Neutral product analysis of the microwave C2H2 plasma: Cn, CnH2, CnH3, CnH4, CnH5, and larger species

Product analysis of microwave (MW) C2H2 discharge by Li+ ion attachment mass spectrometry demonstrates the unexpected formation of many unfamiliar hydrocarbon neutral products. The experiments were conducted under MW discharge conditions in which the peak intensities for the ionic species leaving the MW C2H2 plasma were barely detectable which permits confirmation of these neutral compound in the gas phase. Various free radicals as well as stable polymer molecules were clearly present. The latter are classified as Cn (n=4, 6, and 8), CnH2 (n=2, 3, 4, 6, and 8), CnH4 (n=2, 3, 4, 6, and 8), and so on, where n is the carbon number. Radicals such as CnH3 (n=2 and 4), CnH5 (n=2, 4, and 6), CnH7 (n=3 and 4), and CnH9 (n=4) were detected. Some of these species, which have been observed in the interstellar space, have been identified mass spectrometrically for the first time. We believe that integrating a Li+ ion attachment reactor with quadrupole mass spectrometry can create a powerful instrument for installation on spacecraft. copyright 1997 American Institute of Physics