The microwave spectrum of the ethylene–HF complex in the ground vibrational state has been assigned using a Fourier transform microwave spectrometer, employing a Fabry–Perot cavity and a pulsed supersonic nozzle as a molecular source. Ethylene–HF is nonplanar, with the axis of the HF subunit oriented perpendicular to the plane of the ethylene molecule, and bisecting the carbon–carbon double bond. A hydrogen bond is formed between the HF proton and the π-electron density of ethylene. The spectroscopic constants of ethylene–HF and ethylene–DF are:
A detailed report is presented of experiments made with removable nozzle extensions to determine the relative amount of erosion when various types of steel are teemed through (I) regular fire-clay nozzles fired to different temperatures and ( 2 ) nozzles of the more refractory types. The mechanism of erosion is discussed. The data indicate the limitation of refractory materials having a P.C.E. of 28 or higher for use in nozzles or as open-hearth ladle brick.
Four isotopic species of a hydrogen-bonded dimer formed between cyclopropane and HF have been observed through assignment of their rotational spectra using a pulsed, Fourier-transform microwave spectrometer in which a gas mixture is pulsed into an evacuated Fabry–Perot cavity. The geometry of the dimer has unambiguously been shown to have HF perpendicular to the cyclopropane edge and in the plane of the ring. HF, on average, lies on the C2 symmetry axis of the dimer which is additionally the a principal axis. Hyperfine structure due to the spin–spin interaction in HF and DF was resolved as well as the hyperfine structure due to the nuclear quadrupole moment of deuterium in the cyclopropane–DF species. The following spectroscopic constants have been obtained for the cyclopropane–HF species: The rotational constants are A = 19 948(60), B = 2753.706(2), and C = 2539.115(2) MHz, the HF spin–spin constant is 121(43) kHz, and the centrifugal distortion constants are DJ = 5.08(27) and DJK = 43.5(36) kHz.
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