Near-Infrared Phosphorescence of Raman Photogenerated Singlet Oxygen

We report on the phosphorescence of singlet oxygen photogenerated through a stimulated Raman process. Nanosecond radiation in the green spectral region focused on hexane and carbon tetrachloride induces a Raman transition of the dissolved solvent oxygen molecules towards the singlet oxygen state, producing a Stokes signal in the near-infrared. The excited oxygen relaxes to the ground, emitting an infrared photon at 1272 nm. While the Stokes signal’s wavelength changes with the light’s wavelength, the wavelength of the phosphorescent photon remains unaltered. The result confirms previous reports on the stimulated Raman excitation of singlet oxygen.