Use of WetSEM\xae capsules for convenient multimodal scanning electron microscopy, energy dispersive X-ray analysis, and micro Raman spectroscopy characterisation of technetium oxides

D J Bailey,J Heo,N C Hyatt,M C Stennett

doi:10.1007/s10967-021-07737-5

Abstract

SEM–EDX and Raman spectroscopy analysis of radioactive compounds is often restricted to dedicated instrumentation, within radiological working areas, to manage the hazard and risk of contamination. Here, we demonstrate application of WetSEM® capsules for containment of technetium powder materials, enabling routine multimodal characterisation with general user instrumentation, outside of a controlled radiological working area. The electron transparent membrane of WetSEM® capsules enables SEM imaging of submicron non-conducting technetium powders and acquisition of Tc Lα X-ray emission, using a low cost desktop SEM–EDX system, as well as acquisition of good quality μ-Raman spectra using a 532 nm laser.

Highlights

Technetium (Tc) is a high-yield fission product of both plutonium and uranium (6% fission yield for 235U)
Scanning electron microscopy (SEM), coupled with energy dispersive X-ray analysis (EDX), is an essential characterisation technique employed in materials science to examine the microstructure, morphology and elemental composition of materials with spatial resolution
The method uses a disposable cold-seal capsule to isolate the hydrated substance, with a thin electron transparent window to allow imaging. We considered that such a capsule could adequately function as a device for containment and multimodal SEM–EDX and μ-Raman analysis of radiological specimens, with moderately high specific activity, such as 99Tc, without the need for dedicated instrumentation

Summary

Introduction

Technetium (Tc) is a high-yield fission product of both plutonium and uranium (6% fission yield for 235U). There is considerable research directed at the synthesis and characterisation of Tc wasteforms and. Tc is a soft (293 keV) beta emitter, with moderately high specific activity (6.2 × 1 08 Bq.g−1) and must be handled in an appropriate radiochemical laboratory to prevent inhalation of particulates and transfer of contamination through volatilisation. Scanning electron microscopy (SEM), coupled with energy dispersive X-ray analysis (EDX), is an essential characterisation technique employed in materials science to examine the microstructure, morphology and elemental composition of materials with spatial resolution. Μ-Raman spectroscopy is a useful characterisation technique for the elucidation of material structure with spatial resolution. Application of these techniques to characterise materials of moderately high specific activity, such as 99Tc, typically demands use of dedicated instrumentation within a controlled area, to manage contamination.

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Conclusion