An experimental test on the distribution of positronium lifetimes in polymers

Consolati, G.; Rurali, Riccardo; Stefanetti, Mariangela

doi:10.1016/s0301-0104(98)00249-3

Cited by 17 publications

(19 citation statements)

References 25 publications

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“…Such a comparison enables to check some ideas on the mechanisms of o-Ps trapping and the accuracy of the lifetime spectrums processing. [33][34][35][36][37] For the super-crosslinked polystyrene 36 (Table2), there was found a good correlation between PAL and sorption data, when longlived o-Ps components s 4 , I 4 and s 5 , I 5 were used. A good correlation was seen in the fact that, from the pores detected by sorption method, o-Ps was always trapped by those having smaller size but higher concentration.…”

Section: Pal Results For Ptmsp Pim-1 and Af2400mentioning

confidence: 87%

“…For the case of PTMSP, attempts were done 33 either to introduce a dispersion of the fourth component (3D,1G, r 4 ¼ 3.4 ns) (see eq 4) or to use additional discrete o-Ps component (the case 5D). We have to stress that a comparison of the two cases may be productive only at extremely high statistic of measurements (integral number of counts in one curve 33 was as high as 6 Â 10 7…”

Section: Pal Results For Ptmsp Pim-1 and Af2400mentioning

confidence: 99%

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Positron annihilation and free volume studies in polymer glasses

Shantarovich

2008

J Polym Sci B Polym Phys

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Section: Pal Results For Ptmsp Pim-1 and Af2400mentioning

confidence: 87%

Section: Pal Results For Ptmsp Pim-1 and Af2400mentioning

confidence: 99%

Positron annihilation and free volume studies in polymer glasses

Shantarovich

2008

J Polym Sci B Polym Phys

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“…Implemented in LT programme the DMF model works fine if only one dispersed component is present, giving additional information about width of the distribution. There is also a possibility to evaluate component's lifetime distribution substituting it by a sum of two exponential components [6][7][8].…”

Section: Methods Of Numerical Analysismentioning

confidence: 99%

“…The results were shown in the same figures in comparison. However, it is known that MELT has a tendency to split a wide distribution of lifetimes into two narrower ones for polymers [6,9]. In order to test this effect in the range of long lifetimes the spectrum was simulated assuming a wide lognormal dispersion of lifetimes.…”

Section: Remarks On Meltmentioning

confidence: 99%

Measurement and Analysis of the Positron Annihilation Lifetime Spectra for Mesoporous Silica

Zaleski

2006

Acta Phys. Pol. A

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Positron annihilation lifetime spectroscopy as a technique of porous materials investigation is still under development. Both measurement conditions and lifetime spectra analysis methods have to be adapted to the requirements of positron porosimetry. If complex positron annihilation lifetime spectra of porous materials are processed, numerical methods of lifetime spectra analysis have to be used with a particular care. Among various methods of positron annihilation lifetime spectra analysis available, the most popular ones were tested implemented in programs MELT and LT. It was found, from the simulated spectra study, that a large number of counts in a spectrum is needed to obtain reliable results of analysis. Even then only an approximate solution is available. Determination of the approximation nature helps in a further interpretation of the results and in positron annihilation lifetime spectrometer setting adequate to the problem. For this purpose, a few complex spectra obtained from positron beam facility were tested. The results show a negligible influence of resolution function on long lifetime components, while the precise estimation of the background level is crucial. Also some distortions caused by imperfection of numerical analysis methods are pointed out.

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“…On the other hand, analysis in terms of a distribution of o-Ps lifetimes allows one to get the volume distribution function of the nanoholes [2]. In a recent paper [3] we showed the superiority of the latter model with respect to that one where each positron state decays with a single time constant; in the present work we compare the results supplied by two algorithms able to give lifetime distributions, that is, MELT [4] and LT [5]. .…”

Section: Introductionmentioning

confidence: 91%

Discrete and Continuous Analysis of Positron Lifetime Spectra: a Comparison

Consolati

Quasso

1999

Acta Phys. Pol. A

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Positron lifetime spectra in poly [1-(trimethylsilyl)]propine membranes were collected at different temperatures and various number of accumulated counts, in order to compare the results from analyses obtained by different decay models: discrete (that is, purely exponential) or continuous (with at least one distribution of lifetimes). Analysis into four discrete components is inadequate, unless a low number of counts (1 to 2 millions) is accumulated. Conversely, deconvolutions which allow the ortho-positronium lifetime to be distributed give satisfactory fits, even at the highest statistics (60 millions). An equivalent good fit in terms of x 2 test is obtained with a five discrete components analysis, from which it is possible to extract information on the first moments (centroid and standard deviation) of ortho-positronium lifetime distribution.

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An experimental test on the distribution of positronium lifetimes in polymers

Cited by 17 publications

References 25 publications

Positron annihilation and free volume studies in polymer glasses

Positron annihilation and free volume studies in polymer glasses

Measurement and Analysis of the Positron Annihilation Lifetime Spectra for Mesoporous Silica

Discrete and Continuous Analysis of Positron Lifetime Spectra: a Comparison

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