Magnetic properties of a new molecular-based spin-ladder system: (5IAP)2CuBr4*2H2O

We have synthesized and characterized a new spin-1/2 Heisenberg antiferromagnetic ladder: bis 5-iodo-2-aminopyridinium tetrabromocuprate(II) dihydrate. X-ray diffraction studies show the structure of the compound to consist of well isolated stacked ladders and the interaction between the Cu(2+) atoms to be due to direct Br...Br contacts. Magnetic susceptibility and magnetization studies show the compound to be in the strong-coupling limit, with the interaction along the rungs (J' ~ 13 K) much greater than the interaction along the rails (J ~ 1 K). Magnetic critical fields are observed near 8.3 T and 10.4 T, respectively, establishing the existence of the energy gap.Comment: 10 pages, 4 figures, submitted to Phys. Rev. B Figure 4 did not print. *.eps files replaced with figures.ps fil

Very high rotational frequencies and band termination in 73Br

Rotational bands in 73Br have been investigated up to spins of 65/2 using the EUROBALL III spectrometer. One of the negative-parity bands displays the highest rotational frequency 1.85 MeV reported to date in nuclei with mass number greater than 25. At high frequencies, the experimental dynamic moment of inertia for all bands decrease to very low values, indicating a loss of collectivity. The bands are described in the configuration-dependent cranked Nilsson-Strutinsky model. The calculations indicate that one of the negative-parity bands is observed up to its terminating single-particle state at spin 63/2. This result establishes the first band termination case in the A = 70 mass region.Comment: 6 pages, 6 figures, submitted to Phys. Rev. C as a Rapid Communicatio

Organically bound tritium analysis in environmental samples

Many methods allow analysing the various forms of tritium in environmental samples; however, there are no published standard methods for measuring organically bound tritium (OBT). Furthermore, there are no certified reference materials of OBT for environmental samples. In environmental samples (plants and animals), the measurement of the various tritium fractions requires extraction of the free water, often through freeze drying processes. Combustion of the dry sample is then carried out to recover organically bound tritium in the combustion water. By measuring these water fractions, the tissue-free water tritium (TFWT) and the OBT concentration can be assessed. However, these techniques are tricky and sometimes not available in all monitoring labs. Indeed, most of them measure only the TFWT fraction in food samples, such as wine or milk. Researches to promote the use of validated procedures are on-going in several countries. However, for almost all comparison exercise organisers it is difficult on a yearly basis to provide the samples and to realise the statistical treatment of the results. Therefore, to improve OBT analytical skills, an international task group devoted to the improvement of OBT analytical procedures was created to overcome these limitations. For the first exercise about 20 labs from 8 countries were registered. The samples, specially-prepared potatoes, were provided in March 2013 to each participant. Technical information and results from this first exercise are discussed here for all the labs which have realised the five replicates necessary to allow a reliable statistical treatment. From this work an optimised procedure can start to be developed to deal with OBT analysis and will guide subsequent planned OBT trials by the international group.<br/