Using electron spin resonance (ESR), the g-factor, and lifetime of the spin-flip state of the unpaired electron in 1,1-diphenyl-2-picryl-hydrazyl (DPPH) was determined. To aid with the understanding of the principles involved a resonance profile for a passive RF circuit was also created.
Initially, a simple RF circuit was analysed. The ESR unit, shown in figure 2 was connected to the active coil. A passive coil was connected to an oscilloscope and placed inline with the active coil at a small distance. At the resonant frequency, the current passing through the driving coil was damped, and as such the voltage and current in the coil decreased. Conversely, a greater EMF was induced in the passive coil. As the frequency was varied, the peak-to-peak voltage was recorded in the passive coil. The current through the active coil was also measured and was be used to infer the voltage in the active coil. The resonance profile was recorded with approximately 1 mm, 1 cm and 15 cm separations between the active and passive coil.
DDPH was then analysed.
ESR (Electron Spin Resonance) was used to determine the Landé factor for DPPH. The value of 1.74 ± 0.1 was 13% lower than the literature value of 2.0036. There was a 15% uncertainty in the DC current required to produce resonance, which is the most probable cause of this error. Despite this discrepancy, the Earths magnetic field was measured and was consistent with the literature value found.
The electron spin-flip lifetime for DPPH was calculated to be (9.0 ± 0.2) × 10−9 s.