Frequency factor, constancy

The value of D C - Br) in methyl bromide has been determined by the pyrolysis method by Szwarc to be 67 kcal. The strength of the C - Br bond is such that it is particularly suited to pyrolyses using the toluene carrier gas technique, and Szwarc and his collaborators have exploited this property very thoroughly. It is convenient to list here the forty-odd values of D(G - Br) in various compounds obtained in this way. Ladacki and Szwarc 28 5 give the following values for the activation energy, frequency factor and rate constant of the pyrolysis. The constancy of the frequency factor over a... 

Another major challenge in supercon magnet technology is achievement of field uniformity. It should for example be borne in mind that In order to obtain a given line width at 500 MHz requires a 5 times better field homogeneity than at 100 MHz spectrometer frequency. Realization of say 0.1 Hz proton resolution, a value which has been achieved and surpassed, therefore demands the utmost In terms of workmanship and quality of material. This concerns, among other factors, constancy of wire diameter and uniformity of winding. In spite of these precautions, such ambitious objectives necessitate various forms of field corrections, whose detailed discussion however, would break the scope of this article. 

Several factors control the form that an accumulation of sand adopts. Firstly, there is the rate at which sand is supplied secondly, there is wind speed, frequency and constancy of direction thirdly, there is the size and shape of the sand grains and fourthly, there is the nature of the surface across which the sand is moved. Sand drifts accumulate at the exits of the gaps in the landscape through which wind is channelled and are extended downwind. 

Due to the reduced Q factor of the quartz crystals in liquids, and therefore decreased phase slope, the requirements of the circuit with respect to phase (frequency dependence, noise, temperature dependence), to amplification linearity, and to temperature constancy are much higher. One electrode of the quartz crystal should be grounded to minimize parasitic effects and to allow operation of quartz arrays in conductive liquids. The increased damping of the oscillator should be overcome by automatic level control. The control variable in the amplitude control loop can be used as an independent measurement value. It also allows for calibration of/osc with respect to/s [36]. 

Treatment Schedules. With spraying, the treatment schedule stipulates spray frequency, concentration of spray solution, and constancy of climate. If the spraying is continuous, climatic factors have little influence however, they will have an effect if there are intermissions between sprayings. Thus, climate control in the surrounding atmosphere may also be considered a factor of the treatment schedule. 

The number of vibrations as well as the positions of the bands is determined by the symmetry of a molecule, the masses of the atoms making up the molecule, and the force constants of the bonds between atoms. It is thus surprising that group frequencies are found and that they retain their spectral position in a series of molecules where the symmetry and mass factors are changing. To explain the relative constancy of spectral positions of group frequencies we must examine the influence of the following four factors ... 

---