Ildikó Harsányi

Hydration of ions in aqueous RbCl solutions

Structural studies have been carried out on aqueous rubidium chloride solutions at three concentrations. Particle configurations consistent with neutron and x-ray diffraction data were obtained by reverse Monte Carlo modelling. By applying several coordination constraints, the generally accepted concept concerning the hydration of chloride ions could be tested in detail. The structural models generated may be made consistent with Cl(-) ions surrounded by six neighbouring water molecules, of which only three can connect to the ion via straight Cl...H-O (hydrogen bond) angles.

On the structure of aqueous hydrogen chloride solutions

Neutron and x-ray diffraction data taken on aqueous HCl/DCl solutions at different concentrations (Triolo and Narten 1975 J. Chem. Phys. 63 3624) have been analysed by means of the reverse Monte Carlo modelling technique. Partial radial distribution functions, numbers of neighbours and cosine distributions of bond angles have been calculated from the resulting particle configurations. Based on these results, the original interpretation of experimental data must be altered; Cl-H/D correlations, for instance, seem to have a more important role than had been thought previously.

High pressure metaophiolite polished stone implements found in Hungary

Good quality high pressure (HP) metaophiolite rock types (e.g. Na-pyroxenite/jade, eclogite) suitable for making prehistoric polished stone implements were unknown among Hungarian findings for a long time. Nowadays they are still among the rarest types of polished stone implements found in Hungary in the respect of raw material. After the first discovery of Neolithic stone tools made of HP metaophiolites in the records of Hungarian archaeological assemblages, detailed petrological investigations of large stone implement collections revealed their presence in a relatively large number. According to our current knowledge, 25 HP metaophiolite stone implements are known as found in Hungary. Unfortunately, most of them are stray finds, but 11 pieces from four localities have a known archaeological context. They were mainly located in Transdanubia (except for one piece from Tiszántúl) and are mostly attributable to the Late Neolithic Lengyel Culture and secondarily to the Late Neolithic Tisza Culture. In this study, we used only non-destructive analytical methods (macroscopic observation, magnetic susceptibility measurements, non-destructive SEM-EDX, and Prompt Gamma Activation Analysis). As a result of this study, the prehistoric stone implements were classified into raw material types. Based on our data, the high pressure-low temperature (HP-LT) metaophiolite stone implements found in Hungary probably originated from the same raw material sources as the Italian HP-LT metaophiolite stone tools (sourcing from North-western Italy). According to the literature on the topic, both primary (Western Alps in the vicinity of the Monviso in Piedmont or the Voltri Massif in Liguria) and secondary occurrences (in Quaternary deposits of the rivers Po, Staffora and Curone) are potential sources. These analyses confirmed the existence of long-distance trade routes connecting the Po Valley and its vicinity with the Carpathian Basin during the Vth Millennium BC.

X-ray and neutron-based non-invasive analysis of prehistoric stone artefacts: a contribution to understand mobility and interaction networks

Carbonate-rich archaeological artefacts are difficult to identify and correlate between them and with raw materials of such heterogeneous geological sources, especially when only non-invasive analysis is possible. A novel combination of X-ray and neutron-based non-invasive analysis is implemented and used for the first time to study prehistoric stone idols and vessels, contributing to culture identity, mobility and interaction in the recent Prehistory of Southern Iberia. Elemental composition was obtained by prompt gamma activation analysis (PGAA) and external beam particle-induced x-ray emission (PIXE); homogeneity of the stone artefacts and the presence/absence of internal fractures were obtained by neutron radiography (NR). These atomic and nuclear techniques, simultaneously used for complementary chemical information, have been demonstrated to be of great value as they provide non-destructive compositional information avoiding sample preparation, crucial in so singular and rare objects. The obtained results, especially of PGAA, are very promising and useful in general assessments of provenance. The stone artefacts show signs of both nearby and long-distance procurement, as well as of unknown attribution.

Acidic properties of aqueous phosphoric acid solutions: a microscopic view

We report on new neutron and x-ray diffraction data on D2O:D3PO4 solutions at two concentrations, 1:1 and 3:1. The experimental datasets were modelled simultaneously by the reverse Monte Carlo (RMC) method. From the resulting models, partial radial distribution functions (prdf) and coordination numbers were obtained. The acidity was found to decrease with increasing D3PO4 concentration. The ratio of dissociated acidic protons was estimated by dedicated simulation runs using average coordination number constraints. It was found that in the saturated solution the ratio of dissociated protons cannot exceed 20%.