David J. Meschi

The microwave spectrum, structure, and dipole moment of disulfur monoxide☆

Abstract The microwave spectrum of the product resulting from the passage of an electrical discharge through a mixture of sulfur and SO 2 has been examined. This product, usually called “sulfur monoxide”, was found to have a microwave spectrum which was assigned to disulfur monoxide with a bent SSO structure. The ground state rotational constants were established as A = 41,914.4 0 , B = 5,059.0 9 and C = 4,507.1 4 , Mc/sec. Assignments were also made for an excited vibrational state and for the S 34 S 32 O 16 species. The structure of S 2 O was established as SO 1.46 5 ± 0.010 A, SS 1.88 4 ± 0.010 A, and SSO 118°O′ ± 30′. The components of the dipole moment were established as μ A = 0.875 ± 0.01, μ B = 1.18 ± 0.02 with μ (total) = 1.47 ± 0.02 Debye.

Investigation of the Magnetic Moments of S2, Se2, Te2, Se6, and Se5 by the Stern–Gerlach Magnetic Deflection Method

An apparatus consisting of a Knudsen effusion cell, collimator, inhomogeneous‐field magnet, and quadrupole mass spectrometer has been applied to investigation of the fraction of S2, Se2, Te2, Se6, and Se5 molecules that show a magnetic moment. The expected high concentration of paramagnetic S2 molecules was found, but the concentration of paramagnetic Se2 and Te2 molecules at 1000°K was less than the 10% detection limit. The concentration of paramagnetic Se6 and Se5 at 500°K was unmeasurably low. The results indicate that Se6 and Se5 are not diradicals and that the splittings between the 0g+ ground state and the 1g paramagnetic state of Se2 and Te2 exceed 2000 K. The Se2 data support the conclusion that the dissociation energy of Se2 is 78.63 kcal/mole.

The magnetic moment of Se2

Atoms of the oxygen group form diatomic molecules with a multiplet ground state. Of these, O2 and S2 conform to Hund’s (b) coupling and have an appreciable magnetic moment, whereas Te2 is better described as having case (c) coupling with a very small effective magnetic moment. Although the Se2 molecule is intermediate between these two cases, it is closer to case (c) than to case (b). A method of calculating the magnetic moment and Zeeman effect of a molecule of this series with Hund’s case (c) coupling is described and applied to Se2. The calculations result in a value of 5.97×10−2 μB for the mean effective moment of the Se2 molecule at 1000 K in a field of 14 kG. This value was found to be consistent with the results obtained experimentally by the use of a molecular beam deflection technique similar to that of Stern and Gerlach.