ToF-SIMS Single Beam Depth Profiling and Ion Beam-Induced Hydrophobic Patterning of a Novel Nanoporous Gold Absorber for Decay Energy Spectroscopy

Published

July 10, 2026

Author(s)

Shinichiro N. Muramoto, Robert Verkouteren, Adam Pearce, Ryan Fitzgerald, Denis Bergeron

Abstract

Decay energy spectroscopy relies on the absorber, a small substrate where the radioisotopes are embedded and thermalized, for high counting efficiency and spectroscopic resolution. This absorber in the form of a nanoporous Au was manufactured to prevent the formation of crystals of radionuclides and other impurities that can significantly scatter or dampen the energy of the decay particles, resulting in degraded energy resolution and complex spectral artifacts. In this work, advanced surface analytical tools were used to validate the manufacture and function of a 2.5 µm nanoporous Au absorber. The chemical composition of the alloy was successfully determined to be 99% Au after acid etching using x-ray photoelectron spectroscopy (XPS), formation of the nanoporous structure was visualized using scanning electron microscopy (SEM) and focused ion beam (FIB) to have <100 nm pores with a void space of 38 ± 14 %, and most importantly, time-of-flight secondary ion mass spectrometry (ToF-SIMS) operated in single beam depth profiling was demonstrated for the first time to be an effective method for measuring the transfer and embedding of radionuclides within the Au nanoporous matrix. Some ion bombardment induced artifacts were seen, but the effect was modest and not critical for the visualization of solute into the nanoporous matrix. It was also demonstrated that hydrophobic patterning could be produced on the nanoporous matrix using the equipped ion beam to prevent solution overflow, which was an important quality given that miniaturization of the absorber (e.g., less than 2 mm x 2 mm) was associated with increased signal to noise and reduced tailing.

Citation

Surface and Interface Analysis

Pub Type

Journals

Download Paper

https://doi.org/10.1002/sia.70101

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Keywords

nanoporous gold, decay energy spectroscopy, ToF-SIMS, single beam depth profiling

Citation

Muramoto, S. , Verkouteren, R. , Pearce, A. , Fitzgerald, R. and Bergeron, D. (2026), ToF-SIMS Single Beam Depth Profiling and Ion Beam-Induced Hydrophobic Patterning of a Novel Nanoporous Gold Absorber for Decay Energy Spectroscopy, Surface and Interface Analysis, [online], https://doi.org/10.1002/sia.70101, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=961621 (Accessed September 26, 2026)

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