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201.
In this paper we report a theoretical analysis of a long wavelength photoconductive detector for characterizing and optimizing
the device in respect of voltage responsivity, quantum efficiency, detectivity and noise equivalent power. The model has been
applied to examine the potential of an n-type Hg0.77Cd0.23Te photoconductive detector for possible application in free space optical communication system operating at the atmospheric
window near 9.6 μ m. In the present analysis we have taken into account all the major recombination mechanisms (e.g., Radiative,
Auger, and Shockley-Read-Hall types) including the effect of surface recombination at the interfaces that shape the characteristics
of photoconductor. The results obtained on the basis of our analysis reveal that in the absence of surface recombination the
device exhibits a peak quantum efficiency of 90%, a maximum detectivity of 108 MHz1/2/W at 77 K, a 3 dB bandwidth of 117.86 MHz and noise voltage of 5.4 × 10−6 V/Hz1/2. The sweep-out effect has been found to degrade the detectivity nearly by a factor of 10 at the same temperature and wavelength
of operation. The estimated noise equivalent power of the photodetector is of the order of 10−9 W at 9.6 μm wavelength. 相似文献
202.
The behaviour of ubiquitous radon (), thoron () and their progeny in the indoor atmosphere generally reflect a complex interplay between a number of processes, the most important of which are radioactive -decay, ventilation, attachment to aerosols and deposition on the surfaces. The present work involved a long-term (1997–2000) passive monitoring of and in the indoor environment of the North-Eastern region of India. This region being a zone of high seismicity, the indoor radon and thoron measurement of the region will provide a better insight and a valuable database for any study related to radon and thoron anomalies. 相似文献
203.
204.
K. K. Dwivedi 《Radiation measurements》1997,28(1-6):149-151
Chemical etching characteristics of mica, Lexan and cellulose acetate have been studied for fission fragment tracks. Under suitable etching conditions a few critical etching parameters for these three track detectors have been determined. An empirical relationship between complete etching time and the etching temperature has been established. 相似文献
205.
M. H. Key W. J. Blyth A. E. Dangor P. Dhez A. Djoui L. Dwivedi M. Holden P. B. Holden P. Jaegle C. L. S. Lewis A. G. McPhee A. Modena M. Nakai D. Neely P. A. Norreys A. A. Offenberger G. J. Pert J. A. Ploues S. G. Preston S. A. Ramsden S. J. Rose B. Russ C. G. Smith A. Sureau G. J. Tallents F. Walsh J. S. Wark Y. L. You J. Zhang 《Optical and Quantum Electronics》1996,28(3):201-208
Recent progress in the development of XUV lasers by research teams using high-power and ultrashort-pulse Nd: glass and KrF laser facilities at the Rutherford Appleton Laboratory is reviewed. Injector-amplifier operation and prepulse enhanced output of the Ge XXIII collisional laser driven by a kilojoule glass laser, enhanced gain in CVI recombination with picosecond CPA drive pulses from a glass laser, and optical field ionization and XUV harmonic generation with a KrF CPA laser are described. 相似文献
206.
The phenomenon of signature inversion in the doubly-odd nuclei152Eu and156Tb is understood within the framework of a two-quasiparticle plus rotor model. It is shown that theh
9/2:1/2[541] proton orbital plays a crucial role in reproducing this phenomenon. 相似文献
207.
The reinforcement of nano-barium titanate in ferrite filled poly-ether-ether-ketone (PEEK) composites caused a shift in the
decomposition temperature, at which maximum mass loss occurred, to higher side and enhancement in char yield in thermogravimetric
analysis. Loss tangent and glass transition temperature of ferrite filled PEEK composites were also found to be increased
with the reinforcement of nano barium titanate. The effect of nano barium titanate on the melting behaviour of ferrite filled
PEEK composites was negligible.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
208.
Palladium‐Catalyzed Regio‐ and Stereoselective Cross‐Addition of Terminal Alkynes to Ynol Ethers and Synthesis of 1,4‐Enyn‐3‐ones
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Madala Hari Babu Vikas Dwivedi Ruchir Kant Dr. Maddi Sridhar Reddy 《Angewandte Chemie (International ed. in English)》2015,54(12):3783-3786
Conjugated enynes, enol ethers, and enynones are versatile building blocks that can be elaborated by a wide variety of synthetic transformations. The selective synthesis of such units is a prerequisite for their effective utilization. The synthesis of conjugated 2‐phenoxyenynes through a palladium‐catalyzed cross‐addition of terminal alkynes to phenylethynyl ethers (hydroalkynylation) is now presented. The reaction is highly regio‐, stereo‐, and chemoselective, and shows excellent tolerance toward functional groups. The addition further features very mild reaction conditions (room temperature) and an inexpensive catalytic system (without a ligand and with a cheaply available Pd catalyst). The thus synthesized enynyl ethers with allylic hydroxy tethers, which survived the reaction, were shown to be ready precursors for valuable 1‐en‐4‐yn‐3‐ones. 相似文献
209.
210.