Studies of a fuel-rich propane flame with photoionization mass spectrometry

Flame-sampling photoionization mass spectrometry, using continuously tunable synchrotron radiation, offers important advantages for studies of flame chemistry. Mole fraction profile measurements for 24 flame species are presented for a fuel-rich low-pressure premixed laminar C 3H 8/O 2/Ar flame. Near-threshold photoionization efficiency measurements provide selective detection of individual isomers and unambiguous identifications of other flame species of near-equal mass. The absolute molar composition of the allene and propyne isomers of C 3H 4 was determined. Absolute cross-sections for photoionization of C 2H 2, C 2H 4, CH 3OH, C 3H 4 (propyne), CH 3CHO, (CH 3) 2CO, and C 6H 6 were used to determine molecular beam mass discrimination factors valid for ion masses ranging from 26 to 78 amu.