Dipole Moment and Electric Quadrupole Effects in HNCO and HNCS

Interaction of the electric quadrupole moment of the nitrogen nucleus with the molecular electric fields of isocyanic and isothiocyanic acids results in a hyperfine splitting of the rotational trnasitions

A Linear Current Regulator

Conventional vacuum-tube current regulators are effective in maintaining a current at a predetermined value, accounting for their widespread use in the familiar electronically regulated power supplies. In some applications, however, it is desirable to have the controlled current respond literally (or in some other specified fashion) to changes in some mechanical controlling device; and the ordinary circuits do not satisfy this condition, since their linearity depends upon that of an associated dc amplifier. To be sure, any desired approximation to linearity can be obtained by increasing the gain of this amplifier, but for many purposes a sufficiently linear regulator of adequate stability becomes unnecessarily complex. The simple circuit described here is novel in that its linearity depends upon that of no element except a single helical potentiometer, which is inexpensively available to linearity tolerances of 0.1 percent or better

The Structure of Trifluoromethyl Acetylene from the Microwave Spectrum and Electron Diffraction Pattern

Measurements, in the microwave region, of the J = 3→4 rotational transitions of trifluoromethyl acetylene and several of its isotopic modifications have been made, and the moments of inertia, I_B (in a.m.u.‐Å 2), have been found for the ground vibrational state: for CF_3CCH, 175.61_3, CF_3C^(13)CH, 177.02_4, CF_3CC^(13)H, 181.30_2, and for CF_3CCD, 187.46_2. Three lines corresponding to J = 3→4 transitions of CF_3CCH in the excited vibrational state v_(10) = 1, and two lines corresponding to v_(10) = 2 and v_(10) = 3, have also been measured and interpreted according to Nielson's theory of l‐type doubling in symmetric tops. From Stark effect measurements at different electric field strengths the dipole moment of CF_3CCH in the ground vibrational state has been found to be 2.36±0.04 Debye units. For the ground vibrational state the microwave data lead to the following bond distances: C–H, 1.056±0.005Å; C≡C, 1.201±0.002A. The C–C and C–F distances were calculated from the measured moments of inertia for several assumed values of the FCF angle. Electron diffraction experiments were also made, and the intensity curves calculated for the assumed microwave models were compared with the observed visual curve. From the combination of microwave and electron diffraction results the best agreement was obtained with the following set of parameters: ∠FCF, 107.5°±1°; C–C, 1.464±0.02A; C–F, 1.335±0.01A