Anomalous anti-Stokes Scattering in Amorphous Carbon Thin Films

This work is devoted to a study of temperature-dependent Raman scattering of amorphous carbon (a-C) thin films. An anomalous rise of the anti-Stokes intensity in respect to the Stokes intensity was observed. This result comes from the resonant enhancement of anti-Stokes scattering of defects of graphite-like crystals. The observed discrepancy is quantified through a coefficient, a, defined as a ratio of the anti-Stokes and Stokes scattering cross sections. Understanding the mechanism for anomalous enhancement of anti-Stokes scattering provides a way for correct probing the temperature of the a-C thin films exposed to cw laser illumination.