Projects / Programmes
Studies of atoms, molecules and structures with photons and particles
January 1, 2009
- December 31, 2014
| Code |
Science |
Field |
Subfield |
| 1.02.00 |
Natural sciences and mathematics |
Physics |
|
| Code |
Science |
Field |
| P230 |
Natural sciences and mathematics |
Atomic and molecular physics |
| Code |
Science |
Field |
| 1.03 |
Natural Sciences |
Physical sciences |
Atomic physics, molecular physics, electron correlations, photoabsorption, fluorescence, Auger spectroscopy, time-of-flight spectroscopy, X-ray spectroscopy, Moessbauer spectroscopy, physics of surfaces, vibrationally excited hydrogen, He atom scattering, ion beam accelerator, ion beam analytical methods, EXAFS, XANES, PIXE, RBS, ERDA, electron scattering, ion microbeam.
Researchers (21)
Organisations (4)
Abstract
Research activity under the program is concentrating on two main aspects accessible by low energy excitation of various targets by photons and particles. The first regards a basic interaction of photons and particles with an atom. Its aim is to observe and explain correlation effects that go beyond the first order approximation where the atom is represented by a system of independent electrons moving in the average, local and static potential. We propose to study multielectron excitations of inner atomic shells by photon absorption and high resolution X-ray spectroscopy, providing information of both, the excitation distribution of the atom and branching of the relaxation decay paths. To test thoroughly the model predictions we are going to measure multidifferential scattering cross sections, for example, Auger electron - ion coincidence pairs after the electron beam excitation of the gas target. The research is devoted also to the study of vibrationaly excited hydrogen molecules, specifically to their interaction with the surface of materials which are relevant for the fusion research. The second main aspect of our research activity is to perform experiments under conditions of firm validity of the first basic approximations in order to study the structure in which the atoms are immersed. The atomic signal is often strongly modulated by the atom environment even in materials with medium and short-range order. We are going to study the structure by exciting the target with synchrotron radiation recording the X-ray and photoelectron diffraction patterns or by measuring the extended fine structure in the absorption cross section (EXAFS). The structure will be also studied by measuring the inner hyperfine magnetic and electric field of thin layers by means of Moessbauer spectroscopy and by observing the chemical shifts in the HRXRS. The surfaces in particular will be studied by scattering of the thermal beam of helium atoms. The ion beam excitation is going to be used for determination of elemental concentrations in various multilayered materials and samples by different ion beam techniques (RBS, PIXE, ERDA). Such nondestructive analysis will be performed, for example on the works of art, on the aerosol samples, in the geology and arheometry. Two-dimensional maps of elements can be measured with the ion beam microprobe reaching 1 um of lateral resolution. A particular attention will be devoted to the study of new materials like thin organic films on semiconductor or metal substrates and nanostructures. With more reliable data about the structure the golden dream of the material science is becoming true: the possibility of theoretical construction of new materials with the desired properties.
Significance for science
The scientific importance (relevance) of the programme research results is twofold: direct and indirect. In the first case we deal with explicit studies of atomic and molecular behavior in the presence of intense and coherent EUV light (resonant multiphoton absorption, superfluorescence) and with the observations and characterization of weak (rare) transitions which reveal correlation mechanisms that are of interest for a few body physics of Coulomb systems (multielectron transitions, fragment rearrangement in molecular dissociation). The second case is based on adjustment, combination and introduction of new experimental techniques that offer a fresh or a completely new look on a specific problem in the field of material analysis. The data set obtained that way, especially if taken in the in-situ or in-operando mode, can be of fundamental importance for people synthesizing or using the material. With bright synchrotron light sources we have recently obtained excellent results with our high resolution X-ray spectrometer. The emerging results are important for development of the science since they enable an insight into the fundamental physical phenomena (separation of doubly excited states, nonlinear Raman and interference effects, Radiative Raman effect) with so far the sharpest spectroscopic images. Another advantage is wide selection of synchrotron and ion-beam techniques that have found an expertise in our research programme. This allows for the ''total'' study of a certain problematics as shown, for example by our research on chlorohydrocarbon's response to creation of an inner core hole: for a group of compounds we have measured the chlorine K-shell photoabsorption and RIXS signal (ESRF) and the HAXPES signal (SOLEIL). We have also measured L-VV Auger spectra, the total ion yield and the mass spectra upon L-shell formation as a function of excitation energy (MAXLAB2) and also ionic fragments in coincidence with the Auger electrons (MAXLAB) well as mass spectrometry. For these molecules we plan to investigate the formation of a double KL core by the magnetic bottle spectrometer (SOLEIL). Systematic measurements of charge transfer (CT) dynamics in different molecule/substrate systems, are expected to identify relevant molecule-substrate coupling parameters such as adsorption geometry (angle, distance), adsorption energy, energy level alignment, from the substrate transport characteristics which determine the rate and direction of electron transfer through the hybrid interfaces. In addition to studying static CT to acceptor molecules via hybridization and charge dipole formation at the hybrid interfaces, the expected results on dynamic backtransfer will provide additional insight on molecular capabilities to transport electrons over empty molecular orbitals. The possibility to exploit CHC method for ultrafast charge backtransport to acceptor molecules promises to become a powerful tool in studying electronic structure at hybrid interfaces. The obtained results will allow a better understanding of fundamental electronic properties of molecular nanoassemblies that will lead to a better, knowledge based design of novel organic based components for organic electronics. X-ray absorption spectroscopy (XAS) with EXAFS and XANES techniques is indispensable tool for development of new functional (nano) materials with desired properties. An example is in-operando characterization of atomic structure and electrochemical processes in cathode materials of Li-ion or Li-sulphur battery during charging and discharging. Obtained results are crucial for development of new cathode materials with higher energy density and long term stability. Similar goals are followed in the ‘’in-situ'' EXAFS and XANES research of catalytic properties of different micro and mesoporous catalysts and zeolites, where crucial structural and chemical parameters of incorporated metal cations (site of incorporation, valence state, local structure) are monitored.
Significance for the country
Our expertise with x-rays (EXAFS, XANES, RIXS, potentially XRS) and ion beam methods (PIXE, RBS, ERDA, NRA, PIGE and SIMS) together with their micro- versions allows Slovenian and foreign laboratories working in the field of material research, geology, chemical synthesis, pharmacology, biology, vacuum technology, environmental research, cultural heritage preservation, etc, to approach modern analytical methods with synchrotron light and ion beams. Our application-oriented measurements were and will be performed at synchrotron research centers like ELETTRA, ESRF, DESY and at the ion beam facility Mikroanalitical Center JSI where mostly our own instrumentation is being used. We participated in the development of several technologically important materials, such as batteries, microporous catalysts, superconducting and ferroelectric ceramics, surfactants, thin layer and self-cleaning coatings and some pharmaceutical molecules, and we helped in a development of a digital processing electronics. We are active in solving the environmental problems due to pollution with heavy metals, pesticides and biological agents, and in preservation of the cultural heritage. Our intensive presence at European synchrotron centers and successful visits of researchers from abroad at MIC IJS are strengthening the international scientific collaboration. In 2009-2014 period we have performed with collaborators altogether 81 officially assigned synchrotron projects and have hosted 23 TNA (Trans-National-Access) projects at ion accelerator centre MIC JSI. Our presence in the international research centers, at international workshops and conferences allows for a research work of an enduring quality, the access to the foreign knowledge and indirectly, a generation of a positive image of Slovenia. The experimental research group from one lab collaborates with a group of theoreticians from the other institute, or, material synthesized by one group is characterized by several other groups using different techniques: such an international division of work is constantly met at our work. Besides direct teaching duties that our researchers are executing at different faculties, from pedagogical point of view also a regular access to the synchrotron and ion accelerator beamlines is important to demonstrate to students a wealth of existing experimental approaches. These techniques are also presented in a number of academic programs at the undergraduate or graduate level. The students can gain knowledge about modern analytical techniques with synchrotron light and ion beams by direct involvement in our experiments or/and by participation in the data analysis. The program equally provides an opportunity for Slovene scientists to gain experience in the surface and material sciences and transfer the high-technology know-how to the research and industrial labs. The development of ferroelectric thin layers, catalysts, new battery materials, and self-cleaning coatings are just a few examples of economically interesting, market-oriented applications. In a particularly fruitful, long term collaboration with Institute of Chemistry and CO NOT new nanostructured cathode materials for Li-sulphur batteries have been developed. Li-S batteries (EUROLIS – FP7 EU project) are most promising for electric cars, since they are expected to provide the car autonomy of 500 km. The XAS analysis of valence and atomic neighborhood of sulphur during battery operation shed light into the electrochemical dynamics and helped to optimize the capacity. Our involvement with setting up a fusion reactor and in the free-electron-laser related research allows, in principle, the contact with the most advanced technologies, which, in the next phase, will be commercialized offering an opportunity for the spin-off activities. We are actively collaborating in finding the solutions for the environment reconstruction due to the heavy metal and dust pollution.
Most important scientific results
Annual report
2009,
2010,
2011,
2012,
2013,
final report,
complete report on dLib.si
Most important socioeconomically and culturally relevant results
Annual report
2009,
2010,
2011,
2012,
2013,
final report,
complete report on dLib.si
