we have epr in-phase signal when phase of modulation field coincide with reflected wave from resonator, and quadrature one when modulation field and reflected wave from resonator deferent from each other 90 deg.
We irradiated powder of nanodiamond by ultraviolet light. After that epr experiment was conducted. This cycle was repeat some times. Then we found inversion when in-phase signal was recorded. (all measurements were at room temperature)
What can happen in this case?
Thank you so much!
Maybe you have a strong change in relaxation times of the system studied and you started to register the mixture in-phase and quadrature signals. You can try to reduce the microwave power and/or to reduce the modulation frequency of the magnetic field.
There are two "phase setting" in EPR spectrometer.
One is the phase setting of the microwave in the homodyne system.
Another is the phase setting of the lock-in detection.
If you want to do the latter, you have to prepare a reference paramagnetic sample with a short relaxation time which must have broad line-width and must be hard to saturate.
Set the lock-in phase as the out-of-phase signal be zero.
Then I think your inverse signal will turn to be normal, probably almost zero.
Once I sometimes got such inverse signals of E' center, SO3- signal etc. in irradiated samples.
I have new synthesic sample. I have not known yet the relaxation time of paramagnetic ceters of it. My modulation frequency is constant (100kHz). What should i do to test the phase setting of in phase and out-90-of phase, if the experience is limitted by room temperature and continuous regime of measurement?
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