Synchrotron-based far-infrared spectroscopy of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">HC</mml:mi></mml:mrow><mml:mn>3</mml:mn></mml:msub><mml:mi mathvariant="normal">N</mml:mi></mml:mrow></mml:math>: Extended ro-vibrational analysis and new line list up to 3360 cm<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si2.svg"><mml:msup><mml:mrow /><mml:mrow><mml:mo>−</mml:mo><mml:mn>1</mml:mn…

The far-infrared spectrum of HC3N has been recorded at high resolution between 70 and 500 cm−1using synchrotron radiation. Four prominent features, i.e., ν7, ν6−ν7, ν4−ν6, 2ν7 have identified in the together with many associated hot bands. In addition, rotational transitions for interacting v4=v7=1, (v6=2,v7=1), (v5=1,v7=2), v7=5 vibrationally excited states millimeter/submillimeter region. newly assigned transitions, those reported previously, form a comprehensive data set including about 17 000 which involves almost all vibrational lying below 1300 cm−1 plus some energies 2075 3550 cm−1. These fitted to an effective Hamiltonian takes into account l-type resonance effects, number anharmonic interaction terms. On average, analysed are reproduced within experimental accuracy. About 90 ro-vibrational transition frequencies computed on basis spectroscopic constants obtained from global fit order support interpretation astronomical searches interstellar medium planetary atmospheres. Part these is included 2020 release HITRAN database.