Spektroskopija elastično izbijenih iona mjerenjem vremena proleta

doctoral thesis

• Title (english): Time of flight elastic recoil detection analysis (TOF-ERDA)
• Author: Zdravko Siketić
• Mentor: Ivančica Bogdanović Radović (mentor)
• Committee member: Damir Bosnar (predsjednik povjerenstva)
• Committee member: Nils Paar (član povjerenstva)
• Committee member: Ivančica Bogdanović Radović (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Physics); Zagreb
• Defense date and country: 2010-05-25, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics
• Universal decimal classification (UDC): 53 - Physics

Abstract

Spektroskopija elastično izbijenih iona mjerenjem vremena proleta (engl. Time-of-flight Elastic Recoil Detection Analysis, TOF-ERDA) je metoda koja se bazira na ozračavanju uzorka snopom teških iona (Cl, I, Au..), energija 1 MeV/A, te istovremenoj detekciji vremena proleta i energije iona izbijenih iz mete. Vremenski/energijski spektar pojedine vrste izbijenih atoma pretvara se u dubinski profil korištenjem poznatog gubitka energije po jedinici puta u materijalu. Mjerenjem vremena proleta različiti atomi osim po energiji odvajaju se i po masi pa se tako mogu dobiti dubinski profili svih elemenata u samo jednom mjerenju. Zbog velike zaustavne moći kako ulaznih tako i izbijenih iona ova metoda ima razlučivost od svega nekoliko nm pri samoj površini. Osim izrade samog TOF-ERDA spektrometra u ovom radu napravljene su i bitne promjene spektrometra koje će omogućiti osjetljivo dubinsko profiliranje i najlakših elemenata (vodika i njegovih izotopa). Dobiveno je poboljšanje efikasnosti za faktor 4 u odnosu na dosadašnje postojeće sustave. Također, radi postizanja dubinske rezolucije od samo 1 nm napravljen je pozicijski osjetljiv detektor za kinematičku korekciju raspršenja. Korištenjem pozicijsko osjetljivog detektora, dobiveno je poboljšanje dubinske razlučivosti pri površini za ~ 20%. Još veća poboljšanja dubinske razlučivosti mogu se očekivati za veće prostorne kuteve.

Abstract (english)

Time-of-flight Elastic Recoil Detection Analysis (TOF-ERDA) is a spectroscopic method developed for measuring depth profiles and concentrations of elements in the unknown sample. Heavy ions (like Cl, I, Au..) with energies of 1 MeV/A are used for recoiling atoms from the target. Energy and time of flight of the recoiled atoms are measured in coincidence which enables us to separate all elements by energy and mass. Time/energy spectra are converted to depth profiles using known relation of energy loss by unit of length of the ions in the sample (stopping power). In comparison to conventional ERDA with a stopping foil in TOF-ERDA all elements can be separated and analyzed in a single measurement. Because of the high stopping power of the heavy ions depth resolution of few nm at the surface can be achieved for C, N and O. TOF-ERDA spectrometer is constructed and modification of foils is performed in order to make it suitable for light element analysis (hydrogen isotopes). Expected enhancement in light element detection by factor of 4 is achieved. Also, in order to perform kinematic correction and improve surface depth resolution (up to 1 nm), a position sensitive detector is constructed and installed at the TOF-ERDA spectrometer. Such kinematic correction improves surface time/depth resolution by ~20%. However, much higher improvements could be expected for larger solid angles of TOF system due to the fact that the kinematic broadening in that case is dominant contribution to the surface time resolution.

• Keywords: elastično izbijanje iona; TOP-ERDA; intrinzična vremenska razlučivost; dubinska razlučivost; masena razlučivost; relativna efikasnost detekcije; LiF; detekcija vodika; SIMNRA; FINLANDIA; CORTEO; mikrokanalni detektor; pozicijski osjetljiv detektor; kinematička popravka
• Keywords (english): elastic recoil; TOF-ERDA; Intrinsic time resolution; depth resolution; mass resolution; relative detection; efficiency; LiF; detection of hydrogen; SIMNRA; FINLANDIA; CORTEO; microchannel plate detector; position sensitive detector; kinematic correction
• Language: croatian
• URN:NBN: urn:nbn:hr:217:416506
• 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: 104 str.
• File origin: Born digital
• Access conditions: Open access
• Created on: 2017-08-24 08:46:09