The excited states of 85Sr

High resolution γ-ray studies have shown the decay patterns of isomers of ⁸⁵Y to be very complex. A level scheme of ⁸⁵Sr is proposed from the results of γ-γ coincidence measurements. Spin and parity assignments to the levels of ⁸⁵Sr were made on the basis of log ft values, nuclear reaction data and γ-ray branchings. The level scheme is discussed within the theoretical framework of $\text{n(}\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}\text{)}{}^{\mathrm{?3}}$ cluster properties.     

New157Lu isomer

The new low spin isomeric state of¹⁵⁷Lu (probably s_1/2) with T_1/2=9.6(8) s and E_±=4925(5) keV was found in experiments on YASNAPP-2 ISOL facility. The previously known isomer of¹⁵⁷Lu (T_1/2=4.75(10) s,_±=4998(5) keV) lies 32(2) keV higher than the new one.On leave from the M. Curie-Sklodowska University, Lublin, Poland     

Production of light nuclei in the reactions of protons with separated tin isotopes

The cross sections for the production of ⁷Be, ²²Na, ²⁴Na, ²⁸Mg, ³⁸S, ³⁸Cl, and ³⁹Cl nuclei from ¹¹²Sn, ¹¹⁸Sn, ¹²⁰Sn, and ¹²⁴Sn targets irradiated with 0.6-, 1.0-, and 8.1-GeV protons were measured by the method of induced activity. In analyzing resulting data, it was established that the above nuclei are produced in the fragmentation process and that the reaction cross section is a power-law function of the mass and charge numbers of fragmentation products. A strong dependence of the reaction cross section on the nucleonic composition of the targets and of the products is observed. The measured cross sections, together with data available in the literature, are discussed within various assumptions.     

Silicon-containing polymers for non-linear optics

A variety of novel poly[ethynediyl-arylidene-ethynediyl-silylene]s (PEAES), including those containing hypercoordinate silicon atom as well as donor and acceptor groups, has been synthesized. The presence of hypercoordinate silicon favours high values of fast Kerr-type non-linearities, and the incorporation of amide groups gives rise to good optical quality nanocomposites in a silica matrix. The inorganic-organic hybrid sol-gel film incorporating 5–14 mass% of the polymer containing pentacoordinate silicon showed Re ⁽³⁾ = –9.5 ×10^–11 esu. The predominant rôle of the electron nonlinear mechanism has been demonstrated by using test beams with linear and circular polarizations. The photorefractive properties of composites based on PEAES as optical chromophores, poly(9-vinylcarbazole) as photoconductor, N-ethylcarbazole and phenyltrimethoxysilane as plasticizer, and fullerenes as charge generators have been investigated. The nonlinear optical effects, including four-wave mixing and two-beam coupling were studied at 633 nm without preliminary electric poling. The photorefractive origin of the refractive index changes was confirmed by the high two-beam gain under an externally applied electric field. Refractive index gratings affording two-beam gain can also be written under zero field conditions. To explain this unique property of the materials it is suggested that chromophore orientation asymmetry arises either during film formation or is induced by the longitudinal intensity gradient.