Thin Cylindrical Sample Positioning In/Out of the Centre of a Bruker Rectangular Cavity
Department of Physical Chemistry, FCHPT STU, Radlinského 9, 812 37 Bratislava, Slovakia
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Abstract: The response of the microwave cavity to the correct (in the cavity centre) versus incorrect (out of the cavity centre) positioning of an “over full-length cavity”, thin cylindrical sample in the Bruker single TE102 rectangular microwave cavity has been analysed. It was concluded that when the sample approaches the “front-back” cavity walls (which corresponds to a shift of the sample centre along the cavity z-axis, Dz), a significant decrease in EPR signal intensity (Ipp) was observed, whereas when the sample approaches the “right-left” cavity walls (which corresponds to a sample shift along cavity y-axis, Dy), a significant increase in the Ipp values was found. Therefore, accurate and precise positioning of each thin cylindrical sample tube, which is filled with powder material or frozen solutions, in the microwave cavity is the principal, necessary and imperative condition in EPR spectroscopy. A special alignment procedure for the accurate and precise positioning of such thin cylindrical samples in the microwave cavity is essential in EPR practice.
Keywords: EPR spectroscopy, sample positioning, thin cylindrical tube, microwave cavity
Full paper in Portable Document Format: acs_0078.pdf
Acta Chimica Slovaca, Vol. 4, No. 1, 2011, pp. 31—37