Hyperfine Structure in the Microwave Spectrum of HDO, HDS, CH2O, and CHDO : Beam-Maser Spectroscopy on Asymmetric-Top Molecules

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Abstract
Hyperfine structure in the 220→221 rotational transition of HDO at 10 278.2 Mc/sec and HDS at 11 283.8 Mc/sec, and in the 211→212 rotational transition of CH2O at 14 488.6 Mc/sec and CHDO at 16 038.1 Mc/sec, has been investigated with a high‐resolution beam maser microwave spectrometer. Linewidths of 5 kc/sec have been obtained. The hyperfine Hamiltonian for an arbitrary number of nuclei with quadrupole, spin—rotation, and spin—spin interactions is discussed, and the matrix elements of the Hamiltonian and the intensities of hyperfine transitions calculated in terms of the tabulated 6j coefficients. Quadrupole and spin—rotation constants and bond lengths which have been determined are, for the 220 state of HDO: (eqJQ)D = 79.3±0.3 kc/sec, CH = —43.47±0.11 kc/sec, CD = —2.33±0.02 kc/sec; for the 221 state of HDO: (eqJQ)D = 79.6±0.3 kc/sec, CH = —43.63±0.13 kc/sec, CD = —2.20±0.02 kc/sec; for the 220 state of HDS: (eqJQ)D = 42.9±0.4 kc/sec, CH = —25.03±0.13 kc/sec, CD = —0.47±0.02 kc/sec; for the 221 state of HDS: (eqJQ)D = 43.3±0.4 kc/sec, CH = —25.45±0.13 kc/sec, CD = —0.22±0.02 kc/sec; for CH2O: CH (211) — CH (212) = 2.26±0.13 kc/sec, CH (211) = 0.65±0.50 kc/sec, 〈1/rHH3〉—⅓ = 1.898±0.017 Å; for CHDO: (eVξξQ)D = 170.0±2.0 kc/sec (where Vξξ is the second derivative of the electrostatic potential along the CD bond), CH (211) — CH (212) = 2.42±0.50 kc/sec, CD (211) — CD (212) = 0.25±0.10 kc/sec, CH (211) = 0.2±1.0 kc/sec, CD (211) = 0.13±0.20 kc/sec, and 〈1/rHD3〉—⅓ = 1.88±0.10 Å. The Vξξ calculated from the deuteron quadrupole coupling constants are, for HDO: 1.56×1015 statvolt/cm2; for HDS: 0.76×1015 statvolt/cm2; and for CHDO: 0.83×1015 statvolt/cm2.