Knowledge Bank

The spectra of the $X2\pi -X2\pi$(1$-$0) transitions of the $\mathrm{<mrow\; data-mjx-texclass="ORD">14</mrow>}N16O,15N16O,14N17O,14N18O$ molecules have been recorded with the molecular Fourier transform interferometer. The resolution $(2.5\times 10-3$ $cm-1)$ allows us to separate the $\Lambda$ doublets in the transitions involving the $\Omega =1/2$ states. The molecular constants have been obtained by numerical diagonalization of the Hamiltonian matrix. The high wavenumber precision permits verification of the excellent agreement for the ratio of the different parameters by isotopic substitution. Effects of various small parameters will be discussed.