The 14N2/15N2 and 14N2/14N15N liquid-vapour isotope separation factor

A theoretical calculation of the ¹⁴N₂/¹⁵N₂ and ¹⁴N₂/¹⁴N¹⁵N liquid-vapour isotope separation factors using a diatomic, or atom-atom potential is undertaken. The results show that this potential is capable of representing the isotope separation factors with some permissible variation in the parameter set.     

Experimental transition probabilities in N III,N IV and N V spectra

We have obtained transition probabilities (Einstein's A values) of thirteen transitions in doubly (N III), six in triply (N IV) and two in four times (N V) ionized nitrogen spectra belonging to the 3s-3p and 3p-3d transitions using a relative line intensity ratio (RLIR) technique. The linear low-pressure pulsed arc was used as an optically thin plasma source operated at 51 400 K electron temperature and 2.2×10²³ m^-3 electron density in nitrogen plasma. Our A values are compared to recent theoretical and experimental data. Received 18 December 2001 / Received in final form 29 January 2002 Published online 28 June 2002     

(N, 2N) Correlation Theory

A semi-analytic theory of (N, 2N) reactions incorporating central, tensor, spin-orbit and quadratic spin-orbit components of the two-nucleon t-matrix is developed. Simplifications arise pom a suitable choice of scattering geometry and an asymmetric mode of energy sharing. Using modified plane waves for the continuum wave functions results in analytic expreasions for the volume integrals.     

N \bar N Annihilation creates two mesons

N \(\bar N\) annihilation is assumed to occur exclusively via two-meson production, with nearest threshold dominance. A phenomenological expression for the branching ratios, implementing the rule, contains two parameters. The set ofs- andp-wave (q \(\bar q\) ) mesons is used. Reasonable results are obtained for rates measured inp \(\bar p\) annihilation at rest. The numerous channels are projected into the multipion and kaon final states for comparison with in-flight experiments. A good overall agreement is reached up top _lab～3 GeV/c; beyond, more mesons should be included to provide new thresholds.     

Three-particle unitarized impulse approximation and d(N,2N)N reaction

The three-particle unitarized impulse approximation has been used for the investigation of the quasi-free knock-out d(N,2N)N reaction within the non-relativistic kinematic region. It is stated that in all cases when the conditions of the method applicability and the quasi-free kinematics are satisfied, the successful explanation of all available experimental data both on d(p,2p)n and d(p,pn)p reactions is ensured.     

N × N集成光开关阵列模型

报道了由2N个1 × N 多模干涉马赫-曾德尔光开关组成的N × N光开关阵列结构,分析了这种结构的开关阵列优势和局限性.用场传输矩阵方法建立了1 × N多模干涉光开关的光场传输方程.给出了光开关阵列从任一输入端输入、从任一输出端输出时阵列开关的工作条件.在上述原理及理论基础上分析了4×4光开关阵列的结构和工作条件.     

N\bar N annihilation into two body channels

A simple model is constructed forN¯N annihilations into two non-strange mesons. Determining the ratio of isospin one to isospin zero annihilation by experimental information we predict the branching ratios for these channels. The agreement with experiment is surprisingly good.     

Nα and N6Li microscopic potentials

The nucleon-alpha and nucleon-lithium potentials are generated from Green's density dependent effective nucleon-nucleon interaction using a microscopic model with antisymmetrization effects included. A phenomenological parametrization and the energy dependence of the potentials are derived.     

Introduction to Quantum Statistical Mechanics, 2nd edn., by N.N. Bogolubov and N.N. Bogolubov Jr

The mobility and self-diffusion of polymer molecules in concentrated systems or in the molten bulk state is largely controlled by entanglements between the molecules. These entanglements are a result of the chain-like nature of the molecules and of their extended, coil-like configuration. The conformation and mobility of polymer molecules in dilute solution—which are relatively well understood—are discussed; this leads to a consideration of self-diffusion in the more concentrated states and in the bulk polymer melt, and several special properties of polymers which are controlled and modified by the molecular self-diffusion are examined.

Our current theoretical understanding of polymeric self-diffusion in highly entangled systems is outlined, and the ways in which such diffusion may be studied experimentally are briefly described. The final part of the review describes a recent experimental study of self-diffusion in a polymer melt; the results of this study may provide new insight into the motion of entangled, chain-like molecules.     

Disintegration of Ar N,Kr N,and (N2) N clusters during collisions with highly vibrationally excited SF6 molecules

It is shown that, when highly vibrationally excited SF₆ molecules (with vibrational energy E _vib ≥ 0.5–2 eV) collide with weakly bound van der Waals Ar _N , Kr _N , or (N₂) _N (N ≤ 30–40 atoms in a cluster) clusters in intersecting molecular and cluster beams, the molecules are trapped by the clusters, the clusters then undergo full disintegration, and the trapped molecules become free. The method of studying this process and the results obtained are described. The possibilities of application of this method for selective doping of clusters by molecules, laser separation of isotopes, and selective transportation of molecules to a surface are discussed.     

The N4 molecule and the N3 + ion

The possibility of the nitrogen molecule forming a stable dimer is investigated. Through ab initio calculations in an extended contracted-gaussian basis, it is demonstrated that N₄ in tetrahedral geometry and N₃ ⁺ in D _3h geometry are local minimum points on their respective internuclear potential energy surfaces. The N₄ molecule is considerably higher in energy than two ground-state N₂ molecules and some study of the barrier for N₄ decomposition has been made. The bond lengths and force constants for the two systems are shown to be similar to their hydrocarbon counterparts, C₄H₄ and C₃H₃ ⁺, tetrahedrane and cyclopropenyl cation. Other related systems are discussed as well.     

C59N和C19N晶体的合成

通过溶解C60的CCl4溶液在大气中的慢蒸发可以合成C59N和C19N晶体,这项实验结果为CnN(n≤59)晶体研究开辟了一种简单而有效的途径.     

N\bar N annihilation at rest into five pions

annihilation at rest into five pions was studied in the ASTERIX spectrometer by stopping antiprotrons from LEAR in a H₂ or D₂ gas target. In annihilations in H₂ leading to the ^+–+–0 final state, the invariant mass spectra of two, three, and four pions show no evidence for any new narrow states. In the difference of the four pion mass spectra recoiling against a ^– and those recoiling against a ⁺ shows a resonance-like structure ( (1480)), confirming a previous analysis with a smaller event sample. The (1480) mass is shown to depend strongly on the momentum of the spectator proton. In H₂, we searched for the (1480) in the reaction (1480), (1480) ^+–+– to clarify whether the (1480) is identical to the 4-mode of thef ₂ (1520). No evidence for this decay mode was found. A prominent resonance in innihilation into five pions is the meson. We find two quasi-two-body intermediate states: and (1235). The mass and width of theb ₁ (1235) are determined to be:

Phases of resonant amplitudes: πN → ϱN

Using SU(6)_W symmetry in its l-broken form we find that the newly reported relative signs of πN → ?N resonant amplitudes seem to indicate a universal “SU (6)_W-like” preference for all observed multiplets. Since the corresponding πN → πΔ phases favour an “anti-SU(6)_W” solution for the 70, L^P = 1^? multiplet the l-broken SU (6)_W model now faces a serious contradiction.     

Recombination luminescences resulting from the photoionization of N,N, N′, N′-tetramethyl-p-phenylenediamine in the low temperature matrices. II

The delayed luminescences and thermal glow curves from ultraviolet-irradiated rigid solutions of N, N, N′, N′-tetramethyl-p-phenylenediamine (TMPD) were investigated. The luminescence which comprises the flourescence and phosphorescence of TMPD was affected by the composition of the matrix and an added electron trap, that is, benzene, diphenyl, carbon dioxide, oxygen, etc. It was found that the glow curves for systems containing these electron-trapping reagents show two components, which are concluded to be due, respectively, to electrons trapped by the solvent and these reagents. The electrons trapped by the solvent are released at the lower temperature. These results are indicative of the capabilities of these added molecules to capture electrons in the rigid organic matrices. It has also been found that the glow curve for a concentrated solution of TMPD shows two maxima, suggesting that TMPD itself acts as an electron trap. Oxygen quenches the delayed luminescence and thermoluminescence strongly. The intensity ratios between fluorescence and phosphorescence were measured and correlated with the glow curves.     

N,N,N,N-tetradentate Macrocyclic Ligand Based Selective Fluorescent Sensor for Zinc (II)

N,N,N,N-tetradentate macrocyclic ligand (L) has been synthesized by the condensation of benzil and semicarbazide and characterized. On excitation by light of wavelength 350?nm, L exhibited a fluorescent peak at λ(max)?=?454?nm, which showed ca 6 times enhancement in intensity with a blue shift on interaction with Zn(2+). L has been found to act as a selective fluorescent sensor for zinc(2+) ion over a host of other metal ions such as- Cd(2+), Pb(2+), Hg(2+), Ca(2+), Fe(2+), Na(2+), Co(2+), Mn(2+), Cu(2+) and Ni(2+), in 1:1 CH(3)OH:H(2)O. A 1:1 complex formation between L and Zn(2+) was proved. The enhancement in the fluorescence could be explained on the basis of Photo induced electron transfer (PET) mechanism with log β?=?1.86.     

Measurements of the 3ν 3 band of 14N15N16O and 15N14N16O using continuous-wave cavity ring-down spectroscopy

The absorption spectra of the 3ν₃ band of nitrous oxide isotopologues, ¹⁴N¹⁵N¹⁶O and ¹⁵N¹⁴N¹⁶O, have been measured using diode laser cavity ring-down spectroscopy in 6400–6463 and 6465–6532 cm^-1, respectively. Spectroscopic parameters and the rotational line intensities of the bands have been determined. We have applied this spectroscopic technique to the measurements of the absolute isotope ratio of those isotopologues using the absolute line intensities. PACS 32.10.Bi; 33.20.Vq; 33.70.-w; 42.55.Px; 42.62.Fi