Signatures of rare-earth elements in mineralogical form using laser-ablation dual-comb spectroscopy
Abstract
Spectroscopy of laser-produced plasmas offers an avenue for real-time, standoff and non-preparatory sensing of rare-earth elements (REEs) within a mineralogical context with applications spanning exploration geology to ore body mapping to ore sorting. Demonstrations of laser-induced breakdown spectroscopy (LIBS) in rock samples have employed both atomic and molecular detection for REE sensors. In this work we evaluate a complementary technique of absorption spectroscopy, realized with dual-frequency combs. This approach provides multi-THz (nm) spectral coverage with simultaneous sub-GHz (pm) resolution. It can improve accuracy and line identification confidence in congested multi-species spectra, which makes it ideal for multi-species evaluations present within mineralogical samples. We analyze REE signatures in calibrated reference materials (CRMs) and a synthesized, REE-containing alloy for atomic, ionic and molecular (oxide) absorptions across three spectral windows. We identify lines from rare-earth and matrix elements, compare absorption line strengths and investigate their temporal evolution. For La I, Sm I and Ce I, preliminary limits of detection from 54-583 ppm are estimated for CRMs, using univariate analysis of selected transitions. Comparing the CRM signatures to those of REEs synthesized in a copper alloy, we observe that all REE lines appear earlier and disappear faster in the CRM samples. We attribute these dynamics to matrix effects: Among other elements, the increased oxygen content in the CRM could favor molecular formation. For rock samples, observations will once again differ due to grain sizes and bonding mechanisms. Compared to LIBS, we can resolve individual REE and matrix lines with minimal spectral overlap. These proof-of-principle results form a foundation for further development of this laser-based method as a mining sensor.
Versions
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BibTeX
@misc{hofer2026signatures,
title = {{Signatures of rare-earth elements in mineralogical form using laser-ablation dual-comb spectroscopy}},
author = {Christina Hofer and Errol Bowman and Andrew Jarymowycz and John J. McCauley and Dylan Tooley and Hope Dannar and Avery Wong and Ian Pang and Arthur K. Mills and Mark Phillips and R. Jason Jones and David J. Jones},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2605.03157},
eprint = {2605.03157},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2605.03157},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Signatures of rare-earth elements in mineralogical form using laser-ablation dual-comb spectroscopy
AU - Christina Hofer
AU - Errol Bowman
AU - Andrew Jarymowycz
AU - John J. McCauley
AU - Dylan Tooley
AU - Hope Dannar
AU - Avery Wong
AU - Ian Pang
AU - Arthur K. Mills
AU - Mark Phillips
AU - R. Jason Jones
AU - David J. Jones
PY - 2026
DA - 2026/10/05
PB - arXiv
DO - 10.48550/arxiv.2605.03157
UR - https://arxiv.org/abs/2605.03157
AB - Spectroscopy of laser-produced plasmas offers an avenue for real-time, standoff and non-preparatory sensing of rare-earth elements (REEs) within a mineralogical context with applications spanning exploration geology to ore body mapping to ore sorting. Demonstrations of laser-induced breakdown spectroscopy (LIBS) in rock samples have employed both atomic and molecular detection for REE sensors. In this work we evaluate a complementary technique of absorption spectroscopy, realized with dual-frequency combs. This approach provides multi-THz (nm) spectral coverage with simultaneous sub-GHz (pm) resolution. It can improve accuracy and line identification confidence in congested multi-species spectra, which makes it ideal for multi-species evaluations present within mineralogical samples. We analyze REE signatures in calibrated reference materials (CRMs) and a synthesized, REE-containing alloy for atomic, ionic and molecular (oxide) absorptions across three spectral windows. We identify lines from rare-earth and matrix elements, compare absorption line strengths and investigate their temporal evolution. For La I, Sm I and Ce I, preliminary limits of detection from 54-583 ppm are estimated for CRMs, using univariate analysis of selected transitions. Comparing the CRM signatures to those of REEs synthesized in a copper alloy, we observe that all REE lines appear earlier and disappear faster in the CRM samples. We attribute these dynamics to matrix effects: Among other elements, the increased oxygen content in the CRM could favor molecular formation. For rock samples, observations will once again differ due to grain sizes and bonding mechanisms. Compared to LIBS, we can resolve individual REE and matrix lines with minimal spectral overlap. These proof-of-principle results form a foundation for further development of this laser-based method as a mining sensor.
ER -