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P. Brix A. Körding K. H. Lindenberger 《Zeitschrift für Physik A Hadrons and Nuclei》1959,154(5):569-573
Argon gas has been irradiated with 34 MeV bremsstrahlung. The yields of the reactions A40(γ, p) Cl39 and A40 (γ, np) Cl33 were determined relative to C12(γ, n) by β-counting. The resulting upper limits for the cross sections integrated to 28 MeV are 160 MeVmbarns for (γ, p), and 35 MeV mbarns for (γ, np). This does not confirm the anomalously high A40 (γ, p)-cross section reported in the literature. 相似文献
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《中国物理C(英文版)》2019,(10)
Motivated by the rapid development of heavy flavor physics experiments, we study the tree-dominated nonleptonic ■_(u,d,s)~*→ D_(u,d,s)~*V(V = D_(d,s)~(*-), K~(*-), ρ~-) decays within the factorization approach. The relevant transition form factors are calculated by employing the covariant light-front quark model. Helicity amplitudes are calculated and analyzed in detail, and a very clear hierarchical structure |H-0| ≈ 2|H00| |H0-| ≈ |H| |H0+| ≈ |H++| is presented.The branching fractions are computed and discussed. Numerically, the CKM-favored ■*q→ D_q~*ρ~-and D_q~*D_s~(*-) decays have relatively large branching fractions, ■O(10~(-8)), and could be observed by LHC and Belle-II experiments in the future. 相似文献
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Rudolf Rodenberg 《Zeitschrift für Physik A Hadrons and Nuclei》1961,162(4):347-357
The ratio of the differential cross section for the (e, N)-process to the total (γ,N) -cross section is derived with the use of the relativistic Coulomb Eigenfunctions for the continuous spectrum. For electric and magnetic dipole transitions the Born approximation, the Coulomb correction, the effect of screening and that of finite nuclear size are calculated. In this angular distribution there should be no interference of electron waves scattered by different multipoles, where the inelastically scattered electrons are detected. Numerical calculations have been done for nuclei withZ=6, 29, and 82 and scattering anglesθ=1Ω, 132Ω, 160Ω and 180Ω of the electron. The result of this theory is compared with the experiments of W.C.Barber et al. 相似文献
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A series of organotin(IV) complexes of composition R3Sn[O2CC6H4{N= C(H)C6H3-2-OH(N=NC6H4R)}-p] (R = Ph or Bz; R = H, 2-CH3, 3-CH3, 4-CH3) have been investigated by 119Sn Mössbauer, 1H, 13C, 119Sn NMR and IR spectroscopic techniques. 119Sn Mössbauer data indicated a distorted tetrahedral geometry for the triphenyltin(IV) complexes while the tribenzyltin complexes exhibit a distorted trigonal bipyramidal coordination geometry with equatorial benzyl groups and the axial positions occupied by an O atom from the carboxylate ligand and the O atom from the water ligand. The 119Sn-NMR chemical shifts confirm that the Sn atom in triorganotin complexes is four-coordinate in CDCl3 solution. 相似文献
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《光谱学与光谱分析》2006,(7)
OFFICIAL SPONSORSNational Natural Science Foundation of ChinaChina Association for Science and TechnologyXiamen Municipal GovernmentORGANIZERSChinese Chemical SocietyChinese Physical SocietyChinese Spectroscopy SocietyXiamen UniversityInternational Scientific Advisory BoardBarnes RM(USA)Bolshov MA(Russia)Brenner IB(Israel)Broekaert J(Germany)de Loos-Vollebregt MTC(Netherlands)Ebdon L(UK)Haraguchi H(Japan)Jiang GB(China)Kawai J(Japan)Kiefer W(Germany)Lee YI(… 相似文献
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(6aR,11aR)-3-羟基-4,9-二甲氧基紫檀烷分子的晶体结构 总被引:1,自引:0,他引:1
从多刺锦鸡儿 (豆科 )中分离得到一个紫檀烷型化合物— (6aR ,11aR) 3 羟基 4,9 二甲氧基紫檀烷 ,通过红外光谱、质谱、核磁共振氢谱、核磁共振碳谱、氢核 氢核相关谱、异核多量子相干谱和异核多键相干谱进行结构鉴定 .其单晶经X射线衍射测试表明 ,该化合物晶体属单斜晶系 ,空间群为P2 1 ,化学式为C1 7H1 6 O5,Mr =3 0 0 .3 0 .晶胞参数为 :a =6.4778(13 ) ,b =12 .63 1(3 ) ,c=8.83 68(18) ,β =95 .80 (3 ) o,V =719.3 (3 ) 3,Z =2 ,Dc=1.3 86Mg/m3,F(0 0 0 ) =3 16,μ =0 .10 2mm- 1 .结构由直接法解出 ,用全矩阵最小二乘法修正 ,最终偏离因子R =0 .0 3 3 2 ,wR =0 .0 862 .该分子由一个苯并吡喃环和苯并呋喃环组成 ,X射线衍射测试表明其绝对构型为顺式紫檀烷型 相似文献
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Total cross sections and excitation functions up to 11·8 MeV have been measured for the Ce142(d,p), -(d,n) and -(d, 2n) reactions by the activation method. The cross sections found forE d=11·8 MeV are 187mb, 54 mb and 535 mb, respectively. By comparing these results with cross sections calculated from the statistical theory of nuclear reactions it can be shown that the (d,p)-reaction and nearly the whole (d,n) -reaction proceed by stripping mechanism. 相似文献
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采用量子化学计算方法研究了2-(N,N-二乙基苯胺-4-基)-4,6-双(3,5-二甲基吡唑-1-基)-1,3,5三嗪(dpbt)聚合物的电子结构和光物理性质,并且用二维实空间和三维实空间分析方法进行理论研究.结果表明, dpbt聚合物的第一激发态为分子内电荷转移激发态,存在较大的电偶极距变化和极化率,其中电偶极距变化与实验数值符合较好,理论计算所得到极化率数值与实验结果一致.S1激发态存在较大的电偶极距变化和极化率会导致非线性光学效应,促使高效的双光子吸收截面的形成.同时对外电场变化时dpbt的激发态性质进行理论研究. 相似文献
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为研究聚乙炔(PA)的分子结构及振动光谱,对反,反-2,4-己二烯(TTHF)和顺,反-2,4-己二烯(CTHE)进行了红外(IR)和拉曼(Raman)光谱的检测和简正振动分析。主要结果如下: (1) TTHE的C_2h分子对称性,导致真观测谱带严格遵守IR-Raman相互排斥规则。而CTHE的分子不对称性,使其并无此现象发生。(2) TTHE和CTHE的简正振动分析都得到了42个非零的计算频率,这是符合3N-6规则的。(3) 计算所得TTHE和CTHE的位能分布值,与我们听做的经验指认吻合得较好。伹TTHE和CTHE的大部分骨架的简正振动模式都是由多个经验模式的贡献,这表明了平面和共轭结构所造成的骨架振动的复杂性。(4) 对TTHE和CTHE进行力场精化,所得计算频率与观测值的平均绝对偏差为14cm~(-1),平均相对偏差为1.8%。 相似文献
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合成了一种新型的蓝光发射材料2,6-双(2-苯并咪唑)吡啶-乙酸锌,并利用元素分析、红外光谱、UV-Vis吸收谱、荧光激发光谱和荧光发射光谱研究了其结构、光学特性、能级结构和发光机理。结果表明,2,6-双(2-苯并咪唑)吡啶-乙酸锌是一种三齿配体的发光材料。在N,N-二甲基甲酰胺(DMF)溶液体系中测定了材料的紫外吸收光谱,2,6-双(2-苯并咪唑)吡啶的吸收峰波长主要为330,344nm;2,6-双(2-苯并咪唑)吡啶-乙酸锌的吸收峰波长主要为346,366nm。禁带宽度为3.01eV,在紫外光激发下,在DMF溶液体系中的荧光发射峰在458nm处,固态荧光发射峰在475nm,均为蓝色荧光,色纯度高,荧光量子效率高,其荧光发射主要来源于长波吸收带,最大波长吸收带对荧光发射贡献最大。有望通过合理的设计运用到有机电致发光器件中去。 相似文献
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使用先进的量子化学ab initio程序MONSTERGAUSS和各种基函数组,在较大的核间距内计算了锂-锂,氟-氟原子间的位能曲线。并采用组态相互作用(CI)方法计算了基态锂分子(Li2 1∑g+)和基态氟分子(F2 1∑g+)的平衡核间距及总能量。计算结果与其它理论和实验结果进行了比较。 相似文献
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运用分子轨道理论中的半经验AM1、PM 3方法和Hartree Fock从头算方法 ,通过能量梯度全优化率先计算了新近合成的化合物N ,N 二 (8 羟基 5 喹啉甲基 )甘氨酸乙酯的平衡几何构型、电子结构以及生成热、偶极矩等分子基本性质 ,并联系经典有机电子结构理论进行讨论。三种方法得到的结构参数基本一致 ,和实验测量的晶体结构符合较好。在稳定构型基础上 ,用AM1方法进行正则振动频率分析 ,得到C—C双键、C—N单双键、C—O单双键和羟基OH的振动基频 ,和实验测得的红外光谱特征峰吻合较好 相似文献
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G. Breuer 《Zeitschrift für Physik A Hadrons and Nuclei》1964,178(3):268-286
Investigating reaction mechanisms, angular distributions and cross sections of the reaction B10(d, p) B11 have been measured in the energy interval from 1,4 to 3,3 MeV of deuteron energy. More detailed measurements than until known have shown, that besides the well known stripping mechanism withl n =1 contributions of compound nucleus formation are not neglectable. Especially atE d =2,3 MeV,E X (C12)=27,1 MeV, the effect of a single resonance contributes a great deal to the cross section of the groupsp 1 andp 3 . Further angular distributions and yield curves between 1,4 and 3,3 MeV have been measured in the (d, α)-reactions on B10 and B11, showing quite different behaviour for both target nuclei. 相似文献
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运用分子轨道理论中的半经验AM1、PM3方法和Hartree-Fock从头算方法,通过能量梯度全优化率先计算了新近合成的化合物N,N-二(8-羟基-5-喹啉甲基)甘氨酸乙酯的平衡几何构型、电子结构以及生成热、偶极矩等分子基本性质,并联系经典有机电子结构理论进行讨论.三种方法得到的结构参数基本一致,和实验测量的晶体结构符合较好.在稳定构型基础上,用AM1方法进行正则振动频率分析,得到C-C双键、C-N单双键、C-O单双键和羟基OH的振动基频,和实验测得的红外光谱特征峰吻合较好. 相似文献