Zeeman Effect in the Rotational Spectrum of NO

The Zeeman splitting of the 2-mm wave, J=1/2→3/2 rotational transit on of N¹⁴O¹⁶ in the ²Π_1/2 electronic state has been measured with fields of the order of 100 gauss. The observations were made with a wave-guide cell coiled between the poles of a Varian magnet. Magnetic field measurements were made with the electronic resonance of DPPH at frequencies of the order of 300 Mc/sec. A general theory of the Zeeman effect with hfs has been developed and applied specifically to N¹⁴O¹⁶. The g factors for the four states under investigation were found theoretically to be expressed as: J=1/2, g_c=0.0007-α, g_d=0.0007+α; J=3/2, g_c=g̅ -2/5α, g_d=g̅ +2/5α, where c and d are the lower and upper components of the Λ-type doublet, respectively. This relation was found to hold experimentally well with the values, g̅ =-0.0230 and α=+0.0025. Theoretically, g̅ comes from the mixing of ²Π_1/2 and ²Π_3/2 states and α comes from that of ²Π_1/2 and ²Σ states. It was found by the theory, in which the centrifugal force and the spin orbit coupling were taken into account, that the electronic wave function of the two rotational states should be: J=1/2, (²Π_1/2|-0.0021(²Σ|; J=3/2, (²Π_1/2|-0.0247(²Π_3/2|-0.0021(²Σ|. These wave functions give g̅ (theor.)=-0.0229 and and α(theor.)=+0.0020, which agree very well with the observed values. The observed g factor in J=3/2 state, g̅ =0.0230 Bohr magnetons, shows that in the supposedly "nonmagnetic" ²Π_1/2 state the NO molecule has a sizeable magnetic moment.