Internally amplified stimulated Raman scattering is developed as a nov
el approach to study concentrational thresholds in stimulated Raman sc
attering (SRS). In the proposed physical model, amplifier molecules ar
e used to bridge the spatial gaps among analyte molecules distributed
distantly from each other throughout a dilute solution. As a result, S
tokes photons can more effectively reach the next target molecules dow
n the pump light path to sustain and amplify the desirable SRS process
. The model has been verified by experimental results which give a bet
ter understanding of the threshold phenomenon in SRS. The technique of
internal amplification is practically useful to lower concentrational
thresholds, leading to improved detection limits in analytical SRS me
asurements.