SERS, Surface enhanced raman spectroscopy, using AgNPs

solas99

this is kind of a spectroscopy question, basically i collected a Raman spectrums for rhodamine(dye) enhanced by silver nano particles.
Im trying to quantify the Analytical enhancement factors (AEF)/surface enhancement factors(SEF).
My question is,how do i get the raman cross-section? i already have the spectra, but dont know what they mean by the raman cross-section? is it the area under the peaks?

and in what manner do i place the baseline points?

appreciate any help.