A neutron detector based on detection of the prompt gamma-radiation emitted as a result of neutron interaction with a suitable neutron absorber is described. Boron-10 loaded polyethylene is used as the neutron converter. Neutrons are thermalized in the polyethylene and are subsequently absorbed by 10B. The result of the neutron absorption is production of 7Li, in the excited state (7Li*) and an alpha-particle. This occurs for 94% of the absorbed neutrons. The 7Li* (T1/2 = 10-13 s) emits a 477.6 keV gamma-ray ("prompt" gamma-ray) after it is formed and may be detected in a gamma-ray spectroscopy system. Since the "prompt" gamma-ray peak is Doppler broadened – the recoiled 7Li* emits the gamma-ray on "fly" – it is easily distinguishable from other non-capture gamma-ray peaks. The neutron converter, 10B loaded into a polyethylene end cap placed on the standard gamma-ray spectroscopy detector, adds the neutron detection capability without impeding the system's gamma-ray spectroscopy characteristics. Results for detection of neutrons from a moderated 252Cf source are presented.
Adsorption of the herbicide terbuthylazine by a soil from the Jezreel Valley was investigated by thermo-IR-spectroscopy. The
adsorption took place mainly by the clay mineral montmorillonite. The adsorbed molecule was hydrogen bonded via the aniline
groups to water molecules which were coordinated to the exchangeable metallic cations. When the sample was thermally treated
at 115°C interlayer water was evolved, part of the herbicide decomposed and the other part became directly coordinated to
the exchangeable metallic cations. The decomposition product contained a CO group.
Authors:M. Esposito, P. Collecchi, M. Oddone, and S. Meloni
Cisplatin (CDDP) is an antineoplastic drug used in the treatment of a wide variety of tumors. This paper describes an investigation carried out on pregnant mice after intragastric or intraperitoneally treatment with CDDP from day 11 to 13 of gestation. Platinum content in different tissues, namely liver, kidney, placenta and brain, was determined at 18 day of pregnancy. Two analytical techniques were used, i.e. neutron activation analysis and atomic absorption spectroscopy. Results of both techniques are presented and discussed in terms of precision, accuracy and sensitivity. Neutron activation analysis appears to provide results better correlated with the drug treatment.
Mössbauer spectroscopy has been applied to the study of volcanic glasses and closely associated clay minerals which were carefully separated from the sediments of the Pampe Region, Córdoba, Argentina. The parameters of volcanic glass samples show the presence of a high content of Fe2+ in octahedral coordination and some Fe3+ in tetrahedral and octahedral coordination. No remarkable difference has been found with a pure volcanic glass sample taken as a reference. In the clay samples, the only clay mineral found was illite.
The spin transitions in two new cationic complexes of iron, i. e., iron bipyridine formate, [Fe/bipy/3]/HCOO/2. 5/HCOOH/ and iron bipyridine tetrafluoro borate, [Fe/bipy/3]/BF4/2. 2H2O have been studied by using Mössbauer spectroscopy. From quadrupole splitting values, at different temperatures, it has been established that both the complexes show the coexistence of both the high spin state and the low spin state at 300 K while complete transformation to low spin state occurs at 77 K. Both compounds were prepared by electrochemical technique.
Authors:Y. Saiki, M. Fukuzaki, T. Sekine, Y. Kino, and H. Kudo
Particle growing processes were investigated for technetium(VII) sulfide (Tc2S7) colloids produced in a mixture of Na2S and TcO4- solutions by laser-induced photoacoustic spectroscopy (LPAS). Analysis of the LPAS signal intensities indicated that the particle size increased in the solution with an increase of standing time, while the number of particles remained constant. It was revealed that the size of colloid particles increased by deposition of Tc2S7 on the particle surfaces, not by coagulation of colloid particles. The formation mechanism and growing process of the colloids are discussed based on the LaMer model, which deals with nucleation processes.
Authors:A. Kuno, G. Zheng, M. Matsuo, B. Takano, J. Shi, and Q. Wang
57Fe Mössbauer spectroscopy has been applied to the ultramafic rocks collected from the Jinchuan nickel deposit in China to elucidate their mineralization process. Their Mössbauer spectra consisted of two sextets ascribable to magnetite, two doublets ascribable to Fe2+ and Fe3+ in chromite, and one doublet ascribable to olivine. The closest sample to the ore body did not contain chromite and contained a doublet ascribable to pyrite and a sextet ascribable to pyrrhotite. The valence and site distribution of iron species suggested low oxygen fugacity for the formation of the Jinchuan nickel deposit.
Authors:A. Nigam, R. Tripathi, M. Jangid, and M. Chacharkar
The corrosion of mild steel as a result of interaction with various types of local natural water samples and distilled water is studied with the help of Mössbauer spectroscopy. The data are supplemented with the studies on IR and magnetic properties as and when required. Distilled water and potable water behave in almost similar fashion wherein ferrihydrite and FeOOH are observed to be the precursors of magnetite, the end corrosion product. In case of brakish water, the additional species, viz., FeCl2, FeOOH and an intermediate possibly FeOCl are accounted, and possible mechanisms are suggested.
The concentrations of Th in samples of crystalline rock from three drillcore sections were analysed independently by instrumental neutron activation analysis and by chemical separation and alpha spectroscopy. The two methods show good general agreement over an approximate concentration range of 1 to 100 ppm Th. Variations in results between the two methods are not of a systematic nature and probably arise from sample heterogeneity. The results confirm the reliability of both methods and provide a useful comparison of the standards and reference materials used. The study indicates that, in cases where Th isotopic information is not required, the simpler and more rapid neutron activation analysis provides a satisfactory method.
Authors:S. Cebulak, A. Matuszewska, and A. Langier-Kuźniarowa
The paper presents the applicability of oxyreactive thermal analysis (OTA) for the investigation of different kinds of resins
both natural (recent and fossil) and synthetic. For comparative reasons and a more precise interpretation, along with OTA
infrared spectroscopy was used as a method commonly applied for the investigation of fossil resins. The results obtained prove
that the OTA method may be very useful for diversification of different kinds of resins. The parameter most valuable for the
preliminary characteristics of resins and the evaluation of their transformation was found to be the mass loss recorded on
TG curves in three definite temperature ranges.