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991.
Takaaki Yamamoto Jibin Alex Abraham Shigeki Mori Motoki Toganoh Soji Shimizu Masatoshi Ishida Hiroyuki Furuta 《化学:亚洲杂志》2020,15(6):748-752
Incorporating tungsten into the N3 core of a N‐fused porphyrin (NFP; 1 ) affords high‐valent tungsten(VI)‐NFP complexes, WClO2‐1 and 21‐chlorinated WClO2‐3 . The X‐ray structure of WClO2‐1 reveals a distorted octahedral geometry with sitting atop metal coordination. The absorption spectrum of WClO2‐1 displays bathochromically shifted Q‐like bands beyond 1000 nm, indicating an inherently narrow HOMO‐LUMO energy gap. DFT calculations show that the degeneracy of the LUMO and LUMO+1 pair of 1 is significantly resolved by the tungsten(VI) coordination. Conclusively, magnetic circular dichroism (MCD) spectroscopy and cyclic voltammetry provide a rationale for the narrow HOMO‐LUMO energy gap in the “16‐electron” d0 tungsten(VI)‐NFP complexes. 相似文献
992.
Shigeki Kawai Hongqian Sang Lev Kantorovich Keisuke Takahashi Kyoko Nozaki Shingo Ito 《Angewandte Chemie (International ed. in English)》2020,59(27):10842-10847
Recent advances in scanning probe microscopy on surface enable not only direct observation of molecular structures but also local probe reactions, in which unstable short‐lived products have been synthesized and analyzed. Now, an endergonic reaction to synthesize a single Sondheimer–Wong diyne from 6,13‐dibromopentaleno[1,2‐b:4,5‐b′]dinaphthalene by local probe chemistry on a ultra‐thin film of NaCl formed on a Cu(111) surface at 4.3 K is presented. The structures of the precursor, two intermediates, and the final product were directly identified by the differential conductance imaging with a CO functionalized tip. DFT calculations revealed that the multiple‐step reaction, being endergonic overall, is facilitated by temporal charging and discharging of the molecule placed in the nanometric junction between the Cu tip and the Cu substrate underneath the ultra‐thin NaCl film. This local probe reaction expands possibilities to synthesize nanocarbon materials in a bottom‐up manner. 相似文献
993.
Time-resolved Fourier transform spectroscopy (TR-FTS) is reviewed, with emphasis on synchronous FTS using continuously scanning interferometers. By using a high-resolution Bruker IFS 120 HR, a TR-FTS method has been developed with the help of a microcontroller SX, where a maximum of 64 time-resolved data are recorded with a preset time interval in a single scan of the interferometer. The time resolution is 1 μs, limited by the response time of the detector system used. This method has been applied to a pulsed discharge in an Ar and H2 mixture to observe time profiles of ArH+ and ArH emission spectra. Electronic transitions of He2 have been observed in the infrared region with this method, and from the time profiles, He2 in Rydberg states with higher energy than the b3Π state is found to be produced efficiently in afterglow plasma. Fifteen bands in the 2300-8000 cm−1 region have been assigned by using previously reported data from the optical region. A new band from the 5f state has been assigned for the first time through the 5f-4d band in the 2600 cm−1 region. 相似文献
994.
Naoki Kondo Shigeki Kobayashi Hiroyuki Sakaki 《Physica E: Low-dimensional Systems and Nanostructures》2006,32(1-2):49
The self-organized crystal growth of semiconductor quantum rings has opened a new possibility to study and exploit optical transitions between ring-shaped quantum states. In such states, orbital angular momenta of particle envelope functions are well-defined. We investigate theoretically the intraband interlevel transitions between such states and examine the possibility of electrical multipole radiations (EMRs). Selections rules due to envelope function quantum numbers are deduced. To enhance the EMR efficiency, we propose a novel coupled dot–ring structure, by which the lowest allowed EMR can be selected and manipulated, allowing the efficient radiation of multipole photons. 相似文献
995.
996.
Ultra-fast optical signal processing is a promising technology for future photonic networks. This paper describes possible
applications of nonlinear fibers to optical signal processing. The third-order optical nonlinearities in a fiber are discussed
by analyzing the interaction of co-propagating optical waves. The properties of a nonlinear fiber are then considered in terms
of optimizing the dispersion for achieving phase matching and decreasing walk-off. A highly nonlinear fiber (HNLF) is a practical
candidate for an ultra-high-speed signal processor. Using HNLF, the following experiments are successfully demonstated: ultra-broadband
wavelength conversion/optical phase conjugation by four-wave mixing, 160 Gb/s optical 3R-regeneration, and optical switching
up to 640 Gb/s using a parametric amplified fiber switch. Steps for further improvements are also discussed. 相似文献
997.
998.
The GaCl3-catalyzed reaction of allyltrimethylsilane and aldimines gave tetrahydroquinolines in good yields. Similarly, 4-methylquinoline was obtained by using trimethyl(propargyl)silane via a dehydrogenation process. 相似文献
999.
1000.
Parallel Microoptics for Interconnections Based on Vertical Cavity Surface Emitting Lasers Arrays 总被引:1,自引:0,他引:1
Shigeru Kawai 《Optical Review》2003,10(4):303-306
Low-cost vertical cavity surface emitting lasers (VCSELs) may allow the development of broadband optical networks. Designs suitable for microoptics and “jisso” (a Japanese terms which includes alignment, assembly, mounting and packaging) technologies are required for low-cost and small interconnection modules. Optical interconnections based on VCSEL arrays including both space and wavelength division multiplexing technologies are described. 相似文献