超高泵浦功率下的Xe(6p[1/2]0, 6p[3/2]2, 和6p[5/2]2)原子的能量转移过程

本文研究了Xe(6p[1/2]₀, 6p[3/2]₂, and 6p[5/2]₂)原子在聚焦条件下的动力学过程. 激发能级的原子密度在聚焦条件下会显著地增加,因此两个高激发态原子之间的energy-pooling碰撞的概率也会增加. 这种energy-pooling碰撞主要有三种类型. 第一种类型为energy-pooling碰撞导致的电离. 一旦将激发激光聚焦,就可以从侧面的窗口观察到非常明显的电离现象,不论激发能级是6p[1/2]₀、6p[3/2]₂或6p[5/2]₂能级. 这种电离的产生机理是energy-pooling电离或者一个Xe^*原子再吸收一个光子产生电离. 第二种类型为跨越较大能极差的energy-pooling碰撞. 当激发能级为6p[1/2]₀能级的情况下,两个6p[1/2]₀原子碰撞会产生一个5d[3/2]₁原子和一个6s''[1/2]₀原子. 第三种类型为跨越较小能级差的energy-pooling碰撞. 以5个二次产生的6p能级为上能级的荧光强度都变得更强,并且这些荧光的上升沿都变得更陡峭. 产生这些6p原子的主要机理是energy-pooling碰撞并非简单的碰撞弛豫. 基于理想气体原子之间的碰撞概率公式,推导出两个6p[1/2]₀原子的energy-pooling碰撞速率为6.39x10⁸s^-1. 此外,6s原子在聚焦条件下的密度也会增加. 因此所有的荧光曲线会因为辐射俘获效应而出现非常严重的拖尾.     

Structure Evolution in the Even-Even 124-134Xe with IBM2

We have investigated the structure evolution of the ^124-134Xe isotopic chain in the framework of the proton-neutron interacting model IBM2. The positive parity spectra of the ground state, quasi-β and quasi-γ bands are reproduced well. The staggering in ^124-130Xe are almost completely removed and the γ band agree well with the experiment data, even for the high-spin quasi-γ states. The key quantities of the collective structure evolution, including level energies, the B(E2) transition branching ratios, and the M1 excitations to 1₁⁺ mixer-symmetry states are analyzed by comparing with the experimental data. The parameters for representation of the O_πν(6) and SU_πν^*(3) features in isotopes are examined. Both experimental data and theoretical results show that the shape phase transition of ^124-134Xe isotopic chain is from the SU_πν^*(3) (triaxial rotation) to the U_πν(5) (vibration motion) with a considerable constituent of the O_πν(6) symmetry (γ-unstable rotation), where the shape phase transition rapidly takes place between the neutron number N = 76 and N = 78.     

ZSM-5 zeolite synthesis in the presence of a copper-phthalocyanine complex characterization by ESR and Xe NMR

In the presence of a copper phthalocyanine complex (CuPc), it is possible to synthesize ZSM-5 zeolite containing the complex, and the crystallinity is good, provided that the amount of CuPc trapped is lower than the number of channel intersections where it can be located without too much distortion. The crystallinity is retained after decomposition of the CuPc in a stream of air at 500 °C. The copper-ZSM-5 system is characterized by the combined application of xenon adsorption, ESR and ¹²⁹Xe NMR spectroscopy.     

Xenon porometry: a novel method for the derivation of pore size distributions

Xenon porometry is a novel method used for characterizing porous materials by the (129)Xe nuclear magnetic resonance of xenon gas. With the method, the diffusion of gas is slowed down by immersing the material in a medium, which can be in liquid or solid state during measurements. Because of slow diffusion, the signal of a xenon atom is characteristic of the properties of only one pore, and the composite signal of all atoms represents the distribution of properties. The method is especially applicable for determining pore size distribution because the chemical shifts of two different xenon signals (one from liquid and the other from gas pockets in solid) are dependent on pore size. Therefore, the shapes of these signals represent pore size distribution function. In addition, the porosity of the material can be determined by comparing the intensities of two signals. This article focuses on describing xenon signals observed from gas pockets in a solid medium, which has turned out to be most convenient for pore size determination.     

Nuclear spin resonance of (129)Xe doped with O(2)

Spin-lattice relaxation of (129)Xe nuclei in solid natural xenon has been investigated in detail over a large range of paramagnetic O(2) impurity concentrations. Direct measurements of the ground state magnetic properties of the O(2) are difficult because the ESR (electron spin resonance) lines of O(2) are rather unstructured, but NMR measurements in the liquid helium temperature region (1.4-4 K) are very sensitive to the effective magnetic moments associated with the spin 1 Zeeman levels of the O(2) molecules and to the O(2) magnetic relaxation. From these measurements, the value of the D[Sz(2)-(1/3)S(2)] spin-Hamiltonian term of the triplet spin ground state of O(2) can be determined. The temperature and magnetic field dependence of the measured paramagnetic O(2)-induced excess line width of the (129)Xe NMR signal agree well with the theoretical model with the spin-Hamiltonian D=0.19 meV (2.3 K), and with the reasonable assumption that the E[S(x)(2)-S(y)(2)] spin-Hamiltonian term is close to 0 meV. An anomalous temperature dependence between 1.4 K and 4.2K of the (129)Xe spin-lattice relaxation rate, T(1n)(-1)(T), is also accounted for by our model. Using an independent determination of the true O(2) concentration in the Xe-O(2) solid, the effective spin lattice relaxation time (which will be seen to be transition dependent) of the O(2) at 2.3 K and 0.96 T is determined to be approximately 1.4 x 10(-8)s. The experimental results, taken together with the relaxation model, suggest routes for bringing highly spin-polarized (129)Xe from the low temperature condensed phase to higher temperatures without excessive depolarization.     

The sublimation of argon, krypton, and xenon

In this paper, the sublimation pressure of Ar, Kr, and Xe are obtained as functions of temperature from an exactly integrated form of the Clapeyron equation. No fitting to experimental data of the equilibrium pressure has been necessary. The deviation plots of the sublimation pressure show that the results are satisfactory. The derived enthalpy of sublimation of the three rare gases from T = 0 K up to their respective triple point temperatures are asymmetric, distorted parabolas showing maxima for . The , which is a measure of the cohesion energy of the solid crystals, is easily calculated. A general equation has been obtained for as a function of temperature which also gives the enthalpies of sublimation of neon and radon. The (s + ? + g) triple point coordinates of Rn are reassessed.     

一种惰性气体回收器的研制

文中介绍了一种从空气中针对惰性气体氪和氙的回收纯化装置。包括回收纯化惰性气体氪和氙的方法选择、原理、流程介绍及设计计算,并根据原理流程及设计计算进行了设计选型和结构设计。     

ChemInform Abstract: Heptacoordination: Pentagonal Bipyramidal XeF+ 7 and TeF- 7 Ions.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

ChemInform Abstract: An ab initio Potential Energy Surface and Vibrational Energy Levels of HXeBr.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.