BaMgAl_(10)O_(17)∶Eu~(2 )的MgF_2表面包覆(英文)

采用溶胶-凝胶法对蓝色荧光粉BaMgAl10O17∶Eu2 (BAM)进行表面包膜处理,获得了表面均匀包覆MgF2膜层的BAM荧光粉。并用SEM、XRD和IR手段对其表面形貌、晶格结构性能进行了表征;用EDS对BAM粉体的表面元素进行了定性分析;用荧光光谱测试对荧光粉的发光性能进行了研究。结果表明,在BAM粉体表面均匀包覆MgF2层后,BAM的晶格结构,发光性能没有改变,初始亮度较未包覆的荧光粉有所降低,经过相同条件的热处理后,包覆MgF2荧光粉的亮度热衰减程度明显低于未包覆的荧光粉,且色坐标偏移现象不明显。     

化合物(Et4N)2[Pd2(mp)2(μ-mpH)2]的NMR研究

采用¹H-¹H COSY,HMQC、HMBC等2D NMR技术对化合物(Et₄N)₂[Pd₂(mp)₂(μ-mpH)₂]进行¹H、¹³C NMR谱数据分析与归属,表明它在DMSO溶液中仍保持原有固体状态的分子结构.     

广义相对论浅释(2)

2广义相对论时空前面谈到：让两根放在一起时完全相同的标尺,一根静止在引力场中,一根静止在引力场外,二者还相同吗？让两组放在一起时完全相同的钟,一组静止在引力场中,一组静止在引力场外,二者还相同吗？本节将要回答这两个问题了．首先谈一下物理实验中如何测量时间和空间‘要测量时间,就要先选择某一周期性的自然过程作为时间的标准,这样就可用它来测量任意过程的时间了．例如可选择某种单色光的振动周期作为时间标准,铭原子钟即此道理．选作时间标准的周期性的自然过程称作时钟．物理实验中测量时间所用的就是这种真实的时钟…     

Spontaneous SU(2) symmetry violation in the SU(2) L × SU(2) R × SU(4) electroweak model

A new approach to electroweak (EW) composite scalars is developed starting from the fundamental gauge interaction on high scale. The latter is assumed to have the group structure SU(2) _L × SU(2) _R × SU(4), where SU(4) is the Pati-Salam color-lepton group. The topological EW vacuum filled by instantons is explicitly constructed and the resulting equations for fermion masses exhibit spontaneous SU(2) flavor symmetry violation with possibility of very large mass ratios.     

二茂铁双核铜配合物Cu2(dmaf)2(CH3COO)4(Ⅰ)和Cu2(dmaf)2(C6H5COO)4(Ⅱ)的光谱研究

室温下合成了含有二茂铁基的双核铜配合物Cu2 (dmaf) 2 (CH3 COO) 4 (Ⅰ )和Cu2 (dmaf) 2 (C6H5COO) 4(Ⅱ ) [dmaf=(dimethylaminomethyl)ferrocene]。采用扫描电镜半定量测定标题化合物成分 ,用X射线衍射法测试 ,并确定两者的晶胞参数 ,发现两者有相似的晶体结构。最后对标题物的红外、远红外、固体漫反射电子光谱、循环伏安法 (CV)等谱学性质进行深入研究。结果表明 ,两个配合物紫外吸收波段分别为 2 34～2 6 9nm和 2 4 5～ 2 80nm ,在可见光区出现了一个d d跃迁宽域带 ,其循环伏安曲线表明 ,两个化合物的氧化还原电位分别为 0 5 3,0 37和 0 6 2 ,0 36V。     

Bi_(1.9)Sb_(0.1)Sr_2Ca_2Cu_(2+x)O_y 的超导特性(x=0,0.4,0.8,1.0,1.2,1.6)

文中报道了 Bi_(1.9)Sb_(0.1)Sr_2Ca_2Cu_(2+x)O_y,系列的交流磁化率测量及 X 射线衍射结果,发现超导转变温度对于 Cu 的组份非常敏感,当 x=0.4时,样品在136.5K 出现抗磁性,其 X 射线衍射图中新相衍射峰较85K 超导相的峰更强,因此 Cu 的价态和配位数在形成高和 T_c 超导相中起着至关重要的作用.     

(C_5H_(11)N_2)~+和(C_7H_(12)N_2)~(2+)的NMR研究

结合1H NMR,13C NMR谱,分别对钨、钼配合物{WO2(C10H6O2)2(C5H11N2)2[H2N(CH2)3NH2]}3(1),{(C5H11N2)2[H2N(CH2)3NH2][MoO2(C10H6O2)2]}(2),{(C7H12N2)2[MoO2(C10H8O2)2]}(3)晶体结构中小分子环进行了归属.其中,配合物1和2中(C5H11N2)+的NMR研究证实了六元环由1,3-丙二胺和乙腈化合而成,配合物3中(C7H12N2)2+的NMR谱图证实了七元环由乙二胺和乙酰丙酮化合而成,并且推导出这些亲核加成-消除反应的反应机理.配合物1~3中的小分子环的合成在其它体系中尚未见报导,而在合成它们的反应中作为新产物随主体晶体析出,并由晶体结构解析和NMR得到了证实.     

Co~(2 )-Ti~(4 )和Cu~(2 )-Nb~(5 )离子取代BaFe_(12)O_(19)单晶体中Fe~(3 )离子的研究

本文对用Co~(2 )-Ti~(4 )和Cu~(2 )-Nb~(5 )离子取代BaFe_(12)O_(19)单晶体中Fe~(3 )离子进行了研究,以Bi_2O_3作为助熔剂生长出了BaFe_(12-2x)Co_x~(2 )Ti_x~(4 )O_(19)(x=0;0.04;0.09;0.13;0.27和0.68)以及BaFe_(12-x)[Nb_(1/3)~(5 )Cu_(2/3)~(2 )]_xO_(19)(x=0;0.28;0.44和0.60)这两系列的单晶体,测定了100—300K温度范围内样品的磁化强度σ与单轴各向异性常数K_1,我们发现,对CO~(2 )-Ti~(4 )取代的样品,当x≤0.09时,其σ与K_1随x的增加而缓慢增加;当x>0.09时,其σ与K_1随x的增加而迅速降低,至x=1.1时,K_1变为零,对Nb~(5 )-Cu~(2 )取代的样品,其σ值在整个成份范围内基本保持不变,且有缓慢增加趋势;而K_1值则随x增加而单调下降,提出了取代离子在M型六角铁氧体中可能的分布模型来解释我们的结果。     

Order-disorder transition on Si(001): c(4 × 2) to (2 × 1)

A phase transition between c(4 × 2) and (2 × 1) structures on the clean Si(001) surface has been observed at about 200 K by low energy electron diffraction. From the temperature dependence of the width and intensity of the diffraction spots this transition is concluded to be a second order order-disorder transition. The transition proceeds by a single stage, which is in strong contrast with the case of Ge(001) for which a two-stage transition has been reported.     

Analytical Potential Energy Function for Doubly Charged Ions O_2~(2 ), Be_2~(2 ) and He_2~(2 )

1　ＩＮＴＲＯＤＵＣＴＩＯＮＩｎ1933,ＰａｕｌｉｎｇｅｘｐｌａｉｎｅｄｔｈｅｅｘｉｓｔｅｎｃｅｏｆｍｅｔａｓｔａｂｌｅＨｅ2 2ｉｎｔｅｒｍｓｏｆｃｏｖａｌｅｎｔｉｏｎｉｃｍｉｘｉｎｇｏｆｔｈｅｓｔｒｕｃｔｕｒｅｓＨｅ Ｈｅ (ｒｅｐｕｌｓｉｖｅ)ａｎｄＨｅ2 Ｈｅ(ａｔｔｒａｃｔｉｖｅ).Ｔｈｉｓｐａｐｅｒｓｉｇｎａｌｓｔｈｅｂｅｇｉｎｎｉｎｇｏｆａｓｅｒｉｅｓｏｆｐｕｂｌｉｃａｔｉｏｎｓｏｎｄｏｕｂｌｙｃｈａｒｇｅｄｄｉａｔｏｍｉｃｍｏｌｅｃｕｌｅｓ.Ｄｏｕｂｌｙｃｈａｒｇｅｄｍｏｌｅｃｕｌａｒｃａｔｉ…     

High-Resolution Spectroscopy of Jet-Cooled (32)SO(2) and (34)SO(2): The ã(3)B(1)-;X(1)A(1), 2(1)(0) and 1(1)(0) Bands

Laser-induced excitation spectra of the two bands ?(3)B(1)-;X(1)A(1), 2(1)(0) and 1(1)(0) of (32)SO(2) and (34)SO(2) have been recorded in a supersonic jet at a resolution of 0.015 cm(-1). The rotational and electron-spin fine structure has been analyzed for both isotopic species. Analysis of the rotational and electron-spin fine structure yields precise values of the rotational constants A, B, and C and the spin constants alpha and beta for both (32)SO(2) and (34)SO(2) in the states ?(3)B(1) (010) and (100). No interaction between these two vibrational states with any nearby triplet state is observed for rotational levels with J 相似文献   

量纲分析简介(续2)

正6威力巨大的Π定理6.1Π定理及其证明量纲分析有一个威力巨大的定理,叫做Π定理[Π是希腊字母,读作pai(汉语拼音)],是E.Buckingham于1914年发表的.该定理的粗略内容是:任何一个涉及n个物理量(指它们的数)的方程都等价于一个只涉及较少个无量纲量的方程.这一等价性使物理问题得以简化,在不少情况下甚至可以利用这一定理(配以适当的物理思辨)直接解决     

Chiral SU(2)×SU(2) model with infrared quark confinement

An SU(2)×SU(2) chiral quark model describing the properties and interaction of pions and scalar and vector mesons is considered. The confinement of quarks is introduced in the model by means of an infrared cut-off in the one-loop quark diagrams. This cutoff gives rise to the elimination of the unphysical thresholds of the quark-antiquark pair production. The π-a ₁ transitions are taken into account. The model conserves all low-energy theorems. The masses of mesons and the widths of the decays ρ → 2π and σ → 2π are calculated.     

Carbon monoxide chemisorption on Cu(100)-c(2 × 2)Pd

Chemisorption of carbon monoxide on Cu(100)-c(2 × 2)Pd was investigated using ultraviolet photoelectron spectroscopy. Adsorption was found to occur molecularly with a saturation coverage at 100 K which is approximately the same as that on Cu(100). Desorption spectra indicate that the CO-surface bond strength for the majority of the molecules is intermediate to that for the pure metals. The 4σ satellite, characteristic of photoemission from CO on Cu, was not observed.     

NO分子(5σ)~2(1π)~43p-(5σ)~2(1π)~3(2π)~2构形相互作用与转动能级结构

在考虑ＮＯ分子的（５σ）２（１π）４３ｐ－（５σ）２（１π）３（２π）２构形相互作用的情况下，对Ｄ２Σ＋（ｖ＝６），Ｃ２Π（ｖ＝６），Ｂ２Π（ｖ＝２４）和Ｌ２Π（ｖ＝４）电子态的转动能级结构以及态函数进行了计算，计算结果与实验结果很相符。     

Surface phonon dispersion of Cu(100)c(2×2)N

The Cu(100) surface covered with atomic nitrogen has been studied with low energy electron diffraction (LEED), Auger electron spectroscopy (AES) and inelastic electron scattering (EELS). Atomic nitrogen, formed by thermal dissociation of NH₃ adsorbed at 100 K, forms a c(2×2) overlayer on the Cu(100) surface. The dispersion of adsorbate and substrate associated modes of the Cu(100) surface covered with a c(2×2) nitrogen overlayer has been measured along the two dimensional Brillouin zone in the - by inelastic electron scattering. The experimental data are compared to a lattice dynamical slab calculation. The Rayleigh-mode (S₄-phonon) is only slightly changed by the N-overlayer. An optimum fit for the perpendicular and parallel nitrogen modes (=320 cm^–1 and =740 cm^–1 at =0.1) is obtained when the nitrogen atom is placed 0.6 Å above the first copper layer.     

量子材料大观园(2)

渔家傲·风月文章焉入十年风月里,低吟秋水万千思。秀色文章难数已,重拾起,铅华不过平常记。尚忆当时青涩事,一横一竖与君寄。麾汗换来凌雪意,如今是,梅枝一夜红黄系。Ⅵ.钛酸锶是个神奇的世界SrTiO3(STO)是一种神奇的材料,她是绝佳的绝缘体、氧化物单晶衬底、漂亮的装饰物。不过,她神奇之处在于她的泰国人妖之面貌,经过简单化妆,她可以是金属、超导体、量子顺电体、铁电体、热电材料、光催化材料…天知道还会有什么人能够再捣鼓出来什么,比如说拓扑导电绝缘体!     

On superstring-inspired SU(3) × SU(2) × (U(1))2 models with SO(10) unification

Alternative compactification of the heterotic superstring can give rise to a residual four-dimensional SO(10) gauge symmetry for the observable sector. We consider a model with gauge group SU(3) × SU(2) × (U(1))², resulting from the Hosotani breaking of SO(10), study its further gauge symmetry breaking and calculate the particle spectrum. We find that all breakings can occur close to the weak scale; the top mass lies preferentially between 40 and 60 GeV, the second Z boson mass is O(200–400) GeV. The sparticle spectrum is quite heavy, apart possibly from a light chargino, whose mass can be as light as O(30) GeV.