Phonon-assisted anti-Stokes luminescence of tricarbocyanine near-infrared dye

Abstract

Hot-band absorption assisted anti-Stokes photoluminescence (ASPL) in the near infrared region is demonstrated using specific tricarbocyanine dye, with the large anti-Stokes shift of 100 nm. Intensity of the ASPL is shown to correlate with intensity of the hot-band absorption through population of the vibronic levels during heating. CCC bending of the molecular backbone is shown to be the dominant vibronic mode to assist in the above phenomenon. As a proof-of-principle, laser cooling effect for this new type of molecules is demonstrated, with net cooling power of about 1 mW per 100 mW of the pumping power, or cooling efficiency of 1%.