Fully resolved zeeman pattern in the stern-gerlach deflection spectrum of O2 (3g-, K=1)

The Stern-Gerlach magnetic deflection spectrum of a molecular beam of O216 cooled by supersonic expansion to its lowest rotational level (K=1) reveals nine spatially separated peaks within a span of 2 cm. These peaks readily are assigned from a calculation of the Zeeman energies of the K=1 spin-rotation sublevels characterized by MJ, and the assumption of a uniform field gradient within the deflecting magnet gap. However, the variable widths of the observed peaks and the decreasing deflection of certain MJ peaks with increasing field above 14 kG require the explicit consideration of field-gradient inhomogeneities. The theory for this is developed and the spectral profiles again computed with field-gradient inhomogeneity and rotational temperature (Trot) as variables. Agreement of the theoretical shifts, bandwidths, and relative intensities with increasing field gradient when compared with the experimental spectra is very good, and Trot is found to be 3.5 K. The deflection spectrum of a beam of O217 differs from that of O216, reflecting the population of the K=0 rotational level in the O217 isotopomer. The oxygen dimer and trimer appear to be paramagnetic, but this result is tentative.