Magnetic Hyperfine Effects and Electronic Structure of NO

The theory of magnetic hyperfine structure in diatomic molecules is briefly reexamined. Previously reported hyperfine effects in the ${\mathrm{N}}^{14}$ ${\mathrm{O}}^{16}$ molecule, both magnetic and electric quadrupole, are interpreted with corrected theoretical expressions in terms of an electronic structure consisting of 65 percent N=O and 35 percent ${\mathrm{N}}^{-}$=${\mathrm{O}}^{+}$. The unpaired electron is shown to be essentially in a $2p$ $\pi$ orbital but with 2.5 percent $s$ character. Discrepancies of about 8 percent between experimental and calculated values of the magnetic hyperfine constants indicate limitations in the use of atomic wave function approximations for electronic orbitals.