Confirming the stimulated Raman origin of singlet-oxygen photogeneration

Authors: MARCANO-OLAIZANO, A - Delaware State University; ZERRAD, AMEEN - Delaware State University; JANNETO, FAHIM - Delaware State University; Kingsley, David

Submitted to: Journal of Raman Spectroscopy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/9/2023
Publication Date: 10/25/2023
Citation: Marcano-Olaizano, A., Zerrad, A., Janneto, F., Kingsley, D.H. 2023. Confirming the stimulated Raman origin of singlet-oxygen photogeneration. Journal of Raman Spectroscopy. https://doi.org/10.1002/jrs.6615.
DOI: https://doi.org/10.1002/jrs.6615

Interpretive Summary: Previously production of singlet oxygen was demonstrated in distilled water using laser light, a fundamental scientific finding. In this publication we confirm that the mechanism of production for singlet oxygen is Raman scattering by characterizing emitted light patterns. Singlet oxygen, generated from light, is important because it is nature’s "disinfectant" capable of inactivating pathogenic organisms.

Technical Abstract: We confirm the Raman origin of the singlet oxygen photogenerated in water environments without the use of photosensitizers. Nanosecond light pulses in the blue region of the spectra (405-480 nm) generate Raman Stokes excitation of singlet oxygen in the red region (600-670 nm) when focusing on pure distilled water. The excitation also generates Stokes components corresponding to the stretching modes of water molecules. The time evolution of both types of Stokes components, singlet oxygen and stretching modes, are similar corresponding to the time duration of the excitation pulse as expected for a Raman process. Their power dependences are also similar. Finally, both signals exhibit high refractive ring structures, due to the optical nonlinear refraction generated by the stimulated Raman process.