Lowest energy vibrational modes of some naphthalene derivatives: Azulene, quinoline, isoquinoline - Experiment and theory

► First gas phase FIR spectra of azulene, quinoline and isoquinoline. ► Anharmonic DFT calculations. ► Analysis of FIR vibrational modes. ► Comparison of three low-frequency vibrational modes with those of naphthalene.