Photochemical vapor deposition of amorphous silicon through 185 nm excitation of monosilane

Photochemical vapor deposition of a-Si films at a high rate using SiH₄ and a 185 nm low pressure mercury lamp is described. A maximum rate of 1 nm/sec was attained using the 185 nm lamp. This rate was about ten times higher than that using a 254 nm lamp. Assuming that there is no interaction between the effects of the two wavelengths, the deposition rate per light output power of 184.9 nm light is 160 times larger than that for 253.7 nm light. The absorption cross-section of the 184.9 nm light is ten times greater than that for the 253.7 nm light.     

Texture in the superconducting order parameter of CeCoIn5 revealed by nuclear magnetic resonance

We present a 115In NMR study of the quasi-two-dimensional heavy-fermion superconductor CeCoIn5 believed to host a Fulde-Ferrel-Larkin-Ovchinnikov (FFLO) state. In the vicinity of the upper critical field and with a magnetic field applied parallel to the ab plane, the NMR spectrum exhibits a dramatic change below T*(H) which well coincides with the position of reported anomalies in specific heat and ultrasound velocity. We argue that our results provide the first microscopic evidence for the occurrence of a spatially modulated superconducting order parameter expected in a FFLO state. The NMR spectrum also implies an anomalous electronic structure of vortex cores.     

1,8-bis(diphenylmethylium)naphthalenediyl dication as an organic oxidant: synthesis of benzidines via self-coupling of N,N-dialkylanilines

1,8-Bis(diphenylmethylium)naphthalenediyl dications promoted oxidative coupling of various N,N-dialkylanilines to afford the corresponding para-coupled bisanilines, benzidines, in good to excellent yield. The dications were readily prepared from a cyclic ether precursor, derived from 1,8-dibromonaphthalene, via deoxygenation with a silylating reagent in 1,1,1,3,3,3-hexafluoro-2-propanol under anhydrous conditions. [reaction: see text]     

Applicability of classical optical fiber theories to holey fibers

We discuss the applicability of well-established classical optical fiber theories to holey fibers. By appropriately defining the V parameter, we can easily estimate the fundamental properties of holey fibers, such as effective index, group-velocity dispersion, mode field diameter, beam divergence, and splice loss, through simple empirical expressions without the need for heavy numerical computations. We confirm the validity of the V parameter defined here by comparing the calculated results with the earlier experimental and numerical results.     

Lipase TL-mediated kinetic tesolution of 5-benzyloxy-1-tert-butyldimethylsilyloxy-2-pentanol at low temperature: concise asymmetric synthesis of both enantiomers of a piperazic acid derivative

Lipase TL-mediated kinetic resolution of (+/-)-5-benzyloxy-1-tert-butyldimethylsilyloxy-2-pentanol (5) at low temperature proceeded to give the corresponding (S)-alcohol 5 and (R)-acetate 6 in quantitative yields with high enantiomeric purity. The addition of bases such as pyridine, DMAP, 2,4- and 2,6-lutidines, or triethylamine considerably enhanced the rate of kinetic resolution. The alcohol (S)-5 and the acetate (R)-6 were converted to piperazic acid derivatives (R)- and (S)-3, respectively, via the intramolecular Mitsunobu reaction as a key step.     

Synthesis of conjugated enynes by assembly of three components, ketones, chloromethyl p-tolyl sulfoxide, and acetylenes, with the magnesium carbenoid 1,2-CC insertion as the key reaction

The reaction of 1-chlorovinyl p-tolyl sulfoxides, which were derived from ketones and chloromethyl p-tolyl sulfoxide, with lithium acetylides gave adducts in moderate to good yields. Treatment of the adducts with Grignard reagents resulted in the formation of magnesium carbenoids by the sulfoxide-magnesium exchange reaction. 1,2-Carbon-carbon insertion (1,2-CC insertion) reaction of the generated magnesium carbenoids took place to afford conjugated enynes in good to high yields. This procedure provides a good method for the synthesis of multi-substituted conjugated enynes.     

Si PIN X‐ray photon counter

A Si PIN detector for visible light detection, instead of a Geiger‐Müller tube, is applied to X‐ray photon counting. We counted radiation from a checking source of a Geiger‐Müller counter with a Si PIN counter and with a Geiger‐Müller counter. White X‐ray of energy up to 20 keV emitted from a pyroelectric X‐ray emitter was also counted, and the Si PIN X‐ray counter showed a similar curve of count rate versus source distance in both measurements. Pulse counting was performed by spectroscopy circuits. An audio digitizer with computer software for signal processing was also used to simplify the photon counter. A plot of count rate versus time was obtained with this setup. With simple pulse counting circuits, Si PIN X‐ray counters have advantages such as compact structure, low cost and easy application. Copyright © 2011 John Wiley & Sons, Ltd.     

Gas by-products of CF3I under AC partial discharge

This paper presents the decomposition by-products of trifluro-iodo-methane and their relative proportions in the gas phase under the occurrence of partial discharge. The experiment was performed in the presence of water vapor from 250 to 400 ppm under a non-uniform electric field configuration. The experimental results reveal that the by-products of C₂F₆, C₂F₄, C₂F₅I with the amount of 1300, 200, and 55 (CH₃I) ppm, respectively, were produced for a cumulative charge of 161 mC. Other by-products, such as C₃F₈, CHF₃, C₃F₆ CH₃I were obtained at less than 30 ppm C₂F₆ was the dominant gas by-product of trifluro-iodo-methane suffering partial discharge.