A laser system and method employing stimulated Raman scattering using a main laser pulse and a delayed replica reference pulse are provided. A further aspect calculates stimulated Raman loss and stimulated Raman gain from a reflected laser light scatter collected from a fabric or paper specimen. In another aspect, a laser system receives a low energy portion of a spectrum of main and reference laser pulses with a first photodetector, receives a higher energy portion of the spectrum of the main and reference pulses with a second photodetector, and uses a controller to determine a Raman active phonon transfer of energy manifested as an increase in the reflected laser scatter in a lower energy portion of the spectrum and a decrease in a higher energy portion of the spectrum. In yet another aspect, the controller automatically determines if a hazardous particle or substance such as an explosive, is present on a specimen.