Effect of a magnetic flux line on the quantum beats in the Henon-Heiles level density

The quantum density of states of the Henon-Heiles potential displays a pronounced beating pattern. This has been explained by the interference of three isolated classical periodic orbits with nearby actions and periods. A singular magnetic flux line, passing through the origin, drastically alters the beats even though the classical Lagrangian equations of motion remain unchanged. Some of the changes can be easily understood in terms of the Aharonov-Bohm effect. However, we find that the standard periodic orbit theory does not reproduce the diffraction-like quantum effects on those classical orbits which intersect the singular flux line, and argue that corrections of relative order variant Planck's over 2pi are necessary to describe these effects. We also discuss the changes in the distribution of nearest-neighbor spacings in the eigenvalue spectrum, brought about by the flux line. (c) 1995 American Institute of Physics.     

The nature of the C-defects in nickel and their rôle in the interpretation of radiation damage in metals

In previous Perturbed-Angular-Correlation (PAC) studies of the - emission of ¹¹¹In probe nuclei in cold-worked or particle-irradiated nickel, it has been found that thermal annealing in the temperature regime of recovery stage III leads to the formation of so-called C-defects (Cubic defects). This is indicated by the occurrence of a new frequency of about 80 Mrad/s, in addition to the frequency (200 Mrad/s) that is due to ¹¹¹In on substitutional sites. Obviously, the C-defects are complexes consisting of ¹¹¹In and the intrinsic point-defect species that migrates freely in recovery stage III. Therefore, they have played an important rôle in the long-standing controversy on whether the recovery-stage-III defects are vacancies (one-interstitial model) or self-interstitials (two-interstitial model). The present paper reports on a novel experimental effort to reveal the nature of the C-defects by combining PAC studies on nickel samples differently pretreated in a systematic way, investigations of the Extended X-ray Absorption Fine Structure (EXAFS) on In-doped nickel, and measurements of the decay rate of ¹¹¹In nuclei in the Electron-Capture-Induced Decay (ECID). On the basis of the results of these experiments it is concluded that the defects trapped by substitutional ¹¹¹In atoms (In_s) in recovery stage III are self-interstitials (I), as expected according to the two-interstitial model. Moreover, there is evidence that the C-defects are In interstitials on tetrahedral sites (In_i) that form exclusively in the vicinity of the specimen surface from In_s – I pairs via the reaction In_s+I In_i.     

Emission spectra of the radical cations of hexa-, penta-, tetra-, and tri-fluorobenzenes

Emission spectra of the radical cations of the title fluorobenzenes were excited in the gaseous phase by electron impact. The spectra, vibrational fine structure discernible and the threshold energy of the emission are discussed in relation to the photoelectron spectra of the fluorobenzenes.     

Development of pork fat reference material for OCPs BCR-CRM 430

Summary A pork fat sample was prepared and tested as candidate reference material for 10 organochlorine pesticides and metabolites (OCPs): hexachlorobenzene, -, - and -HCH, -heptachlor epoxide, dieldrin, endrin, p,p'-DDT, p,p'-TDE and p,p'-DDE. Preparation and testing for homogeneity and stability of the OCPs in the pork fat are discussed. The coefficient of variation of pesticide determinations carried out to test the between-ampoule homogeneity ranged from 2.4–5.8% and was found to be very similar to that for the analytical method (2.5–4.9%). This means that the homogeneity is very good. Stability data over 12 months do not show any trends that suggest lack of stability.     

Organische Phorsphorverbindungen XXXV. Die α-Aminoalkylierung von elementarem weissem Phosphor und von Biphosphinen. Darstellung und Reaktionen von dialkylaminomethyl-substituierten tertiären Phosphinoxiden [1]

Further examples of the α-aminoalkylation of white phosphorus and of a biphosphine are reported. The reaction is described using C-methyl piperidines, methylamine, ethylamine or propylamine as the amine component, and formaldehyde or benzaldehyde as the carbonyl component. The reaction mechanism has been clarified. Furthermore the direct synthesis of the diethylamine salt of phosphorous acid is reported. In addition, some physical and chemical properties of tris (dialkylamino-methyl)-phosphine oxides are given and their coordination compounds with nickel halides are described.