Signal Detection Efficiency in Multiphoton Ionization Flame Measurements
K C. Smyth, P. Tjossem
Resonance-enhanced multiphoton ionization (MPI)has been successfully applied to the detection of numerous free radicals and stable species in flames, including H atom,1 -6 0 atom, 3' 4' 7 C atom, 8'9 CH-,9 CO,5 "10 02,9 NO.W11,1 2 P.,'1 3 CH. 3,8 "145"1HCO.,15,16 C2 0,5 and trans-,3-butadiene.17 Multiphoton ionization methods exhibit high sensitivity and are the only practical optical approach for monitoring minor species when fluorescence quantum yields are low, such as for the methyl (CH3 .) radical. Low fluorescence quantum yields are also expected for larger hydrocarbon radicals of combustion interest, such as ethynyl (C2H-), vinyl (C2H3O), and phenyl (C6H5O). Active investigation to find suitable electronic transitions for MPI detection of these species is currently underway, since they are presently observable only in environments where molecular beam mass spectrometric sampling can be utilized, for example, in low pressure premixed flames.
and Tjossem, P.
Signal Detection Efficiency in Multiphoton Ionization Flame Measurements, Applied Optics, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=912545
(Accessed June 8, 2023)