In Situ Raman Spectroscopy Monitoring of Material Changes During Proton Irradiation

Abstract

Organic molecules are prime targets in the search for life on other planetary bodies in the Solar System. Understanding their preservation potential and detectability after ionic irradiation, with fluences potentially representing those received for several millions to billions of years at Mars or in interplanetary space, is a crucial goal for astrobiology research. In order to be able to perform in situ characterization of such organic molecules under ionic irradiation in the near future, a feasibility experiment was performed with polymer test samples to validate the optical configuration and the irradiation chamber geometry. We present here a Raman in situ investigation of the evolution of a series of polymers during proton irradiation. To achieve this goal, a new type of Raman optical probe was designed, which documented that proton irradiation (with a final fluence of 3.1014 at·cm–2) leads to an increase in the background level of the signal, potentially explained by the scission of the polymeric chains and by atom displacements creating defects in the materials. To improve the setup further, a micro-Raman probe and a temperature-controlled sample holder are under development to provide higher spectral and spatial resolutions (by reducing the depth of field and laser spot size), to permit Raman mapping as well as to avoid any thermal effects.

Exploring New Methods to Study and Moderate Proton Beam Damage for Multimodal Imaging on a Single Tissue Section

“…Previous work has considered proton beam damage to various sample types across multiple disciplines, for example, proton beam damage to graphene − and polymers. − Extensive research on proton beam damage to cultural heritage objects has also been carried out, but most studies considered only visible damage in paints, parchment, and paintings. − Visible changes, as well as changes to light element concentrations in tissues and cells, have been observed following proton beam irradiation. , The effect of proton beam irradiation to living cells has also been characterized in terms of biological response and DNA damage, due to the relevance to proton beam cancer therapy. , There is, however, a dearth of information on proton beam damage to lipid or other metabolite markers in tissues, which this work seeks to address by considering mechanical damage to lipids.…”