The homogeneous exchange reaction between ammonia and deuterium was studied in a single-pulse shock tube over a wide range of compositions and initial pressures within the 1150–1450°K temperature range. The rate of production of HD in the early stages of the reaction, in the composition range 0.67–4% NH3 and 0.67–4% D2 in argon is given by d[HD]/dt = kb[Ar]0.38[NH3]0.61[D2]1.01, where kb = 1013.0 ± 0.3exp[−(37.2 ± 1.0) × 103/RT]cc mole−1·sec−1. The contribution of a chain mechanism to the exchange process was ruled out. A mechanism based on vibrational excitation of the deuterium molecule to a critical vibration level as a slow step prior to the atom switching step is proposed.

The spectral radiances at wavelengths 7.8 ‐ 11.5 µm of the sea surface at small angles below the horizon show a well defined minimum. The location of the minimum, its sharpness and its magnitude depend on wavelength, sea state, atmospheric turbidity, sea and air temperatures. Remote sensing of sea state appears possible by interpreting spectral radiances measured in a vertical scan of the sea near the horizon. A close proximity of the minimum to the horizon indicates a high sea state.

The homogeneous exchange reaction between tetradeutero methane and ammonia was studied behind reflected shocks in a single-pulse shock tube over the temperature range of 1300-1800°K. The rate of production of CD3H at the early stages of the reaction in mixtures ranging between 1-4.5y0 NH3 and l--4.3yO CD4 in argon is given by d]o, where ka = 8 X 10'6 exp (-65.3 X lO3/RT) cm3/mole.sec. This activation energy is considerably lower than the one that may be expected on the basis of a pure free radical mechanism. It is rationalized by CtDs impurities in the methane. No clear answer can be obtained regarding the role of a four-center intermediate in this reaction.* This work was abstracted from the dissertation of P. S., submitted to the Senate of Hebrew University in partial fulfillment of the requirements for the Ph.D. degree.