Dear who it may concern, could anyone tell me what the detection depths of EPR and Raman are, respectively? It would be best if there are literatures support.
bset regards
puxian
hku
Raman happens there where your laser focus is. If your material is almost transparent at the laser wavelength you are applying, you can go as deep as the refractive index allows you to go without losing focus. That could in principle go up to a cm range, although I doubt that would work for a powder which should have too much scattering. If it absorbs significantly, the penetration depth building on the absorption coefficient provides an orientation.
EPR uses radiation in the GHz region which has an extremely high penetration depth since it barely gets absorbed unless you go to extremely high spin densities. In these guidelines by Caltech, a maximum optical density of 1.8 mm is recommended for their setup:
https://cce.caltech.edu/documents/3759/EPR_sample_guide_EvoKG4I.pdf
Please be aware that such numbers depend on the spectrometer.
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