High-power 95 GHz pulsed electron spin resonance spectrometer

Abstract

Articles you may be interested inA kilowatt pulsed 94 GHz electron paramagnetic resonance spectrometer with high concentration sensitivity, high instantaneous bandwidth, and low dead time Rev. Sci. Instrum. A quasioptical transient electron spin resonance spectrometer operating at 120 and 240 GHz Rev. Sci. Instrum. 76, 074101 (2005);High-field/high-frequency electron spin resonance ͑ESR͒ offers improved sensitivity and resolution compared to ESR at conventional fields and frequencies. However, most high-field/high-frequency ESR spectrometers suffer from limited mm-wave power, thereby requiring long mm-wave pulses. This precludes their use when relaxation times are short, e.g., in fluid samples. Low mm-wave power is also a major factor limiting the achievable spectral coverage and thereby the multiplex advantage of Fourier transform ESR ͑FTESR͒ experiments. High-power pulses are needed to perform two-dimensional ͑2D͒ FTESR experiments, which can unravel the dynamics of a spin system in great detail, making it an excellent tool for studying spin and molecular dynamics. We report on the design and implementation of a high-power, high-bandwidth, pulsed ESR spectrometer operating at 95 GHz. One of the principal design goals was the ability to investigate dynamic processes in aqueous samples at physiological temperatures with the intent to study biological systems. In initial experiments on aqueous samples at room temperature, we achieved 200 MHz spectral coverage at a sensitivity of 1.1ϫ10 10 ͱs spins and a dead time of less than 50 ns.2D-electron-electron double resonance experiments on aqueous samples are discussed to demonstrate the practical application of such a spectrometer.

Toward increased concentration sensitivity for continuous wave EPR investigations of spin-labeled biological macromolecules at high fields

“…To be noted, this value is larger than the reported 0.025 mm aqueous sample thickness at 95 GHz using a Febry-Perot resonator [58]. This is due to the lower finesse (lower Q) of the sample holders used here than the Febry-Perot resonator, which is more sensitive to dielectric losses in the sample and requires smaller optimal sample thickness.…”

Saturation recovery EPR and ELDOR at W-band for spin labels

“…It is doubtful to the authors that some unknown experimental error has occurred. Hofbauer et al [8] report unexpectedly short T 1e values for 1 mM solution of TEMPO in a 10% glycerol-water mixture at W-band and suggest a specific frequency dependent relaxation mechanism involving dynamic modulation of the g-value. These authors call for more detailed studies, as do we.…”

“…The Fourier Transform yields pure EPR absorption and pure dispersion lineshapes, which is advantageous in comparison with the derivative-like lineshapes obtained when magnetic field modulation is used. It is noted that Hofbauer et al [8] also report FIDs from a small nitroxide in water at 94 GHz. It is weaker in intensity by a factor of 10 compared with Fig.…”

“…Since publication of this book, the only article on high-field EPR instrumentation to the best of our knowledge is that of Ref. 8. The papers by Wang et al [9], Nilges et al [10], and Hofer et al [11] focus on continuous wave (CW) EPR, which is used for SR detection, and these papers have provided useful background in the development of the instrument described here.…”

A dual-mode microwave resonator for double electron–electron spin resonance spectroscopy at W-band microwave frequencies

“…An application of a multimode Fabry-Pérot resonator in combination with a W-band high-power system was reported in Ref. [20].…”