STERN-GERLACH DEFLECTION SPECTRA OF NITROGEN OXIDE RADICALS.

Magnetic deflection spectra of beams of pure NO sub 2 and NO sub 2 seeded into rare gases have been determined using a Stern- Gerlach apparatus. Using He as carrier, a simple two-line deflection pattern is observed, indicating the breakdown of spin-rotation coupling in fields of 10 kG or more. Use of the other rare gases as carriers yields the two satellites at positions dictated by the beam velocities, and in addition, a more-or-less intense component at zero deflection which we hold to be due to diamagnetic or weakly paramagnetic (NO sub 2) sub x clusters. The deflection amplitudes and line shapes are in good agreement with calculations. Additional weak bands observed in the spectra are likely due to van der Waals clusters such as NO sub 2 - Ar and NO sub 2 - Ne. sup (14) N / sup (15) N isotope effects in NO sub 2 were visible as changes of line shape. Zeeman level anticrossings are calculated quantum mechanically to occur for NO sub 2 in the 20-30 kG regime, however their effects are small and were not observed. Deflection spectra of NO in its sup 2 PI sub (3 / 2) thermally excited state were obtained showing satellites at the positions predicted assuming no coupling between S and K . Modeling of the observed spectra shows that both the electronic and rotational temperatures of the NO in the beam are rather high (20-125K). The magnetic deflection spectra of the dialkyl nitroxide TEMPO observed here argue against the suggestion of Amirav and Navon [(Chem. Phys. 82, 253(1983)] that this molecule undergoes significant intramolecular spin-lattice relaxation while in the magnet gap.