A 7.3 ms isomer of 161Lu

An isomer of ¹⁶¹Lu with a half-life of 7.3 ± 0.4 ms has been discovered in the heavy-ion reaction ¹⁴⁸Sm(¹⁹F, 6n)^161mLu. Oneγ-ray transition with energy 135.8 ± 0.2 keV was observed, and a K-conversion coefficient of 1.1 ± 0.3 deduced in the decay of this isomer.     

Levels of 234U and 236U excited by the (d,d') reaction

The energy levels of ²³⁴U and ²³⁶U have been studied through the inelastic scattering of 16 MeV douterons. A magnetic spectrograph was used to momentum-analyse the scattered deuterons at θ = 90° and 125°. Excited in both ²³⁴U and ²³⁶U were the ground state bands up to and including the 8⁺ members, the K^π = 0⁺β-vibrations, the K^π = 2⁺γ-vibrations, and the K^π = 0^? octupole vibrational bands. In ²³⁴U, additional levels at 1023 and 1126 keV are ascribed to a K^π = 2^? band, levels at 1238, 1312, and 1446 keV are identified as members of either a K^π = 0^? or 1^? configuration, and other tentative assignments are made for members of K^π = 1^? and 3^? configurations. Relative reduced transition probabilities, B(E2), to the 2⁺ rotational and γ-vibrational states are generally found to be in good agreement with Coulomb excitation measurements. Relative B(E3) values for the 3^? states excited are slightly higher than the predictions of a microscopic theory of octupole vibrations.     

Experimental investigation of deuteron photodisintegration in the δ-resonance region

Differential cross sections for the deuteron photodisintegration process were measured for photon energies between 200 and 440 MeV using the tagged photon beam facility of the Bonn 500 MeV synchrotron. At eight angles between 18° and 145° charged particles were detected simultaneously in time-of-flight spectrometers consisting of scintillation counters. Above the resonance region the measured cross sections agree fairly well with earlier results, whereas there are larger discrepancies at low photon energies.     

1,1-二甲基-2-(9-菲基)-环丙烷的直接同面1,3氢迁移

二甲基被氘代的标题环丙烷光解生成2-甲基d3-4-(9-菲基)-1-丁烯-d3,它的结构系根据光谱和化学降解推断.基于分子轨道跟踪法和激发分子基础轨道对间的键序变化讨论.标题化合物最合理的开环模式是同面的1,3氢迁移.     

铱配合物催化下不饱和仲醇的氢转移反应

报导了IrH5(i-Pr3P)2(1)对不饱和仲醇的反应, 发现(1)可以催化分子内氢转移反应, 使不饱和仲醇转变为酮, 讨论了这一反应机理.     

直接由SiO2低温合成含硅环氧化合物及其结构表征

研究了直接由SiO2(沉淀白炭黑)、乙二醇、KOH为原料低温合成高活性的五配位有机硅络合物[KSi-(OCH2CH2O)2OCH2CH2OH]然后与环氧氯丙烷反应,生成含硅环氧化合物,并借助于红外、核磁共振、热分析、能谱元素分析等现代测试手段,对合成的产物进行了结构表征。     

Photoreactions of 16O in self-consistent RPA theory: (III). Polarized (γ, p) and (γ, n) angular distributions and inverse capture reactions below 60 MeV

Polarized ¹⁶O(γ, p₀) and ¹⁶O(γ, n₀) reactions below 60 MeV are analyzed in the framework of a self-consistent RPA theory with the Skyrme force Sk3. The calculations include dipole and quadrupole transitions in LWA. Asymmetries, polarizations and analyzing powers are calculated and compared with the available experimental data. Our aim is to show to what extent polarized results give additional information to that extracted from the unpolarized ones, both on the many-body structure of the nucleus and on the nature of the reaction mechanism at intermediate energies.     

改性Y沸石上的氢转移反应

本文试图用环已烯和邻二甲苯两典型反应考察改性Y沸石的氢转移反应性能。发现在改性Y沸石上环已烯的氢转移, 异构化和聚合反应时发生。在反应开始时SY沸石的氢转移反应和异构化反应活性与铝含量之间的关系与沸石强酸量和铝含量的关系一致, 呈火山形曲线, 极大值在Al/(Al+Si)为0.15左右, 结焦以后反应总转化迅速下降, 且氢转移活性和异构化活性随铝含量减少而单调下降。USY沸石的氢转移活性大幅度降低。在改性Y沸石上邻二甲苯异构化和歧化反应同时进行, SY沸石的歧化反应变化规律与环乙烯氢转移反应相似。当沸石样品中有大量非质子酸位存在时, 两个反应的数据会出现予盾。     

Pulse radiolysis of 3-pyridine methanol and 3-pyridine carboxaldehyde in aqueous solutions

Reactions of e_aq^-, H-atom and OH radicals with 3-pyridine methanol (3-PM) and 3-pyridine carboxaldehyde (3-PCA) have been studied at various pHs using pulse radiolysis technique. e_aq^- was found to be highly reactive with both 3-PM and 3-PCA (k approx. 10¹⁰ dm³ mol¹ s^-1). Semi-reduced species formed in both cases were strongly reducing in nature. In the case of 3-PM, electron addition leads to the formation of pyridinyl radicals whereas in the case of 3-PCA, PyCHOH type radicals are formed. At pH 6.8, H-atom reaction with 3-PCA also gives semi-reduced species (PyCHOH), whereas at pH 1, H-atoms add to the ring. (CH₃)₂˙COH radicals were found to transfer electron to 3-PCA at all the pH values tested and by making use of changes in the absorption spectra, pK_a values of the semi-reduced species were determined to be 4.5 and 10.6. OH radicals were found to undergo addition reaction with 3-PCA, whereas in the case of 3-PM they reacted by H-abstraction as well as addition reaction. By following the yield of methylviologen radical cation formed by electron transfer reaction, it was estimated that approx. 50% of OH radicals react with 3-PM by H-atom abstraction at pH 6.8, giving reducing radicals, whereas at pH 3.2, where 3-PM is in the protonated form, the same is only about 10%. At pH 13, O^-˙ radical anions were found to react exclusively by H-atom abstraction. Reaction of SO₄^-˙ radicals with 3-PCA was found to give a species identical to the one formed by one electron reduction of nicotinic acid at acidic pH values.     

应用分割矩阵全局优化算法设计用于编码孔径成像的二维阵列

二维编码阵列是编码孔径成像的关键部件,它直接决定着再现的层析图像的质量。目前仍没有一种理想的二维阵列既具有较高的量子收集率,又具有良好的层析成像特性。采用一种新的方法———分割矩阵(DIRECT)全局优化算法,设计二维阵列,该算法适用于多变量“黑盒”问题的求解,并且具有比其他优化算法更快的收敛速度。其目的是设计一类自相关函数旁瓣最大值为1,同时具有最大填充率的二维编码阵列。理论分析及实验结果表明:用该算法搜索得到的二维阵列既具有较高的量子收集率,又具有良好的层析成像特性。