机磷农药的 31P NMR 谱的研究

采用600 MHz NMR谱仪较详细地研究了不同类型有机磷农药的NMR谱图, 分析了复杂偶合、直变异构、受阻旋转、手性碳原子等因素对有机磷农药的NMR谱图影响.     

THE 31P NMR INVESTIGATION OF PHOSPHORUS BURNS

为了明确磷烧伤创面及吸收毒性物质的化学形式及分布.作者采用\+\{31\}P NMR波谱,研究皮下注射黄磷、磷酸及磷烧伤后创面残留、肝脏及脑组织吸收的元素磷及其化合物含量.其结果皮下注射非致死与致死剂量的黄磷后,肝脏可测到元素磷的吸收,磷燃烧后创面磷绝大部分转化为磷酸及其结合物,极少部分以元素磷形式存在.致死面积的磷酸烫伤与磷烧伤后肝脏区域磷酸增加4～5倍,未检测到元素磷的波谱,各组脑组织均未检测到元素磷峰,而磷酸峰只有微小的增加.结论为磷烧烧后吸收的主要中毒物质与创面残留的主要化学物质一致,磷烧伤中毒的致死性主要是创面磷酸吸收所致.     

Magnetic field dependence of 11B NMR in CeB6

The ¹¹B nuclear magnetic resonance in a dense Kondo system CeB₆ has been observed by the spin echo technique below 4.2 K at fixed frequencies of 2.5, 6.5, 13.33 and 18.00 MHz, which correspond to magnetic fields of 1.83, 4.76, 9.76 and 13.18 KOe for the free ¹¹B nucleus, respectively. The spectra in the phase II appeared to have two peaks in the magnetic field applied in the [111] direction, the spacing of which was found to be very small in zero external field and increased monotonically (up to 0.11 kOe at 2.6 K) with increasing field. On the other hand, the spectra in the phase III were complex. Especially, the spectra observed for [111] at 6.5 MHz were found to spread over 1.9 KOe and to have several peaks. From comparison between the experiments and the dipolar field calculation based on the recent neutron diffraction measurements, possible magnetic structures were examined for the phases II and III.     

Study of 11B at high excitations with the 9Be(3He,p)11B and 9Be(α, d)11B reactions

The nucleus ¹¹B has been studied over the excitation energy range from 8.5 MeV to 21.5 MeV with the ⁹Be(³He, p)¹¹B / reaction at / E_{³He = 38 MeV}. The analogs of the parent states in ¹¹Be have been located at 12.56, 12.92, 14.40, 16.44, 17.69, 18.0, 19.15 and 21.27 MeV. A complementary measurement with the ⁹Be(α, d)¹¹B reaction at E_α = 48 MeV demonstrates that the 16.44, 17.69, 18.0 and 19.15 MeV resonances have rather pure isospin $\text{T}{}_{\mathrm{f}}\text{=}\text{3}\text{2}$. The 14.40 MeV state is a strongly isospin-mixed analog of the $\text{5}\text{2}{}^{\mathrm{+}}\text{1.78}\text{MeV}$ state in ¹¹Be. It is argued that spin S = 1 transfer is involved in the excitation of the 16.44 MeV state and its 3.887 MeV parent in ¹¹Be in a two-step stripping process. The $\text{T}{}_{\mathrm{f}}\text{=}\text{1}\text{2}$ states and the lowest three $\text{T}{}_{\mathrm{f}}\text{=}\text{3}\text{2}$ states are compared with the predictions of DWBA utilizing shell-model form factors. It is concluded that the $\text{T}{}_{\mathrm{f}}\text{=}\text{1}\text{2}$ strength is more strongly fragmented than is implied by the calculations of Teeters and Kurath.     

Evidence for assignment of 14.0 MeV state in 11B from 10B(n,n)10B

The differential cross section and polarization for neutrons scattered from ¹⁰B have been measured at E_n = 2.63 MeV (E_x = 13.85 MeV). The results of this experiment and other available neutron scattering data in the range 1 < E_n < 4 MeV are interpreted through a single-level R-matrix calculation over the region 12 < E_x < 15 MeV. Based on this analysis the most probable J^π assignment for the 14.0 MeV level in ¹¹B is $\text{11}\text{2}{}^{\mathrm{+}}$. The anomaly near E_x = 13.1 MeV can only be explained in terms of two overlapping levels having assignments of ($\text{5}\text{2}$, $\text{7}\text{2}$)^? and ($\text{3}\text{2}$, $\text{5}\text{2}$, $\text{7}\text{2}$)⁺.     

Structure study of 12B from the elastic scattering of neutrons from 11B

Differential cross sections for neutrons scattered from ¹¹B have been measured for 2.2 MeV < E_n < 4.5 MeV. The differential cross section σ(θ) is fitted reasonably well by R-matrix parameters for broad states in ¹²B with assignments 1 ^? and (1) ⁺ at excitation energies E_x = 5.8 and 6.8 MeV respectively. The broad 1 ^? state has not been previously observed and is believed to be the 1 ^? member of the $\text{1}\text{p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}{}^{\mathrm{?1}}\text{1}\text{d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}$ particle-hole multiplet predicted to exist by earlier shell model calculations. Its existence completes the identification of all of the levels of this multiplet (3 ^?, 2 ^?, 4 ^?, 1 ^?). The broad (1)⁺ level at E_x = 6.8 MeV has not been previously observed. States at excitation energies E_x = 5.61, 5.73 and 6.6 MeV have been assigned spins and parities of 3⁺, 3^? and (1)⁺ respectively. These states had previously been assigned spins of 2, 3 and $\text{≧ 1}$ respectively. Work on T = 1 states in ¹²C¹ has been compared with the present work.     

氧化硼玻璃的11B变温核磁共振研究

本文应用变温核磁共振(NMR)技术研究了氧化硼(B₂O₃)玻璃从玻璃态至融熔态之间的结构变化。实验表明,T>430℃时,以硼氧组环为基本组成单元的玻璃态结构开始解体;600℃2O₃双棱锥体分子相互连接而成的链状结构。链结构在T>930℃时发生断裂,最终成为游离的B₂O₃分子。 关键词：     

Fusion and neutron-transfer cross sections for 13C + 10B and 13C + 11B reactions at subbarrier energies

The cross sections for the ¹⁰B(¹³C, ¹²C)¹¹B neutron-transfer reaction, leading to the ¹¹B 4.45 and 6.74 MeV and ¹²C 4.44 MeV excited states, and for ¹³C + ¹⁰B fusion have been measured by the characteristic and total γ-ray yield methods, respectively, over the energy (c.m.) interval 2.4–5.8 MeV. For ¹³C + ¹¹B, with no transfer reactions present, the fusion cross sections have been measured between E_c.m. = 2.3 and 6.4 MeV. The fusion cross sections for ¹³C + ¹⁰B and ¹³C + ¹¹B are found to be almost equal and slightly enhanced with respect to those for ¹²C + ¹⁰B and ¹²C + ¹¹B.     

Elastic magnetic electron scattering from 29Si and 31P

Elastic magnetic electron-scattering form factors from ²⁹Si and ³¹P have been measured in the range of momentum transfer from 1.0 to 2.8 fm^?1. Analysis of the data using a particle-core-coupling model yields $\text{2}\text{s}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ occupation probabilities for the valence nucleon of 0.46 ± 0.01 for the neutron in ²⁹Si and 0.48 ± 0.01 for the proton in ³¹P. The radius of the $\text{2}\text{s}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ proton orbit in ³¹P has been found to be (5.3^+2.6_?1.5)% larger than the corresponding neutron orbit in ²⁹Si. Recent large-basis shell-model calculations of the form factors do not accurately reproduce the experimental results.     

The 26Mg(14N, 10B)30Si and 26Mg(14N, 11B)29Si reactions

Reactions induced by ¹⁴N on ²⁶Mg at bombarding energies of 60–95 MeV have been studied. Angular distributions for states populated in ²⁹Si by the (¹⁴N, ¹¹B) reaction and in ³⁰Si by the (¹⁴N, ¹⁰B) reaction have been compared with Hauser-Feshbach and DWBA calculations to determine the reaction mechanism and to deduce spectroscopic information. The cross sections for the states populated in ²⁹Si and ³⁰Si are in poor agreement with statistical model calculations, indicating a non-compound nucleus mechanism.     

Proton capture by 11B above the giant resonance

The cross sections for proton capture by ¹¹B to the ground and excited states of ¹²C have been measured in the proton energy interval between 18 and 43 MeV. The ground-state cross section shows good agreement with theoretical calculations including correlations. Capture photons have also been observed to all the residual 1p-1h states of ¹²C having a dominant $\text{1}\text{p}{}^{\mathrm{?1}}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ hole: the corresponding cross sections systematically show a giant resonance whose energy increases with the increasing excitation energy of the “background” level. The resonances at 27.4, 31, 33.2, 37 and 43 MeV, seem to show observable interference effects.     

Nuclear magnetic resonance of 11B in CrB2

From measurements of the ¹¹B NMR in CrB₂ the transferred hyperfine field due to the neighboring magnetic moments of Cr and the temperature dependence of T₁ have been investigated. It is suggested that CrB₂ is not in the weakly itinerant antiferromagnetic regime but is in the stronger or intermediate regime.     

11Li,14Be和17B核的软偶极共振模式

假定¹¹Li,¹⁴Be和¹⁷B核是由核芯和两个外层中子所组成,用Sum Rule探讨这类核的巨偶极共振,给出软偶极共振的能量和强度。结果与其它理论计算进行了比较。 关键词：     

Optical model parameter searches for 16O + 11B elastic scattering

The direct search with pattern search technique of Hooke and Jeeves has been programmed to search for heavy-ion optical model parameters and the results of unconstrained searches using this method for ¹⁶O + ¹¹B elastic scattering are presented.     

xNa2O·yB2O3玻璃的融熔态结构

本文应用变温核磁共振技术研究了xNa₂O·yB₂O₃二元玻璃体系的融熔态结构。结果表明,R≤0.5的熔体中存在两种较为稳定的结构:在730—780℃温度区域形成了B原子间以双桥氧连接的网状结构;在880—920℃温度区域形成了B原子间含三桥氧的链状结构。当R>0.5时熔体中只存在第一种结构。 关键词：     

The α-transfer reactions 27Al(6Li,d)31P, 29Si(6Li,d)33S and 31P(6Li,d)35Cl at 36 MeV

The α-transfer reactions ²⁷Al(⁶Li, d)³¹P, ²⁹Si(⁶Li, d)³³S and ³¹P(⁶Li, d)³⁵Cl have been studied at a ⁶Li energy of 36 MeV. Absolute cross sections and angular distributions have been measured and an exact finite-range distorted-wave Born approximation analysis assuming a direct cluster transfer has been used to extract from the data α-particle spectroscopic strengths for levels populated in ³¹P, ³³S and ³⁵Cl in the three reactions respectively. The results show that in the case of most of the low-lying excited states of ³¹P, a single value of L of the transferred α-particle contributes, though a multiplicity of L-values are allowed by angular momentum selection rules. It is also found that the α-particle spectroscopic strength of the ground state of ³¹P is a factor of 2 more than the strengths of the ground states of ³³S and ³⁵Cl. The α-spectroscopic strengths of ground states of these, as well as other odd-A s-d shell nuclei, are compared with the presently available shell model calculations.     

Polarization of 12B in deep-inelastic heavy-ion reaction 100Mo(14N, 12B)

Spin polarization of ¹²B was measured for ¹⁰⁰Mo(¹⁴N, ¹²B) at $\text{E}{}_{\mathrm{<mtext>i</mtext>}}\text{(}{}^{14}\text{N}\text{) ? 200}\text{MeV}$ as a function of $\text{Q}$ value down to $\text{Q ? ?150}\text{MeV}$, and was found anti-parallel to $\text{k}{}_{\mathrm{f}}\text{×}\text{k}{}_{\mathrm{i}}$ in the deep-inelastic region. The data together with those at lower incident energies show a systematic trend in $\text{Q}$-value dependence of the polarization.     

The compound nucleus reaction 12C(11B, 2α) 15N

Energy spectra and differential cross sections of nitrogen products formed in the reaction 28 MeV ¹¹B + ¹²C have been measured using a ΔE?E counter telescope. The energy spectra are smooth and therefore indicate that the nitrogen products were formed by a compound nucleus mechanism, via the formation and decay of the compound nucleus ²³Na. The experimental results are compared with statistical model calculations and good agreement is obtained. This result provides further evidence for the importance of the compound nucleus mechanism in heavy ion reactions with light nuclei and also gives added validity to the statistical model for light compound systems.