Kemijski učinci u Kbeta spektrima rentgenskog zračenja pobuđenog protonskim snopom u 3d elementima i njihovim spojevima

doctoral thesis

• Title (english): Chemical effects in K spectra of X-ray emission induced by proton bombardment of 3d elements and their compounds
• Author: Luka Mandić
• Mentor: Stjepko Fazinić (mentor)
• Committee member: Damir Bosnar (predsjednik povjerenstva)
• Committee member: Hrvoje Buljan (član povjerenstva)
• Committee member: Stjepko Fazinić (član povjerenstva)
• Committee member: Ksenofont Ilakovac (član povjerenstva)
• Committee member: Damir Veža (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Physics); Zagreb
• Defense date and country: 2011-05-25, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics
• Universal decimal classification (UDC): 53 - Physics

Abstract

Visokorazlučiva spektroskopija rentgenskog zračenja induciranog protonima (PIXE) energije 2 i 3 MeV primjenjena je za kemijsku karakterizaciju izabranih 3d elemenata (Ti, V, Cr) u različitim spojevima. U izmjerenim Kβ spektrima uočeni su kemijski učinci i identificirani su njihovi kvantitativni pokazatelji: relativne energije i intenziteti linija Kβ2,5 i Kβ′′ koje posjeduju molekulski karakter. Mjerenje i modeliranje spektara izvedeno je sistematskim pristupom, kako bi se prevazišle diskrepancije u postojećim publiciranim podacima, temeljenim na različitim tehnikama (pobude ionima i fotonima) i spektralnim modelima. Predložen je novi model za određivanje utjecaja apsorpcije pobuđenog rentgenskog zračenja unutar same mete. Model uzima u obzir finu strukturu apsorpcijskog koeficijenta oko K−ruba, izvedenu iz XANES spektara istih spojeva. Prikupljena baza spektralnih parametara ovisnih o strukturi kemijskog okoliša pokazuje da je ovom metodom moguća: (i) identifikacija ligand atoma s kojim se vežu 3d elementi, (ii) određivanje oksidacijskog stanja 3d elementa u spoju, te (iii) određivanje srednje duljine veze između 3d atoma metala i atoma liganda u spoju.

Abstract (english)

High resolution spectroscopy of x-ray emission induced by 2 and 3 MeV protons (PIXE) was used for chemical characterization of selected 3d elements (Ti, V, Cr) in various compounds. In the measured Kβ spectra, specific chemical effects were observed and their quantitative indicators were identified: the energy and intensity of Kβ2,5 and Kβ′′ x-ray lines, which posses a molecular character. In order to reveal the background of large discrepancies in the existing experimental data, obtained by different techniques (ion or photon induced x-ray emission) and data analysis procedures, measuring and modelling of presented spectra were performed in a consistent way. A new spectral model and data analysis procedures were developed to resolve the influence of the thick target self-absorption on induced x-ray emission. The developed model takes in account the fine structure of x-ray absorption coefficients near the K−edge. These coefficients were extracted from published XANES data measured for identical compounds. The collected data set of spectral parameters sensitive to chemical environment confirmed that the method could be usefull for: (i) ligand species identification in 3d metal compounds, (ii) determination of oxidation state of 3d metal, and (iii) average metal–ligand bond length determination.

• Keywords: PIXE; WDS; visokorazlučiva spektroskopija rentgenskog zračenja; 3d elementi; Kβ spektar; oksidacijsko stanje; kemijski učinci; kemijski okoliš; ligandno polje; srednja duljina veze; meduatomski prijelaz; apsorpcija u debeloj meti
• Keywords (english): PIXE; WDS; high-resolution x-ray spectroscopy; 3d elements; Kβ spectrum; oxidation state; chemical effects; ligand field; average bond length; inter-atomic transition; absorption in thick target
• Language: croatian
• URN:NBN: urn:nbn:hr:217:368966
• Study programme: Title: Physics; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor/doktorica znanosti, područje prirodnih znanosti, polje fizika (doktor/doktorica znanosti, područje prirodnih znanosti, polje fizika)
• Type of resource: Text
• Extent: 128 str.
• File origin: Born digital
• Access conditions: Open access
• Created on: 2017-08-23 12:28:36