排序方式: 共有28条查询结果,搜索用时 171 毫秒
1.
B. M. Azizur Rahman A. K. M. Saiful Kabir Muttukrishnan Rajarajan Kenneth T. V. Grattan 《Optical and Quantum Electronics》2005,37(1-3):171-183
Modal solutions of planar photonic crystal waveguides with rectangular air-holes are presented by using a rigorous full-vectorial finite element-based approach. The effective indices, mode field profiles, spot-sizes, power confinements, modal hybridness, beat lengths and group velocity dispersions are shown for the fundamental and higher order modes of the quasi-TE and TM polarizations. 相似文献
2.
3.
Subashchandrabose S Saleem H Erdogdu Y Rajarajan G Thanikachalam V 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,82(1):260-269
FT-Raman and FT-IR spectra were recorded for 3-pentyl-2,6-diphenylpiperidin-4-one (PDPO) sample in solid state. The equilibrium geometries, harmonic vibrational frequencies, infrared and the Raman scattering intensities were computed using DFT/6-31G(d,p) level. Results obtained at this level of theory were used for a detailed interpretation of the infrared and Raman spectra, based on the total energy distribution (TED) of the normal modes. Molecular parameters such as bond lengths, bond angles and dihedral angles were calculated and compared with X-ray diffraction data. This comparison was good agreement. The intra-molecular charge transfer was calculated by means of natural bond orbital analysis (NBO). Hyperconjugative interaction energy was more during the π–π* transition. Energy gap of the molecule was found using HOMO and LUMO calculation, hence the less band gap, which seems to be more stable. Atomic charges of the carbon, nitrogen and oxygen were calculated using same level of calculation. 相似文献
4.
Govindasamy Rajarajan Natesan Jayachandramani Subramaniyan Manivarman Jayaraman Jayabharathi Venugopal Thanikachalam 《Transition Metal Chemistry》2008,33(3):393-397
The kinetics of oxidation of aldonitrones by 4-(dimethylamino)pyridinium chlorochromate (DMAPCC) has been studied in aqueous
N,N-dimethylformamide in the presence of perchloric acid. The reaction follows first-order kinetics with respect to each of DMAPCC
and nitrone. The order with respect to [H+] was found to be close to zero. The rate of oxidation was unaltered by the variation of [NaClO4] but addition of MnSO4 decreased the rate. The reaction rate was found to decrease with a decrease in dielectric constant of the medium. Electron-releasing
and electron-withdrawing groups perturb the reaction rate with a good Hammett correlation. The oxidation products were found
to be benzaldehyde and nitrosobenzene. The reaction was carried out at four different temperatures and the activation parameters
have been calculated. On the basis of the experimental findings, a suitable mechanism has been proposed. 相似文献
5.
Venkatachalam Rajarajan Balaji Mahalingam Murugan Savarimuthu Robinson Rangaswamy Nakkeeran 《Optical and Quantum Electronics》2017,49(5):198
In this paper, two dimensional photonic crystal, based eight-channel demultiplexer is proposed and designed for DWDM applications. The performance parameters of the demultiplexer such as transmission efficiency, channel spacing, spectral line width, Q factor, and crosstalk have been evaluated. The proposed demultiplexer comprises of bus waveguide, drop waveguide and parellogram resonant cavity (PRC). The bus waveguide transmits light to the PRC and exits through respective drop waveguide. The PRC consists of a parellogram resonator with a nano ring cavity that is used for dropping eight specific wavelength for ITU-T G 694.1 standard with 50 GHz channel spacing. The circular ring resonator is placed above the PRC wherein a resonant air hole (Cr) is positioned for desired channel selection. The channel selection is done by altering the radius of the air hole. In addition, a conjugate radiant neural network is implemented for optimizing the radii of resonant air holes to select the required channel wavelength. The proposed device is very compact and it could be considered for implementing the photonic integrated circuits. 相似文献
6.
S K Gupta V R Katti D P Gandhi S C Gadkari S C Sabharwal K K Gupta A K Rajarajan L C Gupta R Vijayaraghavan 《Pramana》1988,30(4):L341-L344
The results of our initial efforts to deposit thin films of YBa2Cu3O7−x
system on sapphire substrate are described. The deposited films are shiny black in appearance and are of quite uniform chemical
composition. The annealed films exhibit zero resistance superconducting transition temperatureT
c(R=0) ranging between 23 K and 30 K. 相似文献
7.
M. Sudha S. Senthilkumar R. Hariharan A. Suganthi M. Rajarajan 《Journal of Sol-Gel Science and Technology》2012,61(1):14-22
Nanoparticles of uncapped and PVA (poly vinyl alcohol) capped zinc oxide were synthesized by precipitation method. The synthesized
ZnO nanoparticles were characterized by fourier transform infrared spectroscopy, X-ray powder diffraction, scanning electron
microscopy, transmission electron microscopy and thermogravimetric-differential thermal analysis. The photocatalytic activity
of bare and modified ZnO nanoparticles was studied by monitoring the degradation of Rhodamine B. The results show that PVA
capped ZnO nanoparticles has reduced photocatalytic activity than the bare ZnO nanoparticles. The reduction in the chemical
oxygen demand and total organic carbon results also revealed the reduced photocatalytic activity of PVA capped ZnO. The UV-shielding
property was evaluated by measuring the transmittance which shows that both bare and PVA capped ZnO nanoparticles possess
good UV-shielding ability. 相似文献
8.
K. Rajarajan I. Vetha Potheher M. Vimalan J. Madhavan 《Journal of Physics and Chemistry of Solids》2007,68(12):2370-2375
Single crystals of tetrathiourea mercury(II) tetrathiocyanato manganate(II); Hg(N2H4CS)4Mn(SCN)4, (TMTM) were grown by slow solvent evaporation technique. The grown crystals were confirmed by single crystal and powder X-ray diffraction analysis. The optical absorption spectrum of TMTM in a mixed solvent of acetone and water shows the near ultra-violet cut-off wavelength corresponding to the absorption maximum as 335 nm. FT-IR spectrum identifies the characteristic absorption bands of thiourea and thiocyanate in both middle and far infrared regions, which further confirm the incorporation of both the ligands in the resulting compound. The electron spin resonance spectrum of TMTM was recorded both at room temperature and −196 °C, which reveals that the Mn environment is symmetrical with respect to the NCS ligand distribution. It is also interesting to note that there is no hyperfine coupling between Mn nucleus and its free electrons at both room temperature and −196 °C. The dielectric constant as well as dielectric loss of the sample were calculated for varying frequencies under different temperatures. 相似文献
9.
T. Jayanalina G. Rajarajan S. Parthiban S. C. Mojumdar 《Journal of Thermal Analysis and Calorimetry》2013,112(2):1025-1030
The 1:1 adduct of l-Alanine and sodium bromide (l-ANaBr) crystal has been grown from aqueous solution by a slow evaporation technique. l-alanine and sodium bromide were used in the ratio 1:1 for synthesis. Characterizations were carried out to study the thermal, optical, and mechanical properties of the grown crystal. Single-crystal X- ray diffraction analysis shows that the grown crystal belongs to the monoclinic system. The crystalline nature and its various planes of reflections were observed by powder XRD analysis. Thermal studies reveal that the crystal is stable up to 113.37 °C. The chemical compositions of the grown crystal were determined by FT-IR spectral analysis. The transmittance, absorption, and reflection spectrum of l-ANaBr crystal studied using a UV–Vis spectrometer indicates that the crystal has good optical transparency. The mechanical property of the grown crystal studied using Vickers microhardness measurement reveals that the crystal is a soft material. 相似文献
10.
ac Conductivity measurements are carried out across the metal to insulator transition in NiAl0.7Cr0.7Fe0.6O4. The low frequency data is analyzed using Summerfield scaling theory for hopping conductivity. The exponent of the scaling
behavior has significantly different values in the conducting and insulating regimes. The hopping frequency and the zero frequency
conductivity are found to increase with temperature, slowly in the metallic regime and rapidly in the insulating regime. 相似文献