Reactions of 14N and 16O ions with light nuclei at Elab = 16–58 MeV

Yield curves for formation of ⁷Be and other radio-nuclides from bombardment of C, Al and Si targets with 16–58 MeV ¹⁴N and ¹⁶O ions were measured. The ⁷Be yields disagree by several orders of magnitude with Hauser-Feshbach and transition-state predictions. The other yields are in order-of-magnitude agreement with nucleon and/or α-particle evapolation calculations.     

Molecular recognition in a thermoplastic elastomer

Selective incorporation of bisurea guests in thermoplastic elastomers with poly(tetrahydrofuran) soft blocks and bisurea containing hard blocks is observed when the distances between the urea groups of host and guest match. The incorporation leads to significant modulation of mechanical properties. With bisurea-functionalized dyes as guests, a strong difference in extractability by detergent solution was shown between dyes differing by just one methylene unit between urea groups. Upon elongation of elastomer films, strong differences in alignability of matching and nonmatching dyes were observed.     

Non-ionic polythiophenes: a non-aggregating folded structure in water

The non-aggregating nature of a water-soluble pi-conjugated polythiophene has been characterised by concentration independent thermal denaturing.     

Critical temperatures of triangular Ising lattice with small second neighbor interaction

The next-nearest neighbor correlation function for isotropic triangular Ising system has been evaluated. This function is used to determine the shifts in the critical temperatures of ferromagnetic and antiferromagnetic triangular lattice after introduction of a small next-nearest neighbor interaction in zero field.     

Re-investigation of the166Yb→166Tm Decay

The decay of¹⁶⁶Yb has been investigated with high-resolution Ge(Li) detectors. The intensity of any γ ray other than that at 82.29 keV is less than 0.3% per decay. The total decay energy was redetermined asQ=215 _?18 ⁺³³ keV. An upper limitF _w< 150 was determined for the hindrance factor of theF-forbidden 82.29 keV transition.     

Alkylsilver(I) induced 1,5-substitution in functionally conjugated enynes. a novel route to cumulated trienes

Functionally conjugated enynes, H₂CC(R¹)CCCR²R₃OS(O)Me, undergo 1,5-substitution with alkylsilver(I) reagents, RAGG ☆ 3 LiBr. The purity of the produced alkylated butatrienes, RCH₂C(R¹)CCCR²R³ depends on the nature of R in RAg ☆ 3 LiBr and on the substituents R¹, R² and R³ in the substrate.     

Loading Stark-decelerated molecules into electrostatic quadrupole traps

Beams of neutral polar molecules in a low-field seeking quantum state can be slowed down using a Stark decelerator, and can subsequently be loaded and confined in electrostatic quadrupole traps. The efficiency of the trap loading process is determined by the ability to couple the decelerated packet of molecules into the trap without loss of molecules and without heating. We discuss the inherent difficulties to obtain ideal trap loading, and describe and compare different trap loading strategies. A new “split-endcap” quadrupole trap design is presented that enables improved trap loading efficiencies. This is experimentally verified by comparing the trapping of OH radicals using the conventional and the new quadrupole trap designs.     

Highly fluorescent crystalline and liquid crystalline columnar phases of pyrene-based structures

A concept for highly ordered solid-state structures with bright fluorescence is proposed: liquid crystals based on tetraethynylpyrene chromophores, where the rigid core is functionalized with flexible, promesogenic alkoxy chains. The synthesis of this novel material is presented. The thermotropic properties are studied by means of differential scanning calorimetry (DSC), cross-polarized optical microscopy (POM), and X-ray diffraction. The mesogen possesses an enantiotropic Col(h) phase over a large temperature range before clearing. The material is highly fluorescent in solution and, most remarkably, in the condensed state, with a broad, strongly red shifted emission. Fluorescence quantum yields (Phi(F)) have been determined to be 70% in dichloromethane solution and 62% in the solid state. Concentration- and temperature-dependent absorption and emission studies as well as quantum-chemical calculations on isolated molecules and dimers are used to clarify the type of intermolecular interactions present as well as their influence on the fluorescence quantum yield and spectral properties of the material. The high luminescence efficiency in the solid state is ascribed to rotated chromophores, leading to an optically allowed lowest optical transition.