A study of particle-vibration multiplets in 203Tl using the 205Tl(p,t)203Tl, 208Pb(p,t)206Pb and 206Pb(p,t)204Pb reactions

The ²⁰⁵Tl(p, t)²⁰³Tl reaction has been used at 26.2 MeV to obtain additional information on the particle-vibration multiplets in ²⁰³Tl. Enhancement factors for the L = 0 and L = 2 transitions to the lower excited states of ²⁰³Tl were well accounted for by using enhancement factors from the ²⁰⁶Pb(p, t)²⁰⁴Pb reaction and the wave functions from the intermediate coupling calculations of Covello and Sartoris. Additional data on the ²⁰⁸Pb(p, t)²⁰⁶Pb reaction at 26.2 MeV were used along with data at other energies to examine the energy dependence of the zero-range enhancement factors.     

Intercalation of Toluidines into α-Zirconium Hydrogenphosphate

Intercalates of o-, m-, and p-toluidine into α-Zr(HPO₄)₂ · H₂O were prepared and characterized by powder X-ray diffraction, thermogravimetric analysis and infrared spectroscopy. As follows from IR, toludine molecules are protonated in the interlayer space. Toluidine molecules are arranged in a bimolecular way in the intercalates containing more than 1.5 toluidine molecules per Zr atom. On the other hand, a monolayer of the toluidine molecules is supposed in the intercalates with less than one toluidine molecule per Zr atom.     

Low-lying excited states of106Ag studied with the103Rh (α,nγ)106Ag and104Pd (α,pnγ)106Ag Reactions

The level scheme of¹⁰⁶Ag has been studied using the¹⁰³Rh(α,nγ)¹⁰⁶Ag and¹⁰⁴Pd(α,pnγ)¹⁰⁶Ag Reactions. The experimental information is taken fromγ-ray coincidence data using Ge(Li)-Ge(Li) and HPGe-planar Ge(Li) configurations andγ-ray angular distributions. With these measurements 126 γ rays have been assigned to¹⁰⁶Ag with 116 deexciting 78 states below 2.26 MeV in excitation. The location of the 8.4-day 6⁺ isomer is established at 89.63±0.09 keV. Many of the low-lying states are interpreted in terms of a slightly deformed rotor model.     

The (p,nγ) reaction on Al and Si

The reactions ²⁷Al(p, n γ) ²⁷Si and ²⁸Si(p, n γ)²⁸P have been studied at E_p = 16 and 23 MeV, respectively, with a Ge(Li) detector in coincidence with a neutron detector. In ²⁷Si, two new γ-tran- sitions were detected and accurate excitation energies were determined. In ²⁸P, the γ-decay scheme was studied for the first time and new levels were located at 879 and 1602 keV excitation energy. For both nuclei the γ-ray spectra were supplemented by neutron time-of-flight spectra. The excitation energies are compared with those of the analogue nuclei and with the predictions from Coulomb displacement calculations.     

On-line delta(18)O measurement of organic and inorganic substances

A method for the automated sample conversion and on-line oxygen isotope ratio (delta(18)O) determination for organic and inorganic substances is presented. The samples are pyrolytically decomposed at 1400 degrees C in the presence of nickelized graphite. With the system presented organic as well as inorganic samples such as nitrates, sulphates and phosphates of 50-100 &mgr;g O can be analyzed for their delta(18)O values with a standard deviation usually better than 0.5 per thousand. Additionally, carbon isotope ratios of organic substances and nitrogen isotope ratios of inorganic nitrogenous compounds are available in the same sample run. Data for international and some inter-laboratory reference materials are presented to show the accuracy and reliability of the method. The effect of some additives on the CO yield was checked for substances which do not pyrolyze completely. Copyright 1999 John Wiley & Sons, Ltd.     

The (3He,t) reaction on 24Mg and 28Si

The (³He, t) charge exchange reaction on ²⁴Mg and ²⁸Si has been studied at 38.5 MeV. The angular distributions provide a number of new spin assignments in ²⁴Al and ²⁸P. A two-step excitation through intermediate α-particle channels was used to predict the ²⁴Al cross sections. The fits are fair in shape, but about a factor of three too large when a perfect overlap of initial and final shapes is assumed. The data to three 1⁺ states of ²⁸P are compared to the known electromagnetic reduced transition rate B(M1) to the analog states in ²⁸Si.     

Energy dependence of π+ induced two- and four-nucleon removal

De-excitation γ-rays have been detected from nuclear states following positive pion induced two-nucleon removal from ¹²C and four-nucleon removal from ¹⁶O. Excitation functions for population of discrete states were obtained for positive pions of 75, 125, 150, 200, 225, 250 and 290 MeV. The pion-nucleon (3, 3) resonance is not reflected in the cross sections for either reaction. Implications of the observed energy dependence are discussed.     

The 33 and 43 MeV (3He, xnγ) exclusive reactions on targets from Zr to Pb

Exclusive neutron spectra for neutron multiplicities x = 3, 4 and 5 have been obtained using the 33 and 43 MeV (³He, xnγ) reactions on targets of Zr, Pd, Sn, Nd, Pt, Au, and Pb. The exclusive spectral shapes vary systematically with the energy available for neutron decay in the initial or precompound nucleus. The (³He, xnγ) reaction differs from the (αxnγ) reaction at the same beam energy per nucleon in its dependence on available energy, target, and incident angular momentum.     

Experimental, Theoretical and Biological Activity Study on the Acyl-Substituted Benzo-18-crown-6, Dibenzo-18-crown-6 and Dibenzo-24-crown-8

Hexadecanoyl, dihexadecanoyl, dioctadecaneoyl, di-10-undecenoyl, and dicis-9-octadecenoyl derivatives of benzo[18]crown-6, dibenzo[18]crown-6 and dibenzo[24]-8 were synthesized by the condensation of carboxylic acids (palmitic, stearic, oleic and undecenoic acid) with benzo and dibenzo crown ethers in the presence of zinc chloride. The extraction equilibrium constants of such macrocyclic ethers with long side chains were estimated using chloroform/water and dichloromethane/water membranes transfer of Na-PAR (4-(2-pyridylazo)-resorcinol mono sodium monohydrate) with UV–Vis spectroscopy. It was found that they were in the range of 10.88–11.71 in dichloromethane and 8.04–11.77 in chloroform. These results actually show that the Na+ binding effect of macrocyclic ethers depends on the type and the length of side chains. The geometrical properties of the molecules were studied employing semi-empirical calculations by simulated annealing technique. The frontier molecular orbital energies and dipole moments were also examined. The biological activity results showed that the synthesized crown ethers have no activity against the studied microorganisms.