Nanoscale Track Diameter and Hydrogen Yield: Dependence upon Charge State of Incident Ion on Polystyrene

Divya Gupta ,R.s Chauhan ,Ambuj Tripathi ,Santanu Ghosh ,P.k Diwan ,S Kumar ,Shahjahan Khan ,Mittal Vk

doi:10.4236/wjcmp.2013.31016

Abstract

The study of radiation damage of high- molecular weight substances due to MeV ion interactions is of interest for engineering and scientific applications. In the present study polystyrene (PS) was irradiated with 107Ag ions of three different charge states (q) 11+, 14+ and 25+ and of 130 MeV energy. The emission of hydrogen from PS was monitored as a function of the incident ion fluence. The experimental results showed that the hydrogen depletion per incident ion from PS varies as qn, where n was found to be 2.1 as compared to the value 2.7 to 3.0 reported in the literature. Radii of the nanometric damaged zones or ion tracks formed were analyzed from the slope of the hydrogen depletion versus ion fluence curves as a function of charge state of incident ion. These have values between 3.2 - 6.8 nm. These radii were found to depend upon the charge state of the incident ion and vary as qm, where m has the value 0.9.

Highlights

When the charged particles like electrons, heavy ions or radiations like γ rays with sufficient energy (MeV’s energy) pass through a solid, they transfer their energy, mainly through electronic ionization and excitation, of the constituent atoms and molecules [1]
Radii of the nanometric damaged zones or ion tracks formed were analyzed from the slope of the hydrogen depletion versus ion fluence curves as a function of charge state of incident ion
This behavior is in accordance with the results reported earlier by Schiwietz and Grande [17,18] that the electronic stopping power depends upon the charge state of the incident ion

Summary

Introduction

When the charged particles like electrons, heavy ions or radiations like γ rays with sufficient energy (MeV’s energy) pass through a solid, they transfer their energy, mainly through electronic ionization and excitation, of the constituent atoms and molecules [1]. As a result, localized regions of extensive chemical and structural transformations due to radiation damage are formed along the ion paths. This causes creation of a so called ion track (a nanometric size cylindrical amorphized zone) [3,5,6] corresponding to each incident ion. Steckenreiter et al [3] studied the MeV Kr and Mo ion induced modifications in polyethylene terephthalate (PET) and deduced the ion track radius by considering the Fourier transform infra red absorbance measurements. Partial pressure studies of various gasses emitted from 180 MeV Ag ion irradiated PET using quadrapole mass analyzer revealed the ion track radii with good accuracy [6]

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