Visokorazlučiva spektroskopija rendgenskoga zračenja na ionskoj mikroprobi

doctoral thesis

• Title (english): High resolution spectroscopy of x-rays emission on ion microprobe
• Author: Iva Božičević Mihalić
• Mentor: Stjepko Fazinić (mentor)
• Committee member: Ivo Batistić (predsjednik povjerenstva)
• Committee member: Maja Buljan (član povjerenstva)
• Committee member: Darko Mekterović (član povjerenstva)
• Committee member: Stjepko Fazinić (član povjerenstva)
• Committee member: Damir Bosnar (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Physics); Zagreb
• Defense date and country: 2015-07-13, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics
• Universal decimal classification (UDC): 53 - Physics

Abstract

Na temelju dosadašnjeg iskustva u mjerenjima Kβ spektara 3d prijelaznih metala i njihovih spojeva na već postojećem visokorazlučivom spektrometru rendgenskoga zračenja Laboratorija za interakciju ionskih snopova konstruiran je umanjeni valno disperzivni sustav za rad s fokusiranim ionskim snopovima. Jedna od značajnijih prednosti novog spektrometra je njegova jednostavnost jer su meta i detektor na fiksnim položajima dok se promjena kuta difrakcije postiže linearnim pomakom ravnog kristala duţ osi paralalelne ionskom snopu. Kombinacija ionskog mikrosnopa te CCD detektora dobre prostorne rezolucije omogućila je smanjene dimenzija u odnosu na prijašnje valno disperzivne sustave, čime se je povećala efikasnost sustava, a uz zadržavanje energijskog razlučivanja pogodnog za mjerenja fine strukture rendgenskoga zračenja na mikrometarskim uzorcima. U radu su opisane sve faze izrade spektrometra koje su uključivale optimizaciju geometrije sustava pomoću XTRACE programa te dizajn vakuumske komore u kojoj su smješteni nosač za mete, ravni kristal i detektor. Napravljena je procedura za obradu signala koja dvodimenzionalne slike snimljenog zračenja preoblikuje u visokorazlučive spektre. Novim spektrometrom se proučavao utjecaj kemijskih efekata na karakteristično rendgensko Kα i Kβ zračenje silicija, sumpora i njihovih spojeva pobudom protonima. Utjecaj višestruke ionizacije na finu strukturu karakterističnoga rendgenskoga zračenja je proučavan pobudom ionima ugljika. Ispitane su i mogućnosti spektrometra u razlikovanju spojeva sulfata od sulfida bazirane na kemijskim efektima u Kβ spektrima sumpora te mogućnosti razdvajanja K i M linija rendgenskoga zračenja koje nije moguće razlučiti energijsko disperzivnim detektorima.

Abstract (english)

Downsized high resolution wavelength dispersive x-ray spectrometer was constructed for work with focused beams on ion microprobe. The experience gained in using the present large spectrometer designed for broad beams to measure Kβ spectra of 3d transition metals' and their compounds in the Laboratory for ion beam interactions was taken in account. Important advantage of the new spectrometer is in its simplicity: both target and the detector are mounted on fixed positions while the change of diffraction angle is achieved by linear displacement of the flat diffraction crystal along the axis parallel to the ion beam direction. Downsizing was achieved by combining ion microbeam and CCD detector of good spatial resolution, which together with reasonably good energy resolution enables measurement of the fine structure in x-ray spectra on microscopic samples. All steps of the spectrometer’s development are described and they include geometry optimisation with XTRACE simulations and design of the vacuum chamber which encloses sample holder, crystal and detector. Algorithms for transferring two-dimensional images of the radiation collected with the position sensitive detector to x-ray energy spectra is developed. Spectrometer was used to test influence of chemical effects on characteristic Kα and Kβ x-ray emission of silicon, sulphur and their compounds induced by protons. Multiple ionization and its consequences on characteristic x-ray emission of sulphur were measured with carbon ions. Spectrometer's capabilities to distinguish sulphate and sulphide compounds based on chemical effects in sulphur Kβ spectra induced with protons are demonstrated. Also possibilities to resolve K and M lines that overlap in energy dispersive spectra are shown.

• Keywords: visokorazlučiva PIXE spektroskopija; valno disperzivni spektrometar; ionska mikroproba; kemijski efekti; teški ioni; sumpor; silicij
• Keywords (english): high resolution PIXE spectroscopy; wavelength dispersive spectrometer; ion microprobe; chemical effects; heavy ions; sulphur; silicon
• Language: croatian
• URN:NBN: urn:nbn:hr:217:033388
• 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: 117 str.
• File origin: Born digital
• Access conditions: Open access
• Created on: 2017-08-25 08:15:45