So what (just for the academic exercise of learning about ESR/NMR methods and instruments) are particularly good (i.e. easy) analytic targets
The article I'm sorta being 'inspired' by uses transition metal ions. Fe3+ should be good, along with some others. I think you can also see some larger pi-orbital systems, like conjugated double bonds, carbonyl groups and aromatic rings, but I don't know to what extent.
You're right, the waveguide is just because it'd make a good cavity, and it just so happened that: - the frequency's around 12 GHz, I had a section lying around, and it fits snugly between my magnets, as seen in the image. I'm going to put a gunn diode in one end (either pick up a WR90 mount, or mount it IN the section shown), use that as both freq. gen, and receiver, and thus all the microwave stuff is neatly contained.
I'm still working on how to mount a movable disc in the bottom waveguide blind, but that'll be next week's headache..
Using a thin strip of pcb might be good, it's just tough to mount the sample in. unless you drill a hole, and then press the sample into a disc fitting that exactly..