The acetylene ground state saga

The evolution of high-resolution spectroscopic investigation of the vibration–rotation energy states of acetylene in its ground electronic state is presented, focusing on advances co-authored by the ULB group. The emergence of a global picture accounting for all available spectroscopic fingerprints, at their full accuracy, is highlighted. The contributions of this research to various topics is illustrated, including instrumental developments, local mode trends, quantum vs. classical correspondence, energy vs. time approaches and nucleation processes.