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At the Stable Isotope Laboratory at Rijeka University (SILab Rijeka) we monitor the stable isotope composition (δ18O, δ2H) of precipitation in Croatia. Our data base contains about 50 stations distributed all around the country. Their different latitudes, longitudes and altitudes give information in great detail, including the influence of the topographic structure on the precipitation in this south-eastern part of Europe, as well as the complex interplay of the different climate conditions in the area. Within a few hundred kilometers, the stable isotope values display a significant change from the maritime character in the South (mean δ18O around –6 to –8 ‰) to the continental behavior in the North (mean δ18O around –8 to -11 ‰). In addition, depending on the location, the mean δ18O values vary with altitude at a rate between approximately −0.2‰ /100m to −0.4‰ /100m, respectively. Particular attention is given to the correlation between δ18O and δ2H (the Local Meteoric Water Line, LMWL), as well as the d-excess d = δ2H − 8٠δ18O.

Several karst springs in the Gacka area of Croatia were studied using environmental tracers (stable isotopes (18O, 2H), tritium (3H), chlorofluorocarbons (CFCs) and noble gases (3He, 4He, Ar, Ne, Kr, Xe)). They provided valuable information regarding the mean residence time and age distribution of the spring waters. The variation of the precipitation’s isotopic signal in spring discharge indicates mixing of waters with different transit times. Comparison of CFC and 3H/3He data reveals that during the dry weather period some space in the karst groundwater systems is not filled with water. The results show that compared to single-tracer studies, multitracer techniques may allow a better understanding and characterization of the system.

Speleothems are used in climate change studies. In order to reconstruct palaeo-environmental settings on the eastern Adriatic coast during the Late Pleistocene and Holocene, stable isotope analyses of carbonate speleothems, of rain and of drip water in the Modrič Cave were conducted. In this investigation an estimate of the equilibrium isotope condition during the formation of paleothems is required. The cave is situated 120 m from the Adriatic coast in the Southern part of Croatia at an altitude of 32 m a.s.l. Due to its position of the SW slope of the Dinaric mountain range, the Mediterranean climatic influence (humid, hot summers, moderate winters) is dominant. The precipitation is about 1200 mm/a.

Students interested in the GLOBE program collect and determine amounts of daily precipitation, measure air temperature and send monthly averaged water samples to the Stable Isotope Laboratory (SILab)at Rijeka University. At the SILab, samples are analysed for their conductivity, pH, dissolved oxygen, salinity and isotopic composition in regards to delta2H and delta18O. The delta-values are determined in a Thermo-Finnigan DeltaplusXP mass spectrometer. The first results of this projects already demonstarte the complexity of the meteorological situation in the country, it is appropriate to briefly look at the location of the country and corresponding implications.

The water management in Croatia is a national priority since about 50% of the country consists of karst. It is thus of vital interest to have a complete as possible knowledge of all related factors, including the precipitation as the input into the water system. Besides meteorological data, isotopic tracers are important tools to understand and quantify this complex problem. Very little information exists, however, about the isotopic composition of precipitation in Croatia. Therefore, we propose to collect precipitation through the GLOBE program in order to establish an atlas of the isotopic composition of precipitation for as wide an area of Croatia as possible. GLOBE (Global Learning and Observations to Benefit the Environment) is a worldwide primary and secondary school-based science and education program. In Croatia, about 100 schools are involved in GLOBE, and about 25 contribute in this nationwide collection of precipitation. These samples are then sent to and analysed in the Stable Isotope Laboratory at Rijeka University (SILab Rijeka). First results will be shown at the Conference.

Na Sveučilištu u Rijeci osnovan je prvi hrvatski laboratorij za masenu spektroskopiju stabilnih izotopa s ciljem istraživanja krškog područja te proučavanja procesa u hidrološkim, hidrogeološkim i meteorološkim ciklusima. U radu su izneseni preliminarni rezultati mjerenja δ 18O u vodi za tri izvora rijeke Gacke. Interpretaciju rezultata mjerenja upotpunjuju podaci iz Državnog hidrometeorološkog zavoda.

A large fraction of Croatia (nearly 50%) consists of Karst, and the study of related hydrogeological problems are high on the country’ s priority list. Therefore, Croatia’ s first laboratory for stable isotope mass spectrometry has been set up at Rijeka University. It features a Delta+XP , fitted with a Gas Bench (incl. a 96-position autosampler, generally used for δ 18O analysis in water and carbonates) and a Dual Inlet. Addition of an Equilibration Unit is planned for high-precision δ D measurement. Several home standards (ca. 40 l each) covering a δ 18O range between – 1.6 and -26, 4 have been calibrated against standardized samples. First δ 18O measurements serve as examples for the application of IRMS data to determine the dominant recharge areas of Gacka river and Vrana lake. We gratefully acknowledge supported by the MZOS in project 0062011 and by the IAEA in project CRO/8/006.

We present a quantum statistical treatment of the Giant Magnetoresistance (GMR) in multilayers with an arbitrary number of layers and arbitrary angles between the magnetization vectors in the magnetic layers. The intrinsic potential and the exchange splitting of the conducting electron band is taken into account. The developed approach was successfully applied to the description of the GMR in combination multilayers.

Coulomb fragmentation processes in collisions of Kr8+ ions with nitrogen molecules were studied at projectile energies between 19 and 171 eV/u. At low impact energies (less than or similar to50 eV/u) and small impact parameters, the electron distribution of the fragmenting molecular N-2(q+) ion becomes strongly polarized. This is due to the presence of the slow highly charged projectile during the fragmentation process. Microscopic calculations simultaneously incorporating electron transfer and molecular dissociation give insight into the dynamics of this newly found polarization effect.

We report the first measurement of the kinetic energy release distributions of multiply charged oxygen ions produced in collisions of O-2 molecules with 5.9 MeV/amu Xe18+ and Xe43+ ions. The Slow Oq+ ions generated in the collision are detected in coincidence by a time- and position sensitive multiparticle detector. An analysis of correlated momenta of molecular fragments provides the kinetic energy release distribution for various reaction pairs O-2 --> O-q1+Oq2+ with a total charge up to q = q(1) + q(2) = 11. The position of the maximum and the width of the distributions are well described by the recently suggested Average Bunch Statistical (ABS) model.

We have Studied the ionization and fragmentation Of C-60 in collisions with protons and deuterons at impact energies of 50-300 keV. The time-of-flight spectra of all fragment ions were measured in coincidence with one of the emitted electrons. The cross sections of multiple ionization as well as relative yields of even-mass fullerene-type ions of various charges are deduced from experimental spectra. A theoretical model based on a statistical approach is developed for the explanation of the experimental data. The model describes the p +C-60 collision as proceeding in three steps: (i) energy deposition by the projectile, (ii) emission of prompt electrons, and (iii) C-2 evaporation and delayed electron emission. The observed distribution of fragment fullerenes indicates that the delayed electron emission is an essential part of the process and that it occurs before the equilibration is achieved.

We have studied energy transfer, fragmentation and ionization in collisions between protons and C-60 molecules. The collision energy is varied between 1 and 300 keV and we thus cover a velocity range from 0.2 to 3.5 atomic units. The distributions of intact and fragmented C-60 ions have been measured by means of time-of-flight mass spectrometry using pulsed beams or emitted electrons to clock the collision events. The processes leading to multiple ionization and evaporation of neutral dimers are analyzed as functions of the projectile velocity. In contrast to recent findings for He+-C-60 collisions by Schlatholter et al., our results show that the cross sections for ionization and evaporation first increase with velocity, have maxims at around 1-2 a.u., and decrease again for higher velocities. This velocity dependence closely resembles the one for the electronic stopping power indicating that electronic excitations are the main means of energy transfer to C-60 and that this energy is rapidly distributed among the vibrational degrees of freedom. This conclusion is supported by Monte Carlo calculations of nuclear and electronic energy loss for protons passing through and closely outside the C-60 cage.

The dissociation of molecular ions (N-2)(q+) produced by 4.7 MeV/amu Bi-57+,Bi-25+ and 5.9 MeV/amu Xe-43+,Xe-18+ ion impact on N-2 has been studied using the coincidence technique with a position- and time-sensitive multiparticle detector. The kinetic energy release distributions for all observed ion pairs Nq1+ +Nq2+ are measured. Analysis of the distributions is made with emphasis on the highly charged-molecular ions, q>3. In these cases the most probable total kinetic energy of the two fragments is quite well described by the Coulomb explosion model for point charges, while the measured width of the distributions is much larger than that predicted by this simplified model. We therefore suggest a more elaborate model of Coulomb fragmentation based on a statistical description of the individual potential energy curves of the molecular ion This enables us to describe both the position and the width of the kinetic energy release distributions. We suggest that the main cause of the large width of the distributions for the high q values is the spread of the potential energy curves at the equilibrium internuclear distance; this is mainly due to the dispersion interaction arising from the mutual polarization of the atomic ions.