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Even if on-board mm-wave/THz heterodyne receivers have been developed to measure greenhouse gases (GHGs) atmospheric profiles, rotational spectroscopy rests under-exploited for their monitoring unlike IR rovibrational spectroscopy. The present study deals with the ability of THz spectroscopy using long interaction path-lengths for GHG laboratory investigations. High-resolution THz signatures of non-polar greenhouse molecules may be observed by probing very weak centrifugal distortion induced rotational transitions. To illustrate, new measurements on CH<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>4</mn></msub></semantics></math></inline-formula> and CF<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>4</mn></msub></semantics></math></inline-formula> have been carried out. For CH<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>4</mn></msub></semantics></math></inline-formula>, pure rotational transitions, recorded by cw-THz photomixing up to 2.6 THz in a White type cell adjusted to 20 m, have allowed to update the methane line list of atmospheric databases. Concerning CF<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>4</mn></msub></semantics></math></inline-formula>, Fabry-Perot THz absorption spectroscopy with a km effective pathlength was required to detect line intensities lower than 10<inline-formula><math display="inline"><semantics><msup><mrow></mrow><mrow><mo>−</mo><mn>27</mn></mrow></msup></semantics></math></inline-formula> cm<inline-formula><math display="inline"><semantics><mrow><msup><mrow></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup><mo>/</mo><mrow><mo>(</mo><mi>molec</mi><mspace width="3.33333pt"></mspace><msup><mi>cm</mi><mrow><mo>−</mo><mn>2</mn></mrow></msup><mo>)</mo></mrow></mrow></semantics></math></inline-formula>. Contrary to previous synchrotron-based FT-FIR measurements, the tetrahedral splitting of CF<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>4</mn></msub></semantics></math></inline-formula> THz lines is fully resolved. Finally, quantitative measurements of N<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>2</mn></msub></semantics></math></inline-formula>O and O<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>3</mn></msub></semantics></math></inline-formula> gas traces have been performed in an atmospheric simulation chamber using a submm-wave amplified multiplier chain coupled to a Chernin type multi-pass cell on a 200 m path-length. The THz monitoring of these two polar GHGs at tropospheric and stratospheric concentrations may be now considered.