Naslov
Chemical speciation of phosphorus, sulfur and chlorine by means of high-energy resolution PIXE measurements

Autori
Petric, Marko ; Kavčič, Matjaž ; Žitnik, Matjaž ; Bučar, Klemen ; Szlachetko, Jakob

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
IBA2015 Book of Abstracts / Bogdanović Radović, Iva ; Jakšić, Milko ; Karlušić, Marko ; Vidoš, Ana - Opatija : Institut Ruđer Bošković, 2015, 201-201

ISBN
978-953-7941-07-9

Skup
22nd International Conference on Ion Beam Analysis

Mjesto i datum
Opatija, Hrvatska, 14.06.2015. - 19.06.2015

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
high-energy resolution PIXE, density functional theory, phosphorus, sulfur and chlorine

Sažetak
High-resolution x-ray emission spectroscopy (XES) is directly probing the charge density around x-ray emitting atom and can be used complementary to x-ray absorption technique (XAS) to study electronic structure of selected element. Since spectral features, e.g. energy position and spectral shape are independent on the type of excitation, such analysis is not restricted to synchrotron facilities and can be performed also with laboratory excitation sources. In this work, 2 MeV proton beam was used to induce Kα and Kβ emission spectra of several phosphorus, sulfur and chlorine containing compounds including various oxidation states, structures and ligand environments. The high-energy resolution spectrometer in Johansson geometry [1] optimized for tender x-ray energy range was used in the experiment. The energy resolution (~0.5 eV) below the natural linewidth of the measured K lines allows us to study the chemical environment of the element in the sample. The measured energy shifts of the most intense Kα diagram line can be related to oxidation state of the studied element in the target. The characteristic, atomic-like Kα1, 2 spectral shape allow us a precise and robust analysis of oxidation state. Chemical sensitivity is increased further in Kβ emission spectra, which originate from valence-core transition and reflects directly the chemical environment of the elements. Quantum chemical calculations employing the StoBe-deMon molecular/cluster software package, [2] based on density functional theory (DFT) were performed to obtain electron densities around selected atom together with corresponding molecular orbitals and partial charges. Measured Kα energy shifts are reproduced by the calculations, clear correlation between measured energy position and calculated valence shell electron population was obtained. Measured Kβ spectra are well reproduced by the DFT calculations, main spectral components are interpreted in terms of molecular orbitals. Finally, the influence of bonding, ligand type and symmetry on the measured spectra is analyzed.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

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