The saturation or nonlinear absorption of laser radiation by a molecular transition burns a hole in the molecular velocity distribution. Examples of hole-burning spectroscopy are described. The interaction of molecules with a standing-wave field is calculated to exhibit the inverted Lamb dip. Experimental results on I2, CH4, SF6, NH2D, and H2COare reviewed. Double resonance spectroscopy of molecules has recently been performed with laser radiations. Well-resolved signals of infrared-microwave double resonance have been observed in 14NH3 and in 15NH3 under resonant pumping with an N2O laser. A Zeeman-tuned He-Xe laser has been used to observe infrared-microwave double resonance in H2CO. Pressure dependence of double resonance in H2CO showing higher-order effects due to strong infrared and strong microwave radiations is observed and explained. Double resonance effects on the inverted Lamb dip of H2CO under microwave perturbation are also shown. Other types of nonlinear spectroscopy and their applications are briefly discussed.
Previous theories on the subject have not been able to determine clearly the appropriate combinations of anode voltage, Va, magnetic flux density, B, and anode radius, ra which will give the maximum discharge current, Imax, and the maximum pumping speeds, Smax. In the present paper, a new theory has been developed in which certain relevant paramaters are taken into account. These are the kinetic energies of electrons, radial distributions of the potential, onization probabilities, collision frequencies, sticking probabilities, sputtering yields of the cathode material and geometrical factors. Discharge currents and pumping speeds are expressed as a function of (Va/Bra) which corresponds to the electron velocities. The values of (Va/Bra) giving Imax and Smax are derived, and the appropriate combinations of Va, B and ra can be etermined from this ratio. Experimental work has also been performed, and the results show fairly good agreement with the theoretical values.
The large values of electrostrictive constant of chloroprene rubber (CR) become still larger by mixing it with carbon blacks. The values are found to be nearly proportional to, but always larger than, the square of the dielectric cnstant. The experimental results can be explained by taking into consideration the Lorentz field which acts on the dipoles of CR. When uniformity of mixture of CR and carbon black is not maintained, the effective dielectric constant of CR may vary at random as a function of the position of CR within the sample. Because electrostriction is a phenomenon which depends on the square of the electric fields, the value of the electrostrictive constant must be proportional to the sum of the mean square value and the variance of the electric field. Accordingly, an electrostrictive constant as large as 10-5 cgs esu can be obtained by a proper choice of the mixing ratio and mixing process of chloroprene and carbon blacks. The material can be given very high sensitive piezoelectric properties with the aid of a DC bias.
The frequency characteristic of particle displacement at the surface of an unpolarized piezoelectric ceramic plate due to a surface elastic wave, excited by an interdigital arrangement of electrodes, has been analyzed by an extension of Tseng's model. It has been obtained in this analysis that the transducer generates the surface waves most effectively when the wave-length is equal to the half period of the transducer, and also that the transducer can be operated at the second harmonic. In a uniformly polarized ceramic, the interdigital transducer can not excite even harmonics. The selective frequency response of a transducer is found to agree with experiment. The frequency dependences of the particle displacement at the surface on the total number of the electrode fingers in a transducer, Poisson ratio, the ratio of the piezoelectric constant e15/e33 and the ratio of electrode width to space between electrodes are also presented.
Changing the gap distance of point-plane electrodes and the pressure of the air, the authors present the region of pressure and gap distance where flash-over is proceeded by streamers. At a lower pressure, predischarge is influenced by the cathode and the discharge proceeds by quite a different mechanism.