Microwave transparent material for ESR/EPR spectrometer

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SUMMARY

The discussion focuses on selecting a suitable microwave transparent material for an electron spin resonance (ESR) and electron paramagnetic resonance (EPR) spectrometer operating at X-band frequencies (~12GHz). The user is considering a sintered magnesium oxide (MgO) rod for the sample holding mechanism but is advised to explore alternatives such as Teflon, styrene, or fused quartz. Key considerations include minimizing detuning through low dielectric constant materials and maintaining a high cavity Q with low loss tangent materials. The necessity of retuning the cavity upon any internal adjustments is also emphasized.

PREREQUISITES
  • Understanding of electron spin resonance (ESR) and electron paramagnetic resonance (EPR) principles
  • Familiarity with microwave waveguide technology
  • Knowledge of material properties, specifically dielectric constants and loss tangents
  • Experience with cavity tuning techniques in microwave applications
NEXT STEPS
  • Research the properties of Teflon, styrene, and fused quartz for microwave applications
  • Learn about the effects of dielectric materials on cavity Q in ESR/EPR setups
  • Investigate techniques for retuning microwave cavities after sample adjustments
  • Explore the fabrication processes for sintered MgO and its applications in spectrometry
USEFUL FOR

This discussion is beneficial for physicists, engineers, and hobbyists involved in the design and construction of ESR/EPR spectrometers, particularly those seeking to optimize material choices for microwave transparency and cavity performance.

C.Braestrup
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Hi! Completely forgot about this great forum!

I'm designing an electron spin resonance /electron paramagnetic resonance spectrometer, as an easier vacation from my diy NMR - while still utilizing much of the same setup.

Issue is; I have an X-band (~12GHz) waveguide cavity in a magnet, and I need to be able to adjust the position of a sample in that waveguide without ruining or detuning my cavity. There'll be a bushing in one of the WG shorts with which to rotate the sample eccentrically, but what material should the sample holding rod be?

I'm not really keen on making it from beryllia... The article I'm kinda following is putting the sample ions in a MgO matrix, would a little sintered MgO rod be the answer?

Thanks in advance!
 
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These are impressive DIY projects! I would think a low dielectric constant is desirable to minimize detuning, and a low loss tangent is necessary to keep the cavity Q high. I suggest starting with teflon, which has that combination, or looking at styrene or fused quartz if you need a more rigid material. Your cavity will probably need to be retuned if you move anything inside, no matter what.
 

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