A highly crystalline microporous hybrid organic-inorganic aluminosilicate resembling the AFI-type zeolite

ECS-14, a crystalline microporous hybrid organic-inorganic aluminosilicate, has been synthesized by using 1,4-bis-(triethoxysilyl)-benzene (BTEB) as a source of silica. Its structure contains a system of linear channels with 12-membered ring openings, running along the [001] direction, resembling the pore architecture of the AFI framework type.     

High-spin states in neutron-rich Dy isotopes populated in deep-inelastic reactions

High-spin states in neutron-rich Dy isotopes, populated in deep-inelastic processes produced by the interaction of 234 MeV ³⁷Cl ions with a ¹⁶⁰Gd target, have been studied using the highly sensitive EUROBALL IV gamma-ray detector array. The previously known level schemes for ^{159,160,161,162}Dy have been extended to significantly higher spin ( ? 30?) and the i _13/2 band crossing in ¹⁵⁹Dy has been observed for the first time. The experimental results are discussed within the framework of cranked shell model and projected shell model calculations with particular reference to the observed delayed band crossing in ¹⁶²Dy. Received: 20 October 2000 / Accepted: 16 January 2001     

Time domain bidirectional beam propagation method for second harmonic generation in multilayers

We propose a time domain bidirectional beam propagation method based on scattering operators for wide band pulse propagation in nonlinear multilayers. The reported numerical examples demonstrate the applicability of the algorithm for the analysis of temporal effects related to the process of second harmonic generation.     

A structural variability of copper(I) chloride-tetrahydrothiophene adducts crystallizing in polymeric forms and exhibiting polymorphism: The role of the solvent

The function of the solvent in the self-assembling mode of [CuCl] with tetrahydrothiophene is reported. Copper(l) chloride has been used in the form of [CuCOCl] _n , which is slightly soluble in the most common solvents, and to allow an homogeneous phase reaction. The reaction of [CuCOCl] _n with THT gave [(CuCl)₂(THT)₃] _x ,1, in CH₃OH, [(CuCl)(THT)₂] _x ,2 in THF [(CuCl)(THT)] _x ,3, in CH₂Cl₂, and [(CuCl)₃(THT)₂] _x ,4, in DME. Compound1 consists of polymeric chains of centrosymmetric Cu₂Cl₂ dinuclear units bridged by THIT molecules running parallel to the [101] axis. In the structure of2 we found polymeric layers generated from the [(CuCl)(THT)] asymmetric unit by the center of symmetry and by the twofold axis. In compound3 the structure consists of layers generated through the center of symmetry by the [(Cu₂Cl₂)(THT)₂] asymmetric unit, while4 consists of layers generated through the center of symmetry by the [(Cu₃Cl₃)(THT)₂] asymmetric unit. Crystallographic details are as [ollows:2 is monoclinic, space group P2₁/c.a=9.657(3) A,b=6.441(2) A,c=11.459(3) A,\=111.96(2)°,V=661.0(4) A³. andR=0.075;3 is monoclinic, space group P2₁/n,a=19.327(7) A,b=6.703(2) A,c=10.116(3) A,ß=103.04(3)°,V=1276.7(7) A³ andR=0.043:4 is triclinic, space group Pl,a=12.513(2) A,b=6.698(1) A,c=9.651(1) A,=91.98(1)°,\=107.86(1)°,=74.59(1)°,V=741.2(2) A³, andR=0.044.     

Excited states populated via nucleon transfer in the reaction32S +208Pb

The population strengths of excited states in nuclei produced via transfer reactions in the 185 MeV³²S +²⁰⁸Pb reaction have been investigated by heavy-ion- coincidence techniques. The cross sections extracted from the spectra, have been analyzed in the framework of the Complex WKB approximation theory.     

Spectroscopy of the 689 nm intercombination line of strontium using an extended-cavity InGaP/InGaAIP diode laser

A visible diode laser emitting at 690 nm at room temperature has been frequency-stabilized using a simple scheme based on optical feedback from a diffraction grating. The possibilities offered by these lasers for high-resolution spectroscopy are demonstrated by recording the sub-Doppler signal of the 689 nm intercombination line of strontium and resolving the hyperfine structure of the close P63 R70 (8, 4) transitions of iodine.     

Tunable frequency-controlled laser source in the near ultraviolet based on doubling of a semiconductor diode laser

Continuously tunable ultraviolet laser radiation at 397 nm was generated by doubling the output of a semiconductor diode laser. The fundamental radiation was provided by a 150 mW AlGaAs laser diode injected by a low-power AlGaAs laser diode which was frequency stabilized by optical feedback using a new scheme of a miniature external cavity. Second-harmonic generation was produced in a lithium-triborate crystal placed in a compact enhancement cavity. The fundamental radiation was used for sub-Doppler spectroscopy of the Ar I 4s ³ P ⁰ ₀–4p ¹ P ₁ transition at 795 nm; the second-harmonic radiation was used for spectroscopy of the Ca II 4² S _1/2–4² P _1/2 transition at 397 nm.