V. Majidi et al., Laser-desorption time-of-flight mass-spectrometry analysis of soot from various hydrocarbon fuels, COMB SCI T, 145(1-6), 1999, pp. 37-56
Laser-desorption time-of-flight mass spectrometry (LDMS) was used to analyz
e soot collected from seven different hydrocarbon fuels (methane, n-hexane,
n-heptane, n-octane, n-decane, benzene and toluene) burning with air under
normal atmospheric pressure. To evaluate the technique, samples of two dif
ferent types of furnace blacks, two types of graphite, a synthetic diamond
and a C-70 fullerene also were analyzed. With proper experimental design, t
he C-70 produced a single peak of mass 840 Da. thereby showing the ability
of LDMS to remove and singly ionize large intact molecular species from the
sample for the purpose of chemical analysis. The LDMS soot analysis showed
that each mature soot has a unique chemical fingerprint. A family of fuels
(e.g., normal alkanes) produces soot that is similar in appearance when ma
ture and that therefore might be expected to yield similar mass spectra, bu
t it is found instead that each spectrum has unique features that are diffe
rent for each parent fuel. These initially surprising results point to the
need for further study of fuel pyrolysis in flames.