Klasifikacija meteorita spektroskopijom laserski induciranog sloma medija

master's thesis

• Title (english): Classification of meteorites by laser induced breakdown spectroscopy
• Author: Lovro Gudlin
• Mentor: Vedran Đerek (mentor)
• Committee member: Vedran Đerek (predsjednik povjerenstva)
• Committee member: Mario Basletić (član povjerenstva)
• Committee member: Maja Planinić (član povjerenstva)
• Committee member: Marko Tomislav Cvitaš (član povjerenstva)
• Committee member: Željko Skoko (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Physics); Zagreb
• Defense date and country: 2022-11-23, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics

Abstract

U ovom radu korištena je spektroskopija laserski inducirana plazme (LIBS) za klasifikaciju meteorita. Klasifikacija meteorita koja se radila u ovom radu jest na osnovu kemijskog sastava meteorita. Točnije na osnovu srednjih omjera intenziteta spektralnih linija elemenata u meteoritu. Kako bi uopće mogli koristiti takvu metodu, trebali smo napraviti veliku pretpostavku, da je temperatura plazme, kao i gustoća elektrona, ista za svaku spektralnu liniju istog prijelaza (E_k -> E_i). Uz lokalne parametre, degeneracija gornjeg stanja i vjerojatnost prijelaza, pretpostavka bi vrijedila za svaku pojedinačnu liniju. U tom slučaju imali smo linearnu ovisnost intenziteta spektralne linije sa atomskom koncentracijom elementa, uz karakteristični konstantni član za te uvjete. Zbog toga nam je za usporedbu dva uzorka bitno uvijek gledati intenzitet iste linije, tj. istoga prijelaza, elementa u spektru svakog mjesta mjerenja na meteoritu. Također, kao dodatna usporedba za kvalitetu klasifikacije LIBS-om, korištena je i spektroskopija fluorescencije X zraka (XRF). Atomski omjeri elemenata dobivenih XRF-om su se dodatno provjerili sa literaturnim vrijednostima. Usporedba rezultata pokazala je, kao što je i bilo za očekivati, kako su atomski omjeri dobiveni XRF-om najbliži podacima iz literature. Međutim, ako se LIBS uređaj, sa opisanom metodom omjera intenziteta, koristi kao zasebna tehnika, bez usporedbe sa drugima, može se koristiti kao pomoć pri klasifikaciji meteorita. Gledajući grafički prikaz samo srednjih omjera intenziteta referentnih linija elemenata, mogu se uočiti veze između meteorita u istoj grupi.

Abstract (english)

In this work, laser-induced breakdown spectroscopy (LIBS) was used to classify meteorites. The meteorite classification that was done in this paper is based on the meteorite's chemical composition. More precisely, based on the mean ratios of the intensity of the spectral lines of the elements in the meteorite. In order to be able to use such a method at all, we had to make a big assumption, that the plasma temperature, as well as the electron density, is the same for each spectral line of the same transition (E_k -> E_i). With the local parameters, the degeneracy of the upper state and the transition probability, the assumption would hold for each individual line. In that case, we had a linear dependence of the intensity of the spectral line with the atomic concentration of the element, with a characteristic constant term for these conditions. That is why it is important for us to compare two samples to always look at the intensity of the same line, i.e. the same transition, of the element in the spectrum of each measurement location on the meteorite. Also, X-ray fluorescence spectroscopy (XRF) was used as an additional comparison for the quality of LIBS classification. The atomic ratios of the elements obtained by XRF were additionally checked with literature values. The comparison of the results showed, as was to be expected, that the atomic ratios obtained by XRF are the closest to the data from the literature. However, if the LIBS device, with the described intensity ratio method, is used as a separate technique, without comparison with others, it can be used as an aid in the classification of meteorites. Looking at the graphic representation of only the mean intensity ratios of the reference lines of the elements, one can see the connections between meteorites in the same group.

• Keywords: spektroskopija laserski inducirane plazme; klasifikacija meteorita; omjeri intenziteta; spektroskopija fluorescencije X zraka
• Keywords (english): laser-induced breakdown spectroscopy; classification of meteorites; intensity ratios; X-ray fluorescence spectroscopy
• Language: croatian
• URN:NBN: urn:nbn:hr:217:888152
• Study programme: Title: Physics; specializations in: Education; Course: Education; Study programme type: university; Study level: integrated undergraduate and graduate; Academic / professional title: magistar/magistra edukacije fizike (magistar/magistra edukacije fizike)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2022-12-19 13:33:24