Electrically Detected Magnetic Resonance Signal Intensity at Resonant Frequencies from 300 to 900 MHz in a Constant Microwave Field
Source: Journal of Magnetic Resonance, Volume 139, Number 2, August 1999 , pp. 422-429(8)
Publisher: Academic Press
Abstract:A method for electrically detected magnetic resonance (EDMR) measurement at different ESR frequencies under a constant alternating magnetic field has been established wherein the accurate relationship between EDMR signal intensity (from a photoexcited silicon crystal and a silicon diode) and a resonant frequency of 300 to 900 MHz (UHF band) was systematically clarified. EDMR signal intensity from a photoexcited silicon crystal against a resonant frequency fitted the curve of y = a(1 - e-bx) well, which approached a constant value at higher frequencies. The increase in the EDMR signal intensity from the silicon diode at higher resonant frequencies was smaller than that from the photoexcited silicon crystal. The difference can be explained by the influence of the skin effect; i.e., the microwaves do not penetrate deep into a highly conductive sample at higher frequencies. EDMR signal intensities of samples vs microwave power were measured at 890 MHz. The EDMR signal intensity from the silicon diode continued to increase as the microwave power was increased, while the signal intensity from the photoexcited silicon crystal saturated within the range. The difference can be similarly explained: due to the skin effect, the microwaves gradually penetrate into the silicon diode as the power increases, so that even when saturation has been reached outside, the microwave field inside the diode does not reach the saturation level.
Document Type: Research Article
Publication date: August 1, 1999