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The torsion vibrations of (CH3)2X‐type molecules having C2v and Cs point‐group symmetry were analyzed by using a Hamiltonian that includes top—top interaction terms. The energy levels were calculated by first‐order perturbation methods and the selection rules for the infrared‐active transitions were analyzed by group theoretical arguments. Explicit expressions which have been derived for the high potential‐barrier approximation were used to discuss the torsion vibration spectrum of the (CH3)2S molecule.

Specialists in frequency control are improving their crystal vibrators and atomic frequency standards. Toward better crystal devices, they are making filter crystals that operate above 30 Mc/sec; with better mathematical analysis of vibration modes to help, they are using electrode‐thickness tuning and crystal shaping to improve crystal response; they are using sound waves and x rays to investigate vibration‐mode patterns. Some are seeking new materials to replace quartz, especially endowed by nature to function as a frequency standard. Others have used quartz in a new way to make a new kind of delay line. Toward better atomic frequency standards, they are improving both stability and accuracy. All‐solid‐state versions are making rubidium gas‐cell standards and cesium‐beam standards more useful. Other improvements in atomic devices include better circuits for hydrogenbeam tubes, narrower reference lines, and better frequency stabilities, both long‐ and short‐term.

Torsional vibrations of (CH3)3—X type molecules having C3v point group symmetry have been analyzed by using a periodic potential function, and by taking into account mutual top—top interaction terms. The energy scheme was calculated by perturbation methods, and the selection rules have been derived. For the high‐barrier case, two allowed transitions from the ground state to the first excited state can be predicted.

Design parameter and performance of a simple automatic phase‐control system for a GR 1209‐B triode oscillator are described. The frequency modulation of the oscillator was achieved by varying the B+ voltage of the oscillator tube, so that the resonance circuit does not have to be modified, and the described system will change neither the frequency range nor the calibration of the GR 1209‐B oscillator.

The Mainz electron scattering facility provides energies between 80 and 300 MeV and scattering angles up to 158° which corres-pond to a useful momentum transfer region 0.4 ≤ q ≤ 3.0 fm−1. The accelerator and analyzing system produce approximately 1 μA average current with the overall resolution in the final spectra of usually 0.15% to 0.30%.