Stimulated Raman Method for Efficient Generation of Enhancer-Free Singlet Oxygen
Abstract
Singlet oxygen is the molecule of oxygen at its lowest excited electronic level. The molecule is chemically active, being able to break covalent bonds of complex organic molecules. The singlet oxygen method has been applied for photoinactivation of viruses and bacteria, photodynamic cancer treatment, photo-disinfection of pharmaceutical products and blood, water conservation research, and protein studies, among other remarkable applications. The standard procedure uses photosensitizers which absorb the visible photons and transmit energy toward the excitation of the surrounding oxygen molecules. We have recently demonstrated that the singlet oxygen can be excited through induced Raman scattering. This new approach does not require the use of photosensitizers. While quantum mechanics forbids directly visible light excitation of the singlet oxygen state, quantum mechanics selection rules allow Raman to transition from the ground toward the singlet oxygen level. Using blue light, we detected Stokes signals from oxygen dissolved in water in the red spectra corresponding to the singlet oxygen energy level. The current proposal will confirm the Raman method validation by performing detection of the singlet oxygen s phosphorescence. The proposal also explores the utility of this finding to optimize singlet oxygen production for practical applications. We will investigate the exponential character of the induced Raman signal by varying the intensity of the pumping light, increasing the volume of interaction, increasing the oxygen concentration, and using a seeding continuous wave light at the singlet oxygen s Stokes frequency to promote the Raman interaction. We will apply water electrolysis to increase the sample s oxygen concentrations. We propose increasing the interaction path length by using a polystyrene fiber filled with water. We also will study the possible induced Raman effect in the air under normal conditions for environmental photo-disinfection and virus photoinactivation applications. Thanks to a recent DOD equipment grant, we have the necessary equipment to complete the task (application No 78038-RT-REP). The equipment includes an optical parametric oscillator emitting high-intensity nanosecond pulses. The system is tunable in ultraviolet, visible, and near-infrared. We also have a high sensitivity spectrophotometer aided with a photon counting technology to perform phosphorescence studies. The program will promote the training of graduate and undergraduate students funded by parallel programs. We will conduct the research in the laboratory of Quantum Optics at Delaware State University, an HBCU institution with a significant tradition of serving underrepresented and underserved communities. We will encourage the participation of minority students in the program, taking advantage of the character of the university.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- May 24, 2023
- Source ID
- W911NF2310245
Entities
People
- A. Marcano
Organizations
- Army Contracting Command
- Delaware State University
- Office of the Secretary of Defense