jp0c02919_si_002.pdf (2.45 MB)
Exhaustive Product Analysis of Three Benzene Discharges by Microwave Spectroscopy
journal contribution
posted on 2020-06-12, 12:04 authored by Michael C. McCarthy, Kin Long Kelvin Lee, P. Brandon Carroll, Jessica P. Porterfield, P. Bryan Changala, James H. Thorpe, John F. StantonUsing chirped and
cavity microwave spectroscopies, automated double resonance, new high-speed
fitting and deep learning algorithms, and large databases of computed
structures, the discharge products of benzene alone, or in combination
with molecular oxygen or nitrogen, have been exhaustively characterized
between 6.5 and 26 GHz. In total, more than 3300 spectral features
were observed; 89% of these, accounting for 97% of the total intensity,
have now been assigned to 152 distinct chemical species and 60 of
their variants (i.e., isotopic species and vibrationally excited states).
Roughly 50 of the products are entirely new or poorly characterized
at high resolution, including many heavier by mass than the precursor
benzene. These findings provide direct evidence for a rich architecture
of two- and three-dimensional carbon and indicate that benzene growth,
particularly the formation of ring–chain molecules, occurs
facilely under our experimental conditions. The present analysis also
illustrates the utility of microwave spectroscopy as a precision tool
for complex mixture analysis, irrespective of whether the rotational
spectrum of a product species is known a priori or
not. From this large quantity of data, for example, it is possible
to determine with confidence the relative abundances of different
product masses, but more importantly the relative abundances of different
isomers with the same mass. The complementary nature of this type
of analysis to traditional mass spectrometry is discussed.