Seeking the Good Fitting Procedure of PALS Polymer Spectra

2008 ◽  
Vol 607 ◽  
pp. 64-66
Author(s):  
Nicolas Laforest ◽  
Jérémie De Baerdemaeker ◽  
Corine Bas ◽  
Charles Dauwe
Keyword(s):  
Experimental Data ◽  
Low Temperature ◽  
Positron Annihilation ◽  
Physical Meaning ◽  
Lifetime Measurements ◽  
Positron Annihilation Lifetime ◽  
Fitting Procedure ◽  
Fitting Procedures ◽  
Blob Model

Positron annihilation lifetime measurements on polymethylmethacrylate (PMMA) at low temperature were performed. Different discrete fitting procedures have been used to analyze the experimental data. It shows that the extracted parameters depend strongly on the fitting procedure. The physical meaning of the results is discussed. The blob model seems to give the best annihilation parameters.

Positron Annihilation Lifetime Measurements in Collagen Biopolymer

1998 ◽  
Vol 530 ◽  
Author(s):  
S. Siles ◽  
G. Moya ◽  
X.H. Li ◽  
J. Kansy ◽  
P. Moser
Keyword(s):  
Positron Annihilation ◽  
Amorphous Region ◽  
Positron Annihilation Spectroscopy ◽  
Lifetime Data ◽  
Spectroscopy Technique ◽  
Lifetime Measurements ◽  
Lifetime Distributions ◽  
Positron Annihilation Lifetime ◽  
Coincidence System ◽  
Three Components

AbstractLifetime measurement in Positron Annihilation Spectroscopy (PAS) is applied to the study of free-volume collagen characteristics as a function of concentration. The lifetimes of positrons were obtained by a conventional fast-fast coincidence system. All lifetime data are fitted in three components by using the computer program POSITRON FIT and resolved. For each concentration, lifetime distributions were analyzed in order to obtain the different components, thus we have observed three components of which a long component τ3. This long lived component can be associated with a pick-off annihilation of ortho-positronium (o-Ps) trapped in free volumes of amorphous region. This investigation shows the potential of the positron annihilation spectroscopy technique in the study of biopolymer microstructures.

On the Limits of Sensitivity of PALS to Incorporated Free Volume Holes in Polymeric Membranes and Sorbents: Effect of sc-CO2 in Polyhexafluoropropylene

2017 ◽  
Vol 373 ◽  
pp. 261-264 ◽  
Author(s):  
Victor Shantarovich ◽  
Valentin Bekeshev ◽  
Nikolai Belov ◽  
Irina Kevdina ◽  
Mikhail Filimonov ◽  
...  
Keyword(s):  
Low Temperature ◽  
Size Distribution ◽  
Positron Annihilation ◽  
Free Volume ◽  
Polymeric Membranes ◽  
Positron Annihilation Lifetime Spectroscopy ◽  
Membrane Materials ◽  
Positron Annihilation Lifetime

Positron annihilation lifetime spectroscopy (PALS) is a recognized instrument for the studies of size-distribution of nanopores (intrinsic free volume holes FVH) in polymers, particularly membrane materials. The limits of this application in the case of “alien” pores, produced by swelling of poly (hexafluoro propylene) PHFP in the gas (CO2) in super-critical (sc-) state are discussed. The obtained conclusions are controlled by measurements of low temperature gas (N2) sorption (LTGS) and by comparison of the data with the results on permeation of various gases through the PHFP membrane. Attention is payed to relaxation with time of the newly created FVH in the PHFP membrane.

Positron annihilation lifetime measurements of mechanically fatigued polystyrene samples

2008 ◽  
Vol 46 (18) ◽  
pp. 1991-1995 ◽  
Author(s):  
J. Erichsen ◽  
C. Nagel ◽  
K. Günther-Schade ◽  
M. Renner ◽  
V. Altstädt ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Lifetime Measurements ◽  
Positron Annihilation Lifetime

scholarly journals POSITRON LIFETIME MEASUREMENTS IN NATURAL RUBBER WITH DIFFERENT FILLERS

2013 ◽  
Vol 22 ◽  
pp. 112-117 ◽  
Author(s):  
A. MANDAL ◽  
S. MUKHERJEE ◽  
S. PAN ◽  
A. SENGUPTA
Keyword(s):  
Natural Rubber ◽  
Positron Annihilation ◽  
Free Volume ◽  
Positron Lifetime ◽  
Amorphous Region ◽  
Filler Concentration ◽  
Lifetime Measurements ◽  
Positron Annihilation Lifetime

Positron annihilation lifetime spectra (PLAS) have been measured for natural rubber polymer with different fillers (Titenium dioxide, Nanosilica and Nanoclay) as a function of filler concentration to investigate how these fillers affect the microstructure of free volume of natural rubber. The lifetime spectra is analyzed by using LT9.0 and the longest lived component(τo-Ps) is attributed to the pick- off annihilation of o-Ps in free volume sites, available mostly in the amorphous region of polymer. On the basis of the τo-Ps values the radii of the free volume holes (Rh) are calculated. The PALS results show that o-Ps lifetime as well as the size of free volume decreases with the increase of filler concentration.

Defects in neutron transmutation doped silicon studied by positron annihilation lifetime measurements

2000 ◽  
Vol 87 (8) ◽  
pp. 3674-3677 ◽  
Author(s):  
M. Coeck ◽  
N. Balcaen ◽  
T. Van Hoecke ◽  
B. Van Waeyenberge ◽  
D. Segers ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Lifetime Measurements ◽  
Positron Annihilation Lifetime ◽  
Doped Silicon ◽  
Neutron Transmutation
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