Wigner function of coherent state of N components

In this paper, we study the Wigner function of coherent state of N components, especially two components and three components. This function consists of two terms： the Gaussian term and the interference term with the negativity. The first term comprises N Gaussian surfaces evenly centred on a circle of radius ｜β｜ = ｜α｜ with a separate angle of 2π/N, and the second term is composed of 1/2N（N - 1） Gaussian-cosine surfaces evenly centred in a circular region of radius ｜β｜ 〈 ｜α｜. Here, a is the eigenvalue of the annihilation operator α, and β is a variable in some complex space in which the Wigner function is defined. We have proved that the essential condition to eliminate the negativity of the Wigner function is that the mean photon count of the coherent state is equal to that of the Glouber coherent state.     

Infrared Spectroscopic Study of N,N‐Dimethylthioformamide Complexes of the Hofmann Type

Four new Hofmanntype complexes, M(DMTF)₂Ni(CN)₄, (where DMTF is dimethylthioformamide, M=Mn, Cd, Co, or Ni) were synthesized and their structure was determined by an elemental analysis and infrared spectroscopy. The IR spectra of DMTF and its nickel tetracyanine complexes with Mn(II), Cd(II), Co(II), and Ni(II) have been investigated within the range 4000–400 cm^–1. The frequency shifts in the metal complexes agree with the assignment of the CS and CN frequencies. The complexes consist of infinite planar polymer layers of |MNi(CN)₄|. Ndimethylthioformamide is coordinated to this layer from above and below; it is a monodentate ligand and is Sbonded through the metal atom in these complexes.     

Photoproduction of baryons decaying into Nπ and Nη

A combined analysis of photoproduction data on γp↦ πN, ηN was performed including the data on KΛ and KΣ. The data are interpreted in an isobar model with s-channel baryon resonances and π, ρ (ω), K, and K ^* exchange in the t-channel. Three baryon resonances have a substantial coupling to ηN, the well-known N(1535)S ₁₁, N(1720)P ₁₃, and N(2070)D ₁₅. The inclusion of data with open strangeness reveals evidence for further new resonances, N(1840)P ₁₁, N(1875)D ₁₃ and, with weaker evidence, for N(2170)D ₁₃.     

PS-1 Optical Interconnection of 2N×2N Using N×N Holographic Lens Array

A method of N×N sub-array crisscross insertion has been put forward. N×N holographic lens array is used for realizing PS-1 optical interconnection of the 2N×2N element array. The condition for the sub-array interlacing was analyzed. The formula of the PS-1 imaging magnifying power and the imaging distance have been given for both parallel light illumination and divergent light illumination. The results indicated that the formula of the PS-1 imaging magnifying power and imaging distance realized by N×N sub-array crisscross insertion are identical with the results of the PS realized by 2×2 holographic lens array. The experiments prove correctness of the formula.     

Chemical Synthesis of C3N and BC2N Compounds

A chemical reaction for the preparation of B-C-N compounds by using carbon tetrachloride （CC14）, boron tribromide （BBr3）, lithium nitride （Li3N） and sodium as reactants has been carried out at the temperature of 400℃. Measurements of FTIR, XRD, TEM and EELS show that two kinds of compounds have been formed in the prepared sample. One is hollow sphere-like C-N with an amorphous, structure; the other is piece-like polycrystalline B-C-N with the hexagonal structure. Their determined compositions are close to C3N and BC2N, respectively.     

Theoretical Analysis of Structures of Ga4N4 Clusters

The structures and energies of a Ga4N4 cluster have been calculated using a full-potential linear-muffin-tin-orbital molecular-dynamics (FP-LMTO MD) method. We obtained twenty-four structures for a Ga4N4 cluster. The most stable structure we obtained is a C8 three-dimensional structure, the energy of which is lower than that of the C2v symmetry structure proposed by Kandalam et al. [J. Phys. Chem. B106 (2002) 1945] The calculated results show that the isomer with an N3 subunit is preferred, supporting the previous result made by Kandalam et al,We found that the most stable structure of Ga4N4 clusters presented semiconductor-like properties through the calculation of the density of states.     

Decay properties of N ≃ Z nuclei

This review focusses on recent results obtained by using fusion-evaporation reactions for the production of N ≃ Z nuclei, the on-line mass separator of GSI for the preparation of the radioactive samples, and charged-particle and γ-ray detectors for performing decay spectroscopy. The experimental results on prompt and β-delayed disintegration modes are discussed in comparison with theoretical model predictions. Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002 RID="a" ID="a"e-mail: e.roeckl@gsi.de     

Fluorescence of N,N′-dimethylaminobenzonitrile in polyvinyl alcohol stretched films

We have demonstrated that the conditions of the charge-transfer (CT) reaction in the N,N′-dimethylaminobenzonitrile (DMABN) molecule in polyvinyl alcohol (PVA) polymer matrices can be considerably changed upon their stretching deformation. The fluorescence spectrum of DMABN in PVA has two characteristic bands in the ultraviolet (UV) and visible spectral ranges, which indicates that a CT reaction proceeds in the excited state. Stretching leads to a strong decrease in the intensity of the UV band, the contribution of which in undeformed samples is comparable with the emission in the violet range. Even single stretching PVA films strongly reduces the emission intensity of the UV band, with this effect being dramatically enhanced upon sixfold stretching. In the latter case, The fluorescence spectrum is characterized by a strong CT band, the relative intensity of which is 3.5 times higher than even in a strongly polar aprotic solvent, such as acetonitrile. The obtained data indicate that, as a result of mechanical stretching, it becomes possible to change basic intermolecular factors that affect the CT rate in PVA samples.     

PS~(-1) Optical Interconnection of 2N×2N Using N×N Holographic Lens Array

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Vibrational Spectroscopic and Theoretical Studies of Urea Derivatives with Biochemical Interest: N,N′-Dimethylurea,N,N,N′,N′-Tetramethylurea,and N,N′-Dimethylpropyleneurea

Abstract

Mid-infrared, far-infrared, and Raman vibrational spectroscopic studies were combined with density functional theory (DFT) calculations and normal coordinate force field analyses for N,N′-dimethylurea (DMU), N,N,N′,N′-tetramethylurea (TMU), and N,N′-dimethylpropyleneurea (DMPU: IUPAC name 1,3-dimethyltetrahydropyrimidin-2(1H)-one). The equilibrium molecular geometry of DMU (all three conformers), TMU, and DMPU and the frequencies, intensities, and depolarization ratios of their fundamental infrared (IR) and Raman vibrational transitions were obtained by DFT calculations. The vibrational spectra were fully analyzed by normal coordinate methods as well. A starting force field for DMPU was obtained by adapting corresponding force constants for DMU and TMU, resulting after refinements in the stretching force constants C=O (7.69, 7.30, 7.68 N·cm^?1), C–N (5.16, 5.55, 5.05 N·cm^?1), and C-Me (5.93, 4.00, 4.22 N·cm^?1) for DMU, TMU, and DMPU, respectively. The dominating conformer of liquid DMU was identified as trans-trans, strong intermolecular hydrogen bonding was verified in solid DMU, and weak dipole–dipole association was found in liquid TMU and in DMPU. Special attention was paid to analyzing the methyl group frequencies, which revealed deviations from local C_3v symmetry. A linear correlation was found between the CH stretching force constants and the inverse of the CH bond lengths (1/r ²). The averaged NH stretching frequencies of gaseous, dissolved, and solid urea and of DMU, with variations for hydrogen bonding of different strength, are linearly correlated to the NH stretching force constants. Characteristic skeletal vibrations were assigned for a broad variety of urea derivatives and also for pyrimidine derivatives, which all contain the N₂C=O entity. The very strong IR bands of C=O stretching (1,676 ± 40 cm^?1) and asymmetric CN₂ stretching (1,478 ± 60 cm^?1), and the very intense Raman feature of symmetric CN₂ stretching or ring breathing (757 ± 80 cm^?1), can be recognized as fingerprint bands also for the pyrimidine derivatives cytosine, thymine, and uracil, which all are nucleobases in DNA and RNA nucleotides.     

Effects of long-wavelength fluorescence excitation in N, N′-dimethylaminobenzonitrile liquid solutions

We have studied the properties of the emission, absorption, and excitation of dual fluorescence of N,N??-dimethylaminobenzonitrile in a set of solvents of different polarity under selective irradiation of solutions by light with different energies of quanta in the range of the long-wavelength absorption band. In all cases, dual fluorescence is observed, which is caused by emission from locally excited Franck-Condon and charge-transfer states. A change in the energy of excitation quanta has no effect on the position of the fluorescence bands; however, the intensity ratio between the bands noticeably changes in favor of the intensity of the long-wavelength band, which belongs to the charge-transfer state. To explain the observed effects, we involve data of quantum-mechanical calculations, which show that there is a considerable probability of occurrence in solutions of these systems of rotational isomers that differ in the orientation of the dimethylamino group with respect to benzonitrile. In the excited state, these rotamers have different charge-transfer reaction rates, which leads to a change in the intensity ratio of the observed fluorescence bands upon using the selective excitation.     

Analyticity of solutions of theO(N) nonlinear σ-model

We consider continuous weak solutions of the Euler-Lagrange equation associated with the Euclideand-dimensionalO(N) nonlinear -model. We show for arbitraryN and arbitraryd that such solutions with locally square integrable gradient are real analytic.     

Theoretical calculations of N2-broadened half-widths of ν5 transitions of HNO3

A number of satellite instruments are measuring nitric acid, HNO₃, in the Earth's atmosphere. In order to do retrievals of temperature and concentration profiles, the spectral parameters for many thousands of HNO₃ transitions must be known. Currently the HITRAN database uses a constant estimated value for the air-broadened half-width of HNO₃. To help improve the line shape parameters, complex Robert–Bonamy calculations were made to determine N₂-broadened half-widths for some 5000 transitions of HNO₃ in the ν₅ band. The intermolecular potential is a sum of electrostatic terms (dipole–quadrupole and quadrupole–quadrupole) and the atom–atom potential expanded to eighth order. The trajectory parameters were adjusted to yield better agreement with measurement. Velocity integrated calculations were made at seven temperatures in order to determine the temperature dependence of the half-widths. The half-width data are compared with available rotation band measurements. The average percent difference between the measured and calculated half-widths is ?2.38 for N₂-broadening and ?0.65 for air-broadening. The temperature, vibrational, and rotational state dependence of the half-width are investigated.     

Reaction Rate of Radiative р13N Capture

Russian Physics Journal - Within the framework of the modified potential cluster model with forbidden states, we have considered the astrophysical S-factor of radiative р13N capture at low...     

Transport properties of H–N2 mixtures

Transport coefficients (shear viscosity, volume viscosity, thermal conductivity, and mass and thermal diffusion coefficients) of H–N₂ mixtures in the dilute-gas limit have been calculated from the intermolecular potential in the temperature range 300–2000K using the classical trajectory method. The intermediate results pertaining to H–N₂ binary interactions are reported, mainly in terms of cross-section ratios. Cross-sections evaluated with the Mason–Monchick approximation yield very good results for this system, the largest deviations, about 2.5%, being observed for the thermal diffusion coefficient. The accuracy here of this approximation can primarily be attributed to a light H atom and a weakly non-spherical potential resulting in a high rotational collision number. Furthermore, we investigate to which H–N₂ cross-sections and their ratios the values of the mixture transport coefficients are most sensitive. Our results indicate that, for some cross-section ratios, reliance on universal correlations at high temperatures, often used in flame codes, can induce sizeable errors in the thermal conductivity coefficient and especially in the thermal diffusion coefficients. We also observed that the volume viscosity is particularly sensitive to the value of the cross-section for internal energy relaxation in H–N₂ collisions.     

Néel temperature of quasi-low-dimensional Heisenberg antiferromagnets

The Néel temperature T(N) of quasi-one- and quasi-two-dimensional antiferromagnetic Heisenberg models on a cubic lattice is calculated by Monte Carlo simulations as a function of interchain (interlayer) to intrachain (intralayer) coupling J(')/J down to J(')/J approximately = 10(-3). We find that T(N) obeys a modified random-phase approximationlike relation for small J(')/J with an effective universal renormalized coordination number, independent of the size of the spin. Empirical formulas describing T(N) for a wide range of J(') and useful for the analysis of experimental measurements are presented.     

Structures of NΩ and △Ω Dibaryons

We study the structures of NΩ and △Ω systems in the extended chiral SU（3） quark model by solving a resonating group method equation. The results show that both systems are weakly bound states and changed into unbound states if we consider the mixing of scalar mesons.