Forbidden rotational spectra of polyatomic molecules: Stark effects and Δ J = 0 transitions of Td molecules

Abstract

The Δ J = 0 matrix elements of the centrifugally induced dipole moment of tetrahedral molecules in the ground vibrational state are examined. The predicted effects of these matrix elements are linear Stark effects of the E rotational levels and a complicated pure rotational spectrum in the radiofrequency and microwave regions. Tables of the centrifugal fine-structure splitting function, the linear Stark coefficients, and the line strengths of the E- E transitions and the stronger A- A and F- F transitions are presented for J values up to 20. The possible observation of these effects in methane is discussed.