A modified set-up to reduce background spectra in the CDBS positron spectrometer

Ghasemifard, Mahdi; Ghamari, Misagh

doi:10.1140/epjp/s13360-021-02196-z

Cited by 5 publications

(2 citation statements)

References 21 publications

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“…Therefore, usually the results are presented in a relative form and are measured according to a reference sample. 7 One of the important factors in the analysis of the obtained results is the resolution of detectors. The resolution of the detector has an effect on the broadening of the central part of the spectrum, and since this has a physical meaning, it is not possible to compare two spectra with different detectors.…”

Section: Results Of Cdbsmentioning

confidence: 99%

“…In the method of determining the Doppler broadening, unlike the method of determining the length of life in which the values of the length of life obtained in different laboratories for different materials are different, the difference in the laboratory tools causes a change in the shape of the spectrum. Therefore, usually the results are presented in a relative form and are measured according to a reference sample 7 . One of the important factors in the analysis of the obtained results is the resolution of detectors.…”

Section: Resultsmentioning

confidence: 99%

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Characterization of polar groups in polyvinyl chloride–ethyl vinyl acetate blends using coincidence Doppler broadening spectroscopy

Ghasemifard,

Ghamari

2023

J of Applied Polymer Sci

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Coincidence Doppler broadening spectroscopy (CDBS), known for its exceptional precision, is extensively employed in examining the electronic states of polymers. In this study, polyvinyl chloride (PVC)–ethyl vinyl acetate (EVA) polymers blends were prepared using conventional techniques, following specific ratios (75:25, 50:50, and 25:75, respectively). Spectroscopic analysis reveals that the longitudinal component of linear momentum surpasses the momentum unit (i.e., 10−3 m0c) when considering the ratio curve associated with the participation of oxygen core electrons. When compared to non‐polymer samples, the PVA polymer and PVA–EVA polymer blend exhibit greater free volume voids in contrast to non‐polymer structural defects. Furthermore, the annihilation of ortho‐positronium with core electrons, likely EVA oxygen core electrons, contributes to the measured free volume voids. An increased annihilation of positrons or positroniums by oxygen in the CDBS spectrum leads to higher calculated W parameter values. Conversely, as the PVC content increases, the W parameter decreases, suggesting reduced ortho‐positronium annihilation and consequently, enhanced formation of para‐positronium in the overall annihilation process. In summary, this investigation demonstrates the utility of CDBS in elucidating the electronic states and free volume voids in PVC and EVA polymers.

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Section: Results Of Cdbsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%