Vibrational satellites of C2S, C3S, and C4S: microwave spectral taxonomy as a stepping stone to the millimeter-wave band

We present a microwave spectral taxonomy study of several hydrocarbon/CS 2 discharge mixtures in which more than 60 distinct chemical species, their more abundant isotopic species, and/or their vibrationally excited states were detected using chirped-pulse and cavity Fourier-transform microwave spectroscopies. Taken together, in excess of 85 unique variants were detected, including several new isotopic species and more than 25 new vibrationally excited states of C 2 S, C 3 S, and C 4 S, which have been assigned on the basis of published vibration-rotation interaction constants for C 3 S, or newly calculated ones for C 2 S and C 4 S. On the basis of these precise, low-frequency measurements, several vibrationally exited states of C 2 S and C 3 S were subsequently identified in archival millimeter-wave data in the 253-280 GHz frequency range, ultimately providing highly accurate catalogs for astronomical searches. As part of this work, formation pathways of the two smaller carbon-sulfur chains were investigated using 13 C isotopic spectroscopy, as was their vibrational excitation. The present study illustrates the utility of microwave spectral taxonomy as a tool for complex mixture analysis, and as a powerful and convenient 'stepping stone' to higher frequency measurements in the millimeter and submillimeter bands. We present a microwave spectral taxonomy study of several hydrocarbon/CS 2 discharge mixtures, in which more than 60 distinct species/vibrational states were detected and analyzed.