Knowledge Bank

New wavelength standards are obtained in the $2000cm-1$ spectral region. They consist of lines belonging to the vibration-rotation spectra of $H2O$, $CO2$, CO molecules and some of their isotopic species. Their measurement has been performed with reference to the krypton - 84 Length Etalon by using 2-0 CO band lines previously determined on the same apparatus with an estimated relative error of 3 $\times$ 10$\mathrm{<mrow\; data-mjx-texclass="ORD">-8</mrow>}$.