Design considerations of a dual mode X-band EPR resonator for rapid in-situ microwave heating

Barter, Michael ORCID: https://orcid.org/0000-0002-4404-9397, Magri, Giuseppina, Harari, Jaafar, Choi, Heungjae ORCID: https://orcid.org/0000-0003-1108-293X, Folli, Andrea ORCID: https://orcid.org/0000-0001-8913-6606, Slocombe, Daniel R. ORCID: https://orcid.org/0000-0003-3590-6075, Richards, Emma ORCID: https://orcid.org/0000-0001-6691-2377, Murphy, Damien M. ORCID: https://orcid.org/0000-0002-5941-4879 and Porch, Adrian ORCID: https://orcid.org/0000-0001-5293-8883 2022. Design considerations of a dual mode X-band EPR resonator for rapid in-situ microwave heating. Applied Magnetic Resonance 53 , pp. 861-874. 10.1007/s00723-022-01463-1

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Abstract

This paper describes the design considerations for a dual mode X-band continuous wave (CW) Electron Paramagnetic Resonance (EPR) cavity, for simultaneous EPR measurement and microwave heating of the same sample. An elliptical cavity geometry is chosen to split the degeneracy of the TM110 mode, allowing for a well resolved EPR signal with the TM110,a and TM110,b modes resonating at around 10 GHz and 9.5 GHz, respectively, the latter of which is used for EPR measurements. This geometry has the benefit that the TM010 mode used for microwave heating resonates at 6.1 GHz, below the cut off frequency of the X-band waveguide used for the EPR channel, providing effective isolation between the heating and EPR channels. The use of a pair of 9 µm thick copper clad laminates as the flat cavity walls allows for sufficient penetration of the modulation field (Bmod) into the cavity, as well as maintaining a high cavity Q factor (> 5700) for sensitive EPR measurements. Locating the heating port at an angle of 135° to the EPR port provides additional space for easier coupling adjustment and for larger sample access to be accommodated. The associated decrease of EPR signal strength is fully compensated for by using a 7.2 GHz low pass filter on the heating port. EPR spectra using 1.6 mm and 4.0 mm sample tubes are shown at room temperature (298 K) and 318 K for a standard Cu(acac)2 solution, demonstrating the effectiveness of this dual-mode EPR cavity for microwave heating during EPR detection.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Engineering Chemistry
Additional Information:	This article is licensed under a Creative Commons Attribution 4.0 International License
Publisher:	Springer
ISSN:	0937-9347
Funders:	EPSRC
Date of First Compliant Deposit:	27 January 2022
Date of Acceptance:	14 January 2022
Last Modified:	16 Oct 2024 10:20
URI:	https://orca.cardiff.ac.uk/id/eprint/147007

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