The ν1 band system of HCN

► HCN 1463 K hot gas molecular emission spectroscopy. ► 1v2l0→0v2l0 bands up to v2 = 8 and 1v2l1→0v2l1 bands up to v2 = 6. ► 36 HCN rovibronic (v1, v2, l, e/f, v3) substates characterized for the first time; high rotational excitation states up to J = 60-80. ► All l sublevels of v1v2lv3=18l0 highly excited bending combination states. ► Rotational excitation states up to J = 86-2000 cm−1 below the isomerization barrier.