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 N¹⁴{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 ${N}^{{-}}$=${O}⁺$. The unpaired electron is shown to be essentially in a $2p$ ${π}$ 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.