Measurements and analysis of atomic emission from atomic Li, Na, and K seeded in different flames for potential application to temperature sensing

Abstract: Alkali metal atoms, especially sodium and potassium, show an intense fluorescence in hot flue gases. The bright fluorescence emitted by alkali metal atoms offers a large potential for spectroscopic combustion analysis. In this thesis, the temperature dependence of the two-component fluorescence intensity ratio Na/K, as well as the three-component ratio Na·Li/K2 was investigated in the flames with known relative concentrations of seeded alkali elements. A theoretical simulation based on thermal radiation excitation was performed to describe the temperature dependence of fluorescence intensity ratios Na/K and Na·Li/K2 in burned gas region. However, measurements show that the two-component fluorescence intensity ratio Na/K is pretty sensitive to the gas temperature whereas the three-component ratio Na·Li/K2 is less temperature dependent. The hot flue gas environment was provided by a modified Perkin-Elmer burner and the alkali metal atoms (Na, K, and Li) were provided through Na2CO3, K2CO3, and Li2CO3 water solution seeding.