Vibrational Satellites of C$_2$S, C$_3$S, and C$_4$S: 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.
