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931.
G.W. Baxter M.A. Payne B.D.W. Austin C.A. Halloway J.G. Haub Y. He A.P. Milce J.F. Nibler B.J. Orr 《Applied physics. B, Lasers and optics》2000,71(5):651-663
Optical parametric oscillator (OPO) and amplifier (OPA) devices are useful for spectroscopic sensing of chemical processes
in laboratory, industrial, and environmental settings. This is particularly true of nanosecond-pulsed, continuously tunable
OPO/OPA systems, for which we survey a variety of instrumental strategies, together with actual spectroscopic measurements.
The relative merits of OPO wavelength control by intracavity gratings and by injection seeding are considered. A major innovation
comprises an OPO with a ring cavity based on periodically poled lithium niobate (PPLN) and injection-seeded by a single-mode
tunable diode laser (TDL). Active cavity control by an ‘intensity dip’ method yields an optical bandwidth ≤0.005 cm-1 (150 MHz), which compares favourably with the performance of advanced grating-tuned OPO/OPA systems. A novel adaptation of
this TDL-seeded PPLN OPO employs a compact, inexpensive multimode pump laser, with which it is still possible to obtain continuously
tunable single-mode signal output. Cavity ringdown (CRD) spectroscopy also figures prominently, with infrared (IR) CRD spectra
from both grating-scanned and TDL-seeded OPOs reported. Finally, a tunable ultraviolet (UV) source, combining a TDL-seeded
passive-cavity OPO and a sum-frequency generation stage, is developed for measurements of time-resolved IR-UV double resonance
spectra of acetylene and UV laser-induced fluorescence spectra of nitric oxide.
Received: 28 March 2000 / Published online: 13 September 2000 相似文献
932.
Milnor link invariants and quantum 3-manifold invariants 总被引:1,自引:0,他引:1
Let be the 3-manifold invariant of Le, Murakami and Ohtsuki. We show that , where denotes terms of degree , if M is a homology 3-sphere obtained from by surgery on an n-component Brunnian link whose Milnor -invariants of length vanish.?We prove a realization theorem which is a partial converse to the above theorem.?Using the Milnor filtration on links,
we define a new bifiltration on the vector space with basis the set of oriented diffeomorphism classes of homology 3-spheres. This includes the Milnor level
2 filtration defined by Ohtsuki. We show that the Milnor level 2 and level 3 filtrations coincide after reindexing.
Received: October 23, 1998. 相似文献
933.
Natalya Fridman Moshe Kapon Menahem Kaftory 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(12):o685-o686
The molecules of 2‐chloro‐4,6‐dimethoxy‐1,3,5‐triazine, C5H6ClN3O2, lie on a crystallographic mirror plane. There is a close contact of 3.180 (3) Å between one of the methyl C atoms and the N atom of a neighboring molecule. Differential scanning calorimetry measurements show that methyl rearrangement does not take place in the solid state, despite the close proximity of the methyl group to the N atom. 相似文献
934.
Ariel Sluszny Michael S. Silverstein Shifi Kababya Asher Schmidt Moshe Narkis 《Journal of polymer science. Part A, Polymer chemistry》2001,39(1):8-22
Novel semi‐IPN (interpenetrating polymer networks) were synthesized through vinyl silane modification of unplasticized poly(vinyl chloride) (PVC) films using relatively low temperatures, relatively high vinyl silane contents, and several different processing routes. A free‐radical initiator was used to promote reaction of the vinyl groups, and an aqueous acetic acid solution was used to promote the methoxysilane hydrolysis and condensation (HC) reactions for siloxane crosslink formation. A gel consisting of silane alone was formed prior to the HC process, indicating the formation of a semi‐IPN. The gel content following the HC process far exceeded the silane content, indicating a significant amount of PVC was entrapped by the silane network. This conclusion is supported by the homogeneous molecular structure and morphology of the films. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 8–22, 2001 相似文献
935.
936.
Alexander Kamyshny Matti Ben‐Moshe Shai Aviezer Shlomo Magdassi 《Macromolecular rapid communications》2005,26(4):281-288
Summary: Two types of ink‐jet inks are presented: ink containing an aqueous dispersion of silver nanoparticles and an oil‐in‐water microemulsion‐based ink. The metallic ink contains nanoparticles of silver, which are formed in the presence of an ionic polymeric stabilizer. Sintering of the printed image obtained with the use of such silver‐based inks at temperatures as low as 300 °C results in formation of patterns possessing noticeable conductivity. The microemulsion inks are based on a thermodynamically stable microemulsion, in which the dispersed oil phase is a volatile solvent containing a water‐insoluble colorant. After contact of the jetted ink droplets with a substrate, nanodroplets of the microemulsion are converted into nanoparticles of the solubilized colorant. In some cases, it was found that the evaporation of microemulsion ink droplets leads to formation of rings composed of ordered nanoparticles.