Atomic and molecular systems for radiation thermometry

Published

January 15, 2026

Author(s)

Stephen Eckel, Christopher Holloway, Eric Norrgard, Nikunjkumar Prajapati, Noah Schlossberger, Matthew Simons

Abstract

Atoms and simple molecules are excellent candidates for new standards and sensors because they are both all identical and their properties are determined by the immutable laws of quantum physics. Here, we introduce the concept of building a standard and sensor of radiative temperature using atoms and molecules. Such standards are based on precise measurement of the rate at which blackbody radiation (BBR) either excites or stimulates emission for a given atomic transition. We summarize the recent results of two experiments while detailing the rate equation models required for their interpretation. The cold atom thermometer (CAT) uses a gas of laser cooled $^85}$Rb Rydberg atoms to probe the BBR spectrum near 130 GHz. This primary, i.e., not traceable to a measurement of like kind, temperature measurement currently has a total uncertainty of approximately 1 %, with clear paths toward improvement. The compact blackbody radiation atomic sensor (CoBRAS) uses a vapour of $^85}$Rb and monitors fluorescence from states that are either populated by BBR or populated by spontaneous emission to measure the blackbody spectrum near 24.5 THz. The CoBRAS has an excellent relative precision of $u(T)\approx 0.13$ K, with a clear path toward implementing a primary measurement.

Citation

Philosophical Transactions of the Royal Society A-Mathematical Physical and Engineering Sciences

Volume

384

Pub Type

Journals

Download Paper

https://doi.org/10.1098/rsta.2024.0458

Local Download

Keywords

Atomic physics, Molecular physics, Thermodynamics, Thermometry, Blackbody Radiation

Citation

Eckel, S. , Holloway, C. , Norrgard, E. , Prajapati, N. , Schlossberger, N. and SIMONS, M. (2026), Atomic and molecular systems for radiation thermometry, Philosophical Transactions of the Royal Society A-Mathematical Physical and Engineering Sciences, [online], https://doi.org/10.1098/rsta.2024.0458, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=959669 (Accessed May 7, 2026)

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