. Operating in single frequency mode, the laser exhibits high output power (> 8 mW), high temperature stability of operating frequency (-3.4 GHz/K), and low static chirp (-60 MHz/mA). The observed hysteresis in wavelength versus temperature dependence is explained in the frame of a time-domain FGL model accounting for asymmetric nonlinear gain. The laser has low dynamic chirp (~16 MHz/mA) under 2.5 GB/s direct modulation, which is the key factor determining low penalty transmission over 312 km of SSM fiber. Dense WDM transmission performed at 2.6 Gbit/s over 117 km of SSM fiber shows that an FGL-based transmitter is a factor of 7 more tolerant to temperature variations than externally modulated DFB lasers. 相似文献
67.
68.
Photochemically Induced Intramolecular Six‐Electron Reductive Elimination and Oxidative Addition of Nitric Oxide by the Nitridoosmate(VIII) Anion
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Wyatt A. Thornley Dr. Thomas E. Bitterwolf 《Angewandte Chemie (International ed. in English)》2015,54(7):2068-2072
UV photolysis of the nitridoosmate(VIII) anion, OsO3N?, in low‐temperature frozen matrices results in nitrogen–oxygen bond formation to give the OsII nitrosyl complex OsO2(NO)?. Photolysis of the OsII nitrosyl product with visible wavelengths results in reversion to the parent OsVIII complex. Formally a six‐electron reductive elimination and oxidative addition, respectively, this represents the first reported example of such an intramolecular transformation. DFT modelling of this reaction proceeds through a step‐wise mechanism taking place through a side‐on nitroxyl OsVI intermediate, OsO2(η2‐NO)?. 相似文献
69.
A Cauchy initial-value approach to the complex-valued quantum Hamilton-Jacobi equation (QHJE) is investigated for multidimensional systems. In this approach, ray segments foliate configuration space which is laminated by surfaces of constant action. The QHJE incorporates all quantum effects through a term involving the divergence of the quantum momentum function (QMF). The divergence term may be expressed as a sum of two terms, one involving displacement along the ray and the other incorporating the local curvature of the action surface. It is shown that curvature of the wave front may be computed from coefficients of the first and second fundamental forms from differential geometry that are associated with the surface. Using the expression for the divergence, the QHJE becomes a Riccati-type ordinary differential equation (ODE) for the complex-valued QMF, which is parametrized by the arc length along the ray. In order to integrate over possible singularities in the QMF, a stable and accurate Mo?bius propagator is introduced. This method is then used to evolve rays and wave fronts for four systems in two and three dimensions. From the QMF along each ray, the wave function can be easily computed. Computational difficulties that may arise are described and some ways to circumvent them are presented. 相似文献
70.
C. Wyatt Shields Danping Sun Kennita A. Johnson Korine A. Duval Aura V. Rodriguez Lu Gao Paul A. Dayton Gabriel P. Lpez 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(31):8208-8211
Nucleation and growth methods offer scalable means of synthesizing colloidal particles with precisely specified size for applications in chemical research, industry, and medicine. These methods have been used to prepare a class of silicone gel particles that display a range of programmable properties and narrow size distributions. The acoustic contrast factor of these particles in water is estimated and can be tuned such that the particles undergo acoustophoresis to either the pressure nodes or antinodes of acoustic standing waves. These particles can be synthesized to display surface functional groups that can be covalently modified for a range of bioanalytical and acoustophoretic sorting applications. 相似文献