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61.
The Squeezing and sub-poissonian photon statistics of an optical field are a purely quantum mechanical phenomenon and has
been accepted as means of achieving noise below the quantum shot-noise limit. The effect of higher-order squeezing and sub-poissonian
nature of an optical field in coherent anti-Stokes Raman scattering (CARS) and coherent anti-Stokes hyper Raman scattering
(CAHRS) are investigated under short-time approximation. The coupled Heisenberg equations of motion involving real and imaginary
parts of the quadrature operators are established and solved under short-time scale. The dependence of squeezing on the number
of photons is also investigated. It is also shown that higher-order squeezing allows a much larger fractional noise reduction
than lower-order squeezing. The occurrence of amplitude squeezing effects of the radiation field in the fundamental mode is
investigated in both the processes. The present work shows that squeezing is greater in CAHRS than the corresponding squeezing
in CARS. It is also shown that squeezing is greater in stimulated process than corresponding squeezing in spontaneous interaction.
The conditions for obtaining maximum and minimum squeezing are obtained. The photon statistics of the pump mode in the processes
has also been investigated and found to be sub-poissonian in nature. 相似文献
62.
The isotropic oscillator on a plane is discussed where the coordinate and momentum space are both considered to be non-commutative.
We also discuss the symmetry properties of the oscillator for three separate cases when the non-commutative parameters Θ and
for x and p-space, respectively, satisfy specific relations. We compare the Landau problem with the isotropic oscillator on non-commutative
space and obtain a relation between the two non-commutative parameters and the magnetic field of the Landau problem. 相似文献
63.
Pulak Ranjan Giri 《International Journal of Theoretical Physics》2008,47(10):2583-2590
We argue that it is possible to bind neutral atom (NA) to the ferromagnetic wire (FW) by inequivalent quantization of the
Hamiltonian. We follow the well known von Neumann’s method of self-adjoint extensions (SAE) to get this inequivalent quantization,
which is characterized by a parameter Σ∈ℝ(mod2π). There exists a single bound state for the coupling constant η
2∈[0,1). Although this bound state should not occur due to the existence of classical scale symmetry in the problem. But since
quantization procedure breaks this classical symmetry, bound state comes out as a scale in the problem leading to scaling
anomaly. We also discuss the strong coupling region η
2<0, which supports bound state making the problem re-normalizable. 相似文献
64.
Neeraj Kumar Giri 《Optics Communications》2008,281(13):3547-3552
Upconversion emission and energy transfer processes in singly, doubly and triply doped tellurite glasses have been studied under 798 and 980 nm laser excitations. Emissions have been observed at 482, 544, 584, 655 nm and at 477, 655, 698, 800 nm corresponding to Tb3+: 5D4 → 7F6, 7F5, 7F4, 7FJ (J = 0, 1, 2, 3) and Tm3+: 1G4 → 3H6, 1G4 → 3F4, 3F3 → 3H6, 3H4 → 3H6 transitions, respectively. Among Tm3+, Yb3+and Tb3+ ions only Tm3+ has a ground state absorption at 798 nm excitation due to 3H4 ← 3H6 transition. For 980 nm excitation only Yb3+ can absorb the incident radiation. However, for both types of excitations, emission from all the three ions Tb, Yb and Tm has been observed. Possible mechanisms are proposed as follows: under 798 nm excitation Tm3+ ions are excited which excite Yb3+ ions through energy transfer. Finally “cooperative energy transfer” from a pair of Yb3+ ions to Tm3+ and Tb3+ ions takes place. Under 980 nm excitation Yb3+ ions absorb the incident energy and excite Tm3+ and Tb3+ ions via cooperative energy transfer. Variation of emission intensity with the ion concentrations of Yb3+, Tm3+ and Tb3+ has been studied. The lifetime of the 1G4 level has also been measured. 相似文献
65.
Jyotsnendu Giri Pallab Pradhan Vaibhav Somani Hitesh Chelawat Shreerang Chhatre Rinti Banerjee Dhirendra Bahadur 《Journal of magnetism and magnetic materials》2008
Nanomagnetic particles have great potential in the biomedical applications like MRI contrast enhancement, magnetic separation, targeting delivery and hyperthermia. In this paper, we have explored the possibility of biomedical applications of [Fe1−xBxFe2O4, B=Mn, Co] ferrite. Superparamagnetic particles of substituted ferrites [Fe1−xBxFe2O4, B=Mn, Co (x=0–1)] and their fatty acid coated water base ferrofluids have been successfully prepared by co-precipitation technique using NH4OH/TMAH (Tetramethylammonium hydroxide) as base. In vitro cytocompatibility study of different magnetic fluids was done using HeLa (human cervical carcinoma) cell lines. Co2+-substituted ferrite systems (e.g. CoFe2O4) is more toxic than Mn2+-substituted ferrite systems (e.g. MnFe2O4, Fe0.6Mn0.4Fe2O4). The later is as cytocompatible as Fe3O4. Thus, Fe1−xMnxFe2O4 could be useful in biomedical applications like MRI contrast agent and hyperthermia treatment of cancer. 相似文献
66.
67.
Kriti Pathak Sourav Gayen Suvam Saha Chandan Nandi Shivankan Mishra Prof. Dr. Sundargopal Ghosh 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(18):e202104393
Treatment of [Cp*RuCl2]2, 1 , [(COD)IrCl]2, 2 or [(p-cymene)RuCl2]2, 3 (Cp*=η5-C5Me5, COD= 1,5-cyclooctadiene and p-cymene=η6-iPrC6H4Me) with heterocyclic borate ligands [Na[(H3B)L], L1 and L2 ( L1 : L=amt, L2 : L=mp; amt=2-amino-5-mercapto-1,3,4-thiadiazole, mp=2-mercaptopyridine) led to the formation of borate complexes having uncommon coordination. For example, complexes 1 and 2 on reaction with L1 and L2 afforded dihydridoborate species [LAM(μ-H)2BHL] 4 – 6 ( 4 : LA=Cp*, M=Ru, L=amt; 5 : LA=Cp*, M=Ru, L=mp; 6 : LA=COD, M=Ir, L=mp). On the other hand, treatment of 3 with L2 yielded cis- and trans-bis(dihydridoborate) species, [Ru{(μ-H)2BH(mp)}2], cis- 7 and trans- 7 . The isolation and structural characterization of fac- and mer-[Ru{(μ-H)2BH(mp)}{(μ-H)BH(mp)2}], 8 from the same reaction offered an insight into the behaviour of these dihydridoborate species in solution. Fascinatingly, despite having reduced natural charges on Ru centres both at cis-and trans- 7 , they underwent hydroboration reaction with alkynes that yielded both Markovnikov and anti-Markovnikov addition products, 10 a – d . 相似文献
68.
69.
Bhardwaj Hema Singh Chandan Kotnala R. K. Sumana Gajjala 《Analytical and bioanalytical chemistry》2018,410(28):7313-7323
Analytical and Bioanalytical Chemistry - Due to the similar electrochemical properties to graphene oxide (GO), graphene quantum dots (GQDs) are considered as a highly potential candidate for... 相似文献
70.
Dey S Pal C Nandi D Giri VS Zaidlewicz M Krzeminski M Smentek L Hess BA Gawronski J Kwit M Babu NJ Nangia A Jaisankar P 《Organic letters》2008,10(7):1373-1376
3,3'-Bipyrroles 3 could be synthesized using a double Michael addition reaction involving diaroyl acetylene 1 and the appropriate 1,3-dicarbonyls 2 using ammonium acetate as a nitrogen source. The axial chirality of bipyrrole was anticipated from the X-ray crystal structure and DFT calculations and confirmed by separating the racemates on a chiral column and subsequent CD spectra of the enantiomers. The absolute configuration of the enantiomers was achieved by theoretical CD spectra calculation using the ZINDO method. 相似文献