Irving Ozier

Theory of the Collision‐Induced Rotational Spectrum of Tetrahedral Molecules

The general theory of induced absorption resulting from binary collisions has been extended and applied to the pressure‐induced far‐infrared spectrum of a gas of tetrahedral molecules. The molecular octopole moment is related to the integrated intensity resulting from the modulation of the octopole‐induced dipole moment by the rotational motion of the molecules. Translational effects are not considered. The intensity resulting from the overlap moment is estimated and found to be negligible. The quantum‐mechanical analysis is presented using both unsymmetrized and symmetry‐adapted wavefunctions. The results are compared, and the limitations of the unsymmetrized approach are discussed. The techniques developed in the symmetrized treatment are generally useful in integrated‐intensity calculations for molecules with a high degree of symmetry and will be discussed in detail. The analysis is applied to recent room‐temperature far‐infrared data on CH4, CD4, and CF4. The octopole moments deduced from the experime...

Construction of Tetrahedral Harmonics

Explicit, detailed, and convenient algorithms have been developed for constructing tetrahedral harmonics for arbitrary J. These functions are expressed as linear combinations of spherical harmonics and also of symmetric top functions. A projection‐operator technique was used to produce projected functions which transform according to the rows of the irreducible matrix representations of Td. In general the set of projected functions so constructed may be linearly dependent. The idempotence of the projection operators was invoked to show that all the required orthonormal tetrahedral harmonics can be produced by the diagonalization of the projection‐operator matrices. The elements of these matrices are given explicitly for arbitrary J. In an Appendix, alternative procedures, including the Gram–Schmidt method, for the orthogonalization of the projected functions are treated briefly, with special emphasis on the use of these matrix elements. The “symmetry‐adapted functions” involve the dK′KJ(π / 2), and a recu...

Pure Rotational Spectrum and Electric Dipole Moment of CH3D

The pure rotational spectrum of CH3D in the ground vibrational and electronic state has been observed using a far‐infrared grating spectrometer. This spectrum is of particular interest because the electric dipole moment μ arises entirely from an isotopic substitution. Ten distinct lines have been observed in the frequency range from 40 to 120 cm−1, and have been identified with the (J → J + 1) transitions for the rotational levels J = 5 − 14. For the (6 → 7) line, the absolute intensity and the linewidth were determined by a curve of growth method. It was found that, for this line, the dipole moment μ = (5.68 ± 0.30) × 10−3D and the broadening parameter γ0 = (0.075 ± 0.012) cm−1/amagat. This measurement constitutes the first correct experimental determination of the dipole moment of CH3D. By making further intensity measurements on other lines, it was shown that, to within 6%, μ is independent of J in the range 5 ≤ J ≤ 12. A detailed account of the experimental methods used to make the intensity measureme...

The importance of methane to pressure-induced absorption in the atmospheres of the outer planets

Pressure-induced absorption in planetary atmospheres from hydrogen-methane collisions, stressing resulting thermal opacity

Low‐Field Hyperfine Spectrum of CH4

The hyperfine spectrum of CH4 has been observed in the low field limit by the molecular‐beam magnetic‐resonance method. Ten partially resolved lines were observed in the frequency region below 100 kHz. The lines associated with the nuclear quintet were found to be equally spaced with frequencies which depend only on the average spin‐rotation constant ca. The lines associated with the nuclear triplet were found to form a complex spectrum with frequencies which depend not only on ca, but also on the anisotropy in the spin rotation matrix cd and on the tensor spin—spin coupling constant d. In the analysis of the triplet spectrum, the energies of the tensor interactions have been calculated in detail by applying the recent group theoretical treatment of Yi, Ozier, and Anderson. It was determined that ca = + (10.4 ± 0.1) kHz; cd = + (18.5 ± 0.5) kHz and d = + (20.9 ± 0.3) kHz. For these values, the calculated and experimental frequencies agree to within a rms deviation of 350 Hz.

Submillimeter spectrum of low-temperature hydrogen - The pure translational band of H2 and the R(0) line of HD

The pure translational absorption spectrum of hydrogen gas has been measured from 20 to 100 cm −1 at temperatures in the range 24-37 K. Superposed on the broad translational band is the sharp rotational line R(0) of HD, present in the gas in natural abundance. From the intensity of the line, the electric dipole moment is determined to be (0.81 ± 0.05) × 10 -3 debye. The measurements are of relevance to the infrared opacity and to the D/H ratio of the atmospheres of the giant planets