Pulsed electric fields performance

Heiger, D. N., Cohen, A. S., Aharon, S., and Karger, B. L., Separation of DNA restriction fragments by high performance capillary electrophoresis with low and zero cross-linked polyacrylamide using continuous and pulsed electric fields,. Chromatogr., 516, 33, 1990. 

Cooling has also been achieved for molecules without laser techniques, but employing interaction with cold helium gas or by using a pulsed electric field [9.453]. Clearly, many fundamental studies can be performed on well-prepared samples of cooled molecules. 

There exist a number of laser-induced techniques for ionizing these neutrals, such as resonance-enhanced multiphoton ionization (in ion source I or II, Figures lA and IB), laser-induced vacuum UV ionization (e.g. by 118 nm from a 3x355 nm/ Nd YAG laser), electron attachment (in ion source I) and electron ionization (in ion source II). Electrons may be supplied by laser-induced photoelectron emission from metal surfaces, preferably from thin wires made out of material having a low work function (e.g. hafnium). Ions formed in source I have to drift into the ion optics of the mass spectrometer (together with the neutral molecular beam) and can be extracted by a pulsed electric field while ionization in source II may be performed within a static electric field with instantaneous ion extraction. 

If the coherent vibration of these dipoles is essential, the pulsing electric field is expected to be much more effective than the direct current electric field (DC field), as long as the coherent frequency components are contained. Therefore, the present study has been performed mainly with a pulsing electric field. 

Thus, if measurements are performed on specimens of differing thicknesses, at identical applied fields, then variations in the relative degree of dispersion should be observed, with thicker specimens being characterized by less dispersive transit pulses (Fig. 3.2). It is interesting to note that a number of analysis (see Ref [8]) have assumed that an increase in electric field in a given specimen will result in an increase in relative dispersion (due to a reduction of the mean transit time). However,... 

So we see that spectral broadening of the comb [29,30] is achieved by imposing a large frequency chirp on each of the pulses. Provided that the coupling efficiency into the fiber is stable, the periodicity of the pulse train is maintained. The discussion of section 3 is thus equally valid if the electric field E(t) as measured for example at the fiber output facet instead of the laser output coupler. As described below we have used a frequency comb widened to more than 45 THz by a conventional single mode fiber to perform the first phase coherent vacuum UV to radio frequency comparison in our Garching laboratory [16,31], In recent experiments we have confirmed that the fiber does not affect the mode spacing constancy within our experimental uncertainty of a few parts in 1018 [13]. 

The preparation of the Rydberg circular states Is performed by pulsed laser excitation followed by an adiabatic microwave transfer method (A.M.T. M.) already described in ref. [a]. This method requires that the atom interacts with an homogeneous electric field Fj., produced by the stack of equally spaced metallic plates shown on Fig. 1-a. This field removes the degeneracy of the various n-manifolds. 

Most of hydrodynamic methods have focused on increasing the particle back transport from the membrane-liquid interface by increasing the shear rate and the flow instability in the boundary layer. These techniques include secondary flows, spacers and inserts, pulsed flow, high shear rate devices, vibrations, and two-phase flow. The physical methods that are currently been tested to enhance filtration performance of membranes include the application of electric fields and ultrasound. 

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