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Positron Annihilation Lifetime Spectroscopy (PALS) Principles and applications for nano science Principles and applications for nano science Lecture 3 Part 1 Slide 2 Positron Annihilation Lifetime Spectrometer (PALS) Slide 3 POSITRON SOURCES POSITRON-MATTER INTERACTION POSITRON ANNIHILATION LIFETIME SPECTROMETER (PALS) PALS APPLICATIONS on POLYMERS Slide 4 POSITRON SOURCE 1.The decay of neutron-deficiency radio isotopes ( + ), 22 Na 2.Pair formation by high energy - rays Slide 5 22 Na 22 Ne + + + + e Fig. 1 Decay scheme of a 22 Na nucleus Slide 6 POSITRON-MATTER INTERACTION Slide 7 Source preparation and sandwich type sample prepapation Slide 8 POSITRON ANNIHILATION IN MATTER Slide 9 Defect TypeSizeMaterials Atomic Vacancies 0.1 nmMetals Dislocations 1 nm - 10 m Metals Voids 0.1 nm - 1 m Metals Holes 0.1 nm - 10 m Polymers Slide 10 HV; High Voltage power supply, SC; Plastic scintillator, PMT Base; Photomultiplier main base, PMT; Photomultiplier tube, CFD; Constant fraction discriminator, FC; Fast coincidence, DB; Delay box, TAC; Time to amplitude converter, ADC/MCA; Analogical to digital converter/Multi cannel analyzer, 22Na; Positron source within the sample. Fig. 3 Flowchart for PAL spectrometer Slide 11 Slide 12 Slide 13 Slide 14 Energy window for stop Detector (0.51 MeV) Energy window for start Detector (1.28 MeV) Fig. 8 Energy spectrum of 22 Na detected by a multichannel analyzer of PAL spectrometer with the plastic detectors scintillator Slide 15 Fig. 9 Energy spectrum of 22Na detected by a multichannel analyzer of PAL spectrometer, after lower and upper level adjustment for start signals Slide 16 2ns5ns10ns8ns14ns FWHM Fig.10 The prompt curve for 60 Co -rays, under 22 Na window settings at the different delay times (2, 5, 8,10 and 14 ns) Slide 17 Fig.11 The plot of delay time versus channel number The resolution of the instrument =ns/channel x FWHM Resolution of PALS spectrometers are in the range of 190-250 ps Slide 18 PAL spectra of polymers Fig. 13 Positron lifetime spectra of non-irradiated-PE-foam; (a) Count versus channel number (b) Count versus time. One channel corresponds to 0.052 ns. Slide 19 Lifetime distribution of silicon sample 1 = 120 ps, 2 = 320 ps, and 3 = 520 ps. (Math. lab.program, melt) Slide 20 Table 1 Positron annihilation lifetime data of the PE f samples Dose (kGy) 1 (ns)I 1 (%) 2 (ns)I 2 (%) 3 (ns)I 3 (%) 00.360.0178.00.11.050.05100.13.100.1012.00.2 10.360.0182.00.11.030.037.40.12.900.1010.60.2 520.360.0181.00.11.100.107.80.23.000.2011.00.2 980.350.0179.00.10.980.058.80.13.000.2012.00.1 Slide 21 The o-Ps lifetime, o-Ps directly correlates with the radius of free volume holes and its intensity (I o-Ps ) contains information about the free volume concentration (Jean, 1990). The average radius (R) of free volume holes on a quantum mechanical model developed by Tao (1972) and Eldrup et al. (1981) were proposed as follows: R is the average radius of the free volume holes. Ro is a constant = = (1.66 Ro-R Slide 22 Table 2 Radius of a free volumes and volumes of PE-Foam polymers as a function of the dose Dose (kGy) Radius (), ( 3 ) Volume ( 3 ),( 3 ) Radius (), ( 2 ) Volume ( 3 ), ( 2 ) 03.702121.7422.1 13.571901.7121.0 523.642021.8225.2 983.642021.6318.1 Slide 23 The correlation between free volume and gas separation properties in high molecular weight poly(methyl methacrylate) membranes, Ywu-Jang Fu et al. European Polymer Journal 43 (2007) 959967 Slide 24 Slide 25 Dichloromethane Buthylacetate Slide 26 The correlation between free volume and gas separation properties in high molecular weight poly(methyl methacrylate) membranes, Ywu-Jang Fu et al. European Polymer Journal 43 (2007) 959967 26 Butil asetat 996000 Slide 27 Positron annihilation lifetime spectroscopy of molecularly imprinted hydroxyethyl methacrylate based polymers Nikolay Djourelov, Zeliha Ates, Olgun Gven, Marijka Misheva, Takenori Suzuki Polymer 48 (2007) 2692-2699 Free-volume hole radius (R)) for dry samples versus the type of crosslinking agent at different concentrations. Irradiated samples (D = 5 kGy) with 3:1 HEMA:glucose mole ratio; symbols : , , , and indicate 70, 30, 20, 10% and no crosslinking agent containing samples, respectively. NA indicates sample prepared without crosslinking agent. 27 Slide 28 Slide 29 Slide 30 Slide 31 Study on the microstructure and mechanical properties for epoxy resin/montmorillonite nanocomposites by positron B. Wang and et al. Radiation Physics and Chemistry 76 (2007) 146149 31 Slide 32 Slide 33 Positron Annihilation Lifetime Spectroscopy (PALS) Principles and applications for nano science. Principles and applications for nano science. Lecture 3 Part 2 Slide 34 Spur Terminal Spur (Blob) e + (200 keV) e-e-e-e- e-e-e-e- e + (~ eV) e-e-e-e- e-e-e-e- e-e-e-e- e-e-e-e- e-e-e-e- Thermalization ++++ ++++R R ++++ R ++++ ++++ R ionization and excitation of atoms ionization and excitation of atoms free radicals free radicals molecule dissociation molecule dissociation defects in crystalline structures defects in crystalline structures t ~ 1 ps Slide 35 Hydrogen-like bound state of an electron and a positron.Hydrogen-like bound state of an electron and a positron. Exists in two states: p-Ps( ) and o-Ps( ) (1:3)Exists in two states: p-Ps( ) and o-Ps( ) (1:3) In vacuum: p-Ps lives 0.125 ns, o-Ps 142 ns.In vacuum: p-Ps lives 0.125 ns, o-Ps 142 ns. In Polymers o-Ps lifetime is quenched to some ns because of the pick-off annihilation.In Polymers o-Ps lifetime is quenched to some ns because of the pick-off annihilation. What is Positronium? e + + e - =Ps Slide 36 22 Na Methods of positron annihilation t - PALS e+e+e+e+ 1274 keV 511 keV E 1 +E 2 - CDBS t, E 1 -511 - AMOC - ACAR E 1 -511 - DBAL sample e-e-e-e- Positron Annihilation Lifetime Spectroscopy Angular Correlation of Annihilation Radiation Doppler Broadening of Annihilation Line Coincidence Doppler Broadening Spectroscopy Aged MOmentum Correlation termalization 511 keV diffusion ~ 100 nm Slide 37 Crosslinking in molecularly imprinted polymers poly(2-hydroxyethyl methacrylate) (HEMA) crosslinking agents: diethylene glycol diacrylate (DEGDA) polypropylene glycol dimethacrylate (PPGDMA, Mn=560) triethylene glycol dimethacrylate (TEGDMA) N. Djourelov, Z. Ate, O. Gven, M. Misheva, T. Suzuki, Polymer 48 (2007) 2692-2699 Slide 38 Slide 39 Slide 40 Positron annihilation lifetime study of organic- inorganic hybrid materials prepared by irradiation N.Djourelov, T.Suzuki, M.Misheva, F.M.A.Margaa, I.M.Miranda Salvado, J Non-Crystalline Solids 351 (2005) 340345 PDMS+Silica 1 long-lived component PDMS+Silica+Zirconia 2 long-lived components + SiO 2 (+ZrO 2 ) Slide 41 Slide 42 POZTRON YOK OLMA YAAM SRES SPREKTROMETRESNDE KULLANILAN PROGRAMLAR TL9 MELT PORE SZE CALCULATION ORIGIN /EXCEL Slide 43 LT 9 program kullanlarak elde edilen eriler Slide 44 PALS POSITRONFIT POSITRONFIT PALFIT PALFIT LT v.9 LT v.9 Slide 45 Tao-Eldrup model Goworek-Gidley model Slide 46 Intensity 1dev. Intensity 2dev. Intensity 3dev.Lifetime1dev.Lifetime2dev.Lifetime3dev. 14.97023.04259557.65482.47297127.3751.3531910.1619570.0218910.3579350.0112492.2508710.044658 28.246082.60157847.257612.33954224.496311.163150.200490.0129910.4087040.0124482.3369010.026631 20.442592.96818855.4282.54450724.129411.2224450.1836350.0182460.3804410.0103132.2910970.017953 21.660713.0230854.071862.61232124.267431.2705450.190890.0178170.3799610.0101092.2490730.024455 50.247613.18859627.903653.44435321.848741.4055120.2633480.0096110.4962060.0299462.3661920.017751 25.959494.59990950.847894.07782723.192621.9074170.2100010.0183280.3896690.0173682.2715070.041216 33.720337.36920143.431746.95521722.847933.1907740.2365780.0230910.4054180.0328322.2588720.051926 25.35935.61571252.505024.97078822.135682.2143480.2119580.0225770.3888930.0203362.2838180.045165 Slide 47 Continuous Distribution More realistic presentation: continuous distributionMore realistic presentation: continuous distribution CONTIN CONTIN MELT MELT LT v.9 LT v.9 Slide 48 dev Sorusu : Nano boluklar olan bir malzemenin pozitron yok olma yaam sresi spektrometresi (PALS) ile incelenmesi sonucunda aadaki spektrum elde edilmitir. Bu malzemede bulunan (a) en byk (b) en kk boluun ve (c) saysal olarak en fazla oranda bulunan boluun bykl ka nm dir. NOT : Grafik verilerine ulamak iin buraya tklaynz : PALS dev verileri (verileri sayfay slayt gsterisi ekline dntrdkten sonra alabilirsiniz)PALS dev verileri p-Ps( ) o-Ps( ) Ps