LASER-INDUCED FLUORESCENCE DETECTION STRATEGIES FOR SODIUM ATOMS AND COMPOUNDS IN HIGH-PRESSURE COMBUSTORS

A variety of laser-induced fluorescence schemes were examined experime ntally in atmospheric pressure flames to determine their use for sodiu m atom and salt detection in high-pressure, optically thick environmen ts. Collisional energy transfer plays a large role m fluorescence dete ction. Optimum sensitivity, at the parts in 10(9) level for a single l aser pulse, was obtained with the excitation of the 4p-3s transition a t 330 nm and the detection of the 3d-3p fluorescence at 818 nm. Fluore scence loss processes such as ionization and amplified spontaneous emi ssion were examined. A new laser-induced atomization/laser-induced flu orescence detection technique was demonstrated for NaOH and NaCl. A 24 8-nm excimer laser photodissociates the salt molecules present in the seeded flames prior to atom detection by laser-induced fluorescence.