Spectres de vibration du Cristal de Biphényle à Basse Température

Abstract

Low-temperature infrared and Raman spectra of Crystalline biphenyl have been investigated in the 3100–25 cm^?1 range, and those of biphenyl-D₁₀ between 200 and 25 cm^?1. The infrared dichroism of an Oriented crystal at 77°K has been measured in the 3100–400 cm^?1 region. The assignment for the internal modes V ₅(B_2u), v ₆ (B_2u), v ₁(B_1u), v ₁₀(B_1g), v ₂(B_2g) et v ₃ (B_3g) is given.

The band splitting is analized and hte components due ot the correlation effect in the fundamentals are separated from the components due to combinations. Isotopic shifts are used to assign the nine external vibrations as well as the torsional mode. The temperature effect on the frequencies occuring below 500 cm^?1 is discussed.     

Czochralski法生长Lu2SiO5:e晶体的发光特性

本文使用铱坩埚感应加热Czochralski法成功地生长出了无色透明且尺寸达φ50mm×60mm 的Lu2SiO5:e晶体.XRD结构分析表明, 该晶体为单斜结构.在室温下分别以X射线和紫外光为激发源测量了该晶体的发射光谱,获得的发射波长分别为403nm和420nm,光衰减时间为41ns,光产额达32000p/MeV.发射光谱的双峰结构以及晶体的发光特性证明其发光源于Ce3+离子的5d1→5F5/2 和 5d1→5F7/2跃迁.     

Analyse de la Raie Zéro-Phonon et des Processus de Relaxation Excitoniques dans le Spectre d'Absorption Singulet-Triplet du Cristal de 4-4′-Dichlorobenzophenone

Abstract

In this paper we discuss the dynamic scattering information which can be obtained from an analysis, at high resolution, of the triplet exciton absorption band in the molecular crystal 4-4′-dichlorobenzophenone. The zero phonon lineshapes, widths and positions are investigated as a function of temperature. At temperatures below 30 K the broadening and the shift are analyzed in terms of exchange theory involving a torsional mode of the molecule. The lifetime in the phonon promoted state is 0.75 ps over the range 5 K-30 K. The difference between the excited and ground state energies of the torsional mode is δω = -8.45 cm^?1. Above 30 K the change on linewidth is discussed in a model which implies a momentarily localization of the exciton by lattice phonons. During the localization time a weak coupling between the trapped excitation and phonons is assumed. At very low temperatures the lineshape is asymmetric, gaussian on the high energy side, lorentzian on the low energy side. This experimental result may be due to the fact that the k = 0 level is at the bottom of the exciton band.     

Crystal structure of 2-pyridiniumferrocene tetrafluoroborate Fe(η5-C5H5)[(η5-C5H4)(2-C5H4NH+)](BF 4 − )

Protonation of Fe( ⁵-C₅H₅)[( ⁵-C₅H₄)(2-C₅H₄N)]1 in 98% H₂SO₄ followed by dilution with water and addition of NaBF₄ yields Fe( ⁵-C₅H₅)[( ⁵-C₅H₄)(2-C₅H₄NH⁺)](BF ₄ ^– )2 instead of a ferrocinium derivative. Complex2 crystallizes in the monoclinic system, P2₁ /a:a=7.984(1),b=9.981(2),c=18.220(4) Å,=102.31 (1)°,V=1418.5 ų,Z=4. The pyridinium ring makes a dihedral angle of 21.0(2)° with the cyclopentadienyl ring to which it is bound. One F atom of BF ₄ ^– is involved in short van der Walls contacts with the N (2.764(5) Å) and the H (2.08(6) Å) atoms of the NH⁺ moiety.     

5-(thien-2-yl) uracil analogs: 5-(5-methylthien-2-yl)-2′-deoxyuridine, 5-(5-thien-2-yl)-2′-deoxyuridine,and 5-(5-bromothien-2-yl)-2′-deoxyuridine

Crystal structures of 5-(5-methylthien-2-yl)-2-deoxyuridine (I), 5-(5-thien-2-yl)-2-deoxyuridine (II) and 5-(5-bromothien-2-yl)-2-deoxyuridine (III) have been obtained from data collected on a four-circle Enraf-Nonius diffractometer (CAD-4 system). Space group, unit/cell parameters and finalR indices are:I, monoclinic,P2₁,a=9.105(2),b=20.819(2),c=7.932(2) Å, =98.79(2)°,R=5.7%;II, monoclinic,P2₁,a=8.720(4),b=20.793(4),c=7.884(4) Å, =95.06(2)°,R=5.8%;III, monoclinic,P2₁,a=9.260(2),b=41.655(7),c=7.926(2) Å, =97.996(13)°,R=9.4%. Structural properties of the title compounds are compared with those of 5-(5-chlorothien-2-yl)-2-deoxyuridine (IV) previously reported in order to explain their affinity for HSV-1 thymidine kinase and their eventual interaction with viral DNA polymerase. The main structural features observed are the coplanarity of the uracil and thienyl cycles stabilized by a S–O intramolecular interaction and the formation of dimeric intermolecular H bonds between two uracil moieties.     

Magnéli phases in Ti-containing oxides and their solid solutions

The ordered planes of crystallographic shear inherited from titanium dioxide TiO₂ were revealed in complex Ti-containing oxides (Magnéli phases) by powder X-ray diffraction. It is assumed that periodic shear in the structure results in the modulation of titanium and oxygen displacements along the direction normal to the shear planes. A method of calculating the amplitude of the displacements of titanium atoms from the centers of oxygen octahedra is suggested. The method provides good agreement of the calculated and experimental data for single crystals. The degree of A-nonstoichiometry in alkaline earth, cadmium, and lead titanates is evaluated as 2–3%.     

Syncristallisation Organique avec Peritexie. Cas du Système Binaire Fluoro-2 Naphtalene - Naphtol-2

The phase relations in the x 2-fluoronaphthalene-(1 - x) 2-naphthol system have been determined by X-ray diffraction, DTA and heating optical microscopy. Three stable solid phases occur: β which is a solid solution of 2-fluoronaphthalene in the low temperature form of 2-naphthol (OH_II), α which is a solid solution of 2-fluoronaphthalene in the high temperature form of 2-naphthol (OH_II) and α’ which is a solid solution of 2-naphthol in 2-fluoronaphthalene (F_I). The structure of the β phase is derived from the ordered structure OH_II (monoclinic, Ia, Z = 8) whereas the structure of the α and α’ phases are respectively derived from the disordered structures OH_I and F_I (monoclinic, P2₁/a, Z = 2).

The main features of the phase diagram are a transition zone (II-I) for solid solutions rich in 2-naphthol, the limits of which at 293 K are x = 0.20 and x = 0.45 and a peritectic at T _p = 338 K with a miscibility gap from x = 0.60 to x = 0.87; the limits of demixion at 293 K are x = 0.53 and x = 0.95.

This example points out that volume relationships are not decisive in organic solid-state solubilities.

Le diagramme de phases du systeme x fluoro-2 naphthalene-(I - x) naphtol-2 a été déterminé par méthodes radiocristallographique, thermique et optique. Il est de type Roozeboom IV avec un péritectique situé à x = 0.87 et à T _p = 338 K. Il est caractérisé également par un phénomene de polymorphisme Il-I affectant des solutions solides riches en naphtol-2 (forme II: monoclinique, Ia, Z = 8 - forme I: monoclinique, P2₁/a, Z = 2, structure désordonnée).

Cet exemple met en lumière l'insuffisance des seules considerations d'homéomorphisme moléculaire pour décrire les conditions de formation d'un cristal mixte organique.     

X-ray structural and molecular mechanics investigation of cyclopentadienyl-carbonyl-triphenylophosphine-phenylacetyliron, (η5-C5H5)Fe(CO)(PPh3)(COCH2C6H5)

The crystal and molecular structure of cyclopentadienyl-carbonyl-triphenylphosphine-phenylacetyl-iron (1) has been determined on the basis of X-ray data. The crystals are triclinic, space groupP¯1 (Z=2) with cell dimensions:a=9.546(1),b=10.233(1),c=5.012(2) Å,=93.70(1),=101.12(1), =112.58(1)°. The structure was solved by direct methods and refined anisotropically by a full-matrix, least-squares procedure against 4964 independent reflections, givingR=0.0416. The MM calculations done for a model of1 reproduced satisfactorily the X-ray structure.On leave from the Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China.     

BaBPO5晶体的生长研究

本文采用顶部籽晶高温溶液法,以BPO4-NaF为助熔剂,生长了BaBPO5单晶.生长参数:液面以下温度梯度为1.5℃/cm,液面上温度梯度为10℃/cm,晶体旋转速度30r/min,降温速率0.5-1℃/d,可获得尺寸为30mm×20mm×15mm的BaBPO5单晶.测定了所获单晶及其挥发物的X射线粉末衍射图谱,讨论了助熔剂对BaBPO5晶体生长的影响和该晶体的物化性能.     

赝二元系LiF-SrAlF5相图

本文通过差热分析(DTA)和X射线粉末衍射(XRD)方法研究了赝二元系LiF-SrAlF5的相平衡关系.该赝二元系在LiF:SrAlF5=1:1处形成一致融熔化合物LiSrAlF6,其熔点为765℃,并分别在LiF-LiFSrAlF6和LiSrAlF6-SrAlF5区域出现两个低共熔点,其共晶温度分别为673℃和705℃,根据体系的相图,采用坩埚下降法生长出氟化物激光晶体Cr3+:LiSrAlF6.     

Crystal and molecular structure of [Pd(η5-C5H5) (bis-1,2-diphenylphosphinoethane)] [CF3SO3]

The crystal structure of the complex [Pd( ⁵-C₅ H₅) (PPh₂) CH₂CH₂PPh₂]⁺ [CF₃SO₃]^– has been determined from single crystal X-ray data and refined by least-squares methods toR=0.046. The monoclinic crystals have unit cell dimensionsa=9.832(3),b=12.104(4),c=13.765(4)Å,=111.22(3)°, space group P2₁, andz=2. In the cationic complex the palladium atom is coordinated to the ⁵-cyclopentadienyl moiety and to the phoshorus atoms of the chelating diphosphine. The arrangement of the two phosphorus atoms and the centroid of the cyclopentadienyl ring is approximately trigonal.     

Synthesis and molecular structure of the organometallic zwitterion (η5-C5H3MeBCl3)Fe(CO)3: evidence for alternative sites of nucleophilicity within the [(η5-C5R5)Fe(CO)2 − anion

The organometallic zwitterion (⁵-C₅H₃MeBCl₃)Fe(CO)₃ (2) is isolated as a minor product from the reaction between the sodium salt of the anion [(⁵-C₅H₄Me)Fe(CO)₂]^– and boron trichloride. The crystal structure of 2 [P2₁/n, a = 7.3927(5) Å, b = 13.8027(9) Å, c = 12.2759(9) Å, = = 90°, = 92.517(3)°] features discrete molecules in which the coordination sphere of the iron center comprises three carbonyls and a novel ( ⁵-C₅H₃MeBCl₃) ligand, derived from attack of BCl₃ on the ( ⁵-C₅H₄Me) moiety of the parent compound. The isolation of 2 confirms that the nucleophilic properties of organometallic anions of the type [( ⁵-C₅R₅)M(CO) _n ]^– (M = Fe, Ru, n = 2; M = Mo, W, n = 3) are not confined to the metal center, or to the carbonyl oxygens (examples of which have previously been reported) but also encompass the cyclopentadienyl ligand.     

X-ray structural and molecular mechanics investigations of cyclopentadienyl-carbonyl-triphenylphosphine-methoxyacetyl-iron (η5-C5H5)Fe(CO)(PPh3)(COCH2OMe)

The crystal and molecular structure of cyclopentadienyl-carbonyl-triphenylphosphine-methoxy-acetyl-iron (2) has been determined by X-ray. The crystals are monoclinic:P2₁/n,Z=4,=7.881(1),b=19.111(3),c=15.271(2) Å and=93.44(1)°. The structure was solved by direct methods, and refined anisotropically by full-matrix least-squares against 3419 independent reflections, givingR=0.0446. Molecular mechanics calculations reproduce satisfactorily the X-ray structure.On leave from the Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China.     

Structure of V2O5–P2O5 glasses by X-ray and neutron diffraction

The atomic structures of two V₂O₅–P₂O₅ glasses and vitreous (v-) V₂O₅ were investigated by X-ray and neutron diffraction. The V=O double bond is a common characteristic of the VO_n units that constitute the structures of the glasses. VO₅ square pyramids with elongated bonds of ~ 0.190 nm to the pyramidal base are found for the 50V₂O₅–50P₂O₅ glass. These weaker V–O bonds are balanced in V–O–P bridges by overbonded P–O bonds. The V^(IV) sites, which account for 19.7% and 35.2% of the total V sites in the 73V₂O₅–27P₂O₅ and 50V₂O₅–50P₂O₅ glasses, respectively, form similar pyramids in agreement with the structure of crystalline (VO)₂P₂O₇. The short-range structure of v-V₂O₅ and the 73V₂O₅-27P₂O₅ glass is formed of mixtures of VO₅ and VO₄ pyramids. A significant amount of V···O distances > 0.22 nm found for all glasses belong either to linkages V=O···V or to three-coordinated O sites.     

布里奇曼法制备KPb2Cl5单晶

在500 ℃高真空条件下,制备了KPb2Cl5原料,对原料进行了XRD分析,表明该方法能得到纯相的KPb2Cl5.利用改进的布里奇曼法进行了生长KPb2Cl5单晶的实验,得到了直径15 mm的原晶,并测试了晶体样品的基本红外透过性能.结果显示:不镀膜的情况下,3～20 μm的中红外波段,透过率约为80;,具有很好的红外光学性能.     

5英寸锑化铟晶片加工及表征

锑化铟(InSb)材料因其特殊的性质被广泛用于红外光电探测等领域。随着更大面阵中波红外焦平面探测器的发展以及对低成本InSb红外探测器的需求,所需的晶片材料尺寸也日益增加。本文通过采用新结构石墨托以及高精度低损伤单线切割实现了5英寸InSb晶体定向断段;采用低损伤边缘倒角技术同时优化研磨参数改善了5英寸InSb晶片研磨;通过优化贴片工序提高了5英寸InSb晶片抛光后的平整度;通过优化抛光液pH值以及配比提高了5英寸InSb晶片表面质量。同时,使用X射线晶体定向仪、原子力显微镜等测试仪器对5英寸InSb晶片的晶向及偏差、抛光表面宏观质量、几何参数、表面粗糙度、晶格质量进行了测试表征。测试结果表明,采用优化后的加工工艺制备出了高质量的5英寸InSb晶片,能够满足InSb红外探测器制备需求。