  We present an in-depth analysis of the experimental estimation of cross
sections in Surface Enhanced Raman Scattering (SERS) by vibrational pumping.
The paper highlights the advantages and disadvantages of the technique,
pinpoints the main aspects and limitations, and provides the underlying
physical concepts to interpret the experimental results. Examples for several
commonly used SERS probes are given, and a discussion on future possible
developments is also presented.
