Dielectric relaxation losses in lead chloride and lead bromide: Localized dipoles

A further analysis of previous reported measurements of dielectric relaxation losses in lead chloride and lead bromide crystals shows that the dipoles may occupy several energetically different positions, giving rise to localization of the dipoles and anomalous behaviour of the susceptibility. This energy difference is determined. Inspection of the crystal structure shows that the anion vacancy, being the mobile part of the dipole (which is an associate like (Me_Pb·V_X)^x or (O_X·V_X)^x where X = Cl, Br), may jump indeed between halide ion sites with different coordination number.A comparison between the dipole concentration as calculated from the observed losses and the associate concentration as estimated from ionic conductivity experiments leads to the conclusion that local field corrections in the calculations are important.     

Separation of sodium and potassium by ion-exchange on cellulose phosphate

(24)Na and (42)K can be separated by ion-exchange chromatography with 80% methanol-2M hydrochloric acid on an 80 x 6mm column of cellulose phosphate. On cellulose phosphate paper the R(f) values are 0.63 for Na and 0.40 for K.     

Trace analysis by microwave excitation of sealed samples-I: preliminary investigations

An important limitation to the sensitivity of analytical methods using atomic spectroscopy is the short residence-time of the atoms in the light-path. The possibility has been studied of sealing the samples in a quartz tube where they are forced to emit light by microwave excitation. The detection of amounts below one ng in a volume of 0.5 ml seems possible.     

Dynamische Betrachtungen von Kontakt winkelmessungen an adsorbierten Proteinschichten

Ohne Zusammenfassung     

The addition of methylborylene to acetylenes

The synthesis of alkyl-substituted 1,4-dimethyl-1,4-diboracyclohexa-2,5-dienes from dialkylacetylenes and the system C₈K/MeBBr₂ is described.     

Transferability of dipole moment derivatives: Calculation of absolute rotational contributions for symmetrical molecules

It is shown that Polo's method for the calculation of the D^?1 and G^?1 matrices can be extended to the calculation of the absolute rotational contributions involved in the molecular dipole moment derivatives in terms of symmetry coordinates. The method applies to both stretching and bending modes. The method is outlined for AB₃ (C_3v) molecules.     

Synthesis of quinoline and benzo[b]thiophene derivatives by ring annelation of pyridines and thiophenes

Selected ortho-disubstituted pyridines and thiopenes react with Michael acceptors to give functionalized quinolines or benzo[b]thiopenes, respectively.     

Measurements of the second-sound velocity in dilute 3He4He mixtures

A Helmholtz resonator was used to measure the velocity of second sound in dilute solutions of ³He in ⁴He. The results are compared with values reported by Brubaker et al. and de Voogt et al.