He I ultraviolet photoelectron spectroscopy of benzene and pyridine in supersonic molecular beams using photoelectron imaging

We performed He I ultraviolet photoelectron spectroscopy (UPS) of jet-cooled aromatic molecules using a newly developed photoelectron imaging (PEI) spectrometer. The PEI spectrometer can measure photoelectron spectra and photoelectron angular distributions at a considerably higher efficiency than a conventional spectrometer that uses a hemispherical energy analyzer. One technical problem with PEI is its relatively high susceptibility to background electrons generated by scattered He I radiation. To reduce this problem, we designed a new electrostatic lens that intercepts background photoelectrons emitted from the repeller plate toward the imaging detector. An energy resolution (ΔE/E) of 0.735% at E = 5.461 eV is demonstrated with He I radiation. The energy resolution is limited by the size of the ionization region. Trajectory calculations indicate that the system is capable of achieving an energy resolution of 0.04% with a laser if the imaging resolution is not limited. Experimental results are presented for jet-cooled benzene and pyridine, and they are compared with results in the literature.     

Excited‐State Dynamics of CS2 Studied by Photoelectron Imaging with a Time Resolution of 22 fs

The ultrafast dynamics of CS₂ in the ¹B₂(¹Σ_u⁺) state was studied by photoelectron imaging with a time resolution of 22 fs. The photoelectron signal intensity exhibited clear vibrational quantum beats due to wave packet motion. The signal intensity decayed with a lifetime of about 400 fs. This decay was preceded by a lag of around 30 fs, which was considered to correspond to the time for a vibrational wave packet to propagate from the Franck–Condon region to the region where predissociation occurred. The photoelectron angular distribution remained constant when the pump–probe delay time was varied. Consequently, variation of the electronic character caused by the vibrational wave packet motion was not identified within the accuracy of our measurements.     

Investigation of the ηη system in π − p interactions at a momentum of 32.5 GeV/c at the GAMS-4π spectrometer

The ηη system produced in charge-exchange π ^? p interaction at a momentum of 32.5 GeV/c is studied in an experiment performed with the GAMS-4π spectrometer at the 70-GeV accelerator of the Institute for High-Energy Physics (IHEP, Protvino). A partial-wave analysis is performed in the mass range between 1.1 and 3.9 GeV for ?t <0.2 (GeV/c)², S, D, G, and J waves being taken into account in this analysis. The S wave has a complicated structure, displaying peaks at about 1.5 and 1.7 GeV. These peaks are associated with the f ₀(1500) and f ₀(1710) mesons. One of the solutions (preferable one) involves the f ₀(2200) and f ₂(1950) resonances. The mass region above 2.4 GeV is dominated by the G wave. A broad state of mass about 3 GeV and width 0.7 GeV is found in the J wave. The parameters of the resonances in question and their production cross sections are measured.     

Transport of calcium and potassium ions in opposite directions in a liquid membrane system

A new type of 18-crown-6 derivative having two carboxylic acids on the side arms transported calcium and potassium ions in opposite directions across a dichloromethane membrane by pH control. Calcium and potassium ions were concentrated in the acidic and the basic phases, respectively. The presence of picrate ion in the acidic phase plays an important role in the transport of potassium ion from the acidic to the basic phase.     

Partial-wave analysis of the ωπ0-system at high masses

A partial-wave analysis of the ω ωπ⁰-system produced in the π^- p→ωπ⁰ n reaction at 38 GeV/c beam momentum has been performed. A new 5^?- meson state,ρ ₅(22350), with a massM=2330±35 MeV and a width Γ=400±100 MeV, is observed. The analysis also confirms the 1^?- ρ(2150) meson, a radial-orbital excitation of the ρ(770), observed earlier by the GAMS Collaboration.     

Synthesis and evaluation of 3-methyl-4-oxo-6-phenyl-4,5,6,7-tetrahydrobenzofuran-2-carboxylic acid ethyl ester derivatives as potent antitumor agents

For the construction of new combinatorial libraries, a lead compound was created by replacing the core structure of a hit compound discovered by screening for cytotoxic agents against a tumorigenic cell line. The newly designed compound maintained biological activity and allowed alternative library construction for antitumor drugs.     

A peptide motif recognizing a polymer stereoregularity

A combinatorial phage display method was applied to films composed of a stereoregular polymer of methacrylates. The phage clones with selective affinity for isotactic (it) poly(methyl methacrylate) (PMMA) were isolated. Greater amounts of the phage clones bound to it-PMMA, compared to other stereoregular PMMAs. The phage expressing ELWRPTR most strongly bound to the polymer, and the selectivity was also the best. The peptide motif essential for the specific interaction with the stereoregular polymer was revealed.     

Effect of Sn and Nb on generalized stacking fault energy surfaces in zirconium and gamma hydride habit planes

We have investigated the effects of Sn and Nb on dislocation properties in a Zr lattice to elucidate the role of these alloying elements in hydride nucleation processes. According to experimental observations, γ-hydride habit planes are close to the prismatic plane in pure Zr and close to the basal plane in Zircaloy. Dislocation loops are observed around hydride precipitates, implying they play a part in hydride formation. Our ab initio generalized stacking-fault energy calculations showed remarkable effects of Sn on unstable-stacking energy and stacking-fault energy: these parameters for basal slip were considerably reduced while those for prismatic slip were increased in the presence of Sn. These results suggest selective stabilization and enhancement of dislocation spreading in the basal plane, promoting possible elementary processes of hydride precipitation with basal habit plane, i.e. screw-dislocation spreading and edge-dislocation emission in the basal plane.     

Sonochemical immobilization of noble metal nanoparticles on the surface of maghemite: mechanism and morphological control of the products

Aqueous sample solutions containing noble metal ions (HAuCl₄, Na₂PdCl₄, H₂PtCl₆), polyethyleneglycol monostearate, and magnetic maghemite nanoparticles were irradiated with high power ultrasound. Analyses of the products showed that noble metal ions were reduced by the effects of ultrasound, and the formed noble metal nanoparticles were uniformly immobilized on the surface of the maghemite. The present “one pot process” significantly simplifies the immobilization of noble metal nanoparticles on the surface of supports, compared with the conventional impregnation method. The average diameter of immobilized Au was 7–13 nm, and the diameters of Pd and Pt were several nm. The diameters depended upon the concentration of polyethyleneglycol monostearate and the concentration of noble metal ions, but not upon the maghemite concentration, indicating the possibility of the morphological controls of the products by adjusting these preparation conditions. The measurements of the average diameters and the numbers of immobilized Au nanoparticles obtained under various conditions suggest that the nucleation of Au does not occur on the surface of maghemite, but it might occur in the homogeneous bulk solution.