Beam deflection electric

Other measurements. Induced dipole moments can be measured by most of the familiar methods that are designed to measure permanent dipole moments. We mention in particular the beam deflection method by electric fields, using van der Waals molecules, and molecular beam electric resonance spectroscopy of van der Waals molecules [373, 193, 98]. 

Fig. 6.5. (a) Angular momentum orientation via beam deflection in a magnetic field. (6) Figure axis orientation for symmetric top molecules via beam deflection in an electric field, (c) Figure axis orientation in hexapole focussing field. 

The essential elements.of the experiment are a) an effusive molecular beam source, b) inhomogeneous deflecting electric polefaces, c) surface ionization detector, capable of translation in order to obtain the deflected beam pattern. 1, 2, are the distance from the source to the front of the polefaces, the length of the polefaces and the distance from the back of the polefaces to the detector, respectively. A general review of deflection methods for determining polarizabilities is given by Miller and Bederson (8). 

The parameters that are measured run a wide gamut from the routine (current, potential or some electrical parameter) to the exotic (e.g., beam deflection due to refractive index changes). A hierarchical approach to discussing these variant methods has been described [52]. Thus, the methods in Table 2 fall under the categories of purely electrical (entries 1-3, 8 and 9), purely optical (entry titled photoluminescence spectroscopy and entries 12 and 13), electro-optic (electroluminescence spectroscopy) or opto-electric (entries 4-7). We can also distinguish between frequency-resolved (entries 3-7) and time-resolved (entries 10 and 14) measurements, although it must be noted that in many instances (e.g., entries 8 and 11) both steady-state and time-resolved approaches are feasible. 

Metallurgy-metals provide an ideal specimen for microbeam analysis, their high thermal conductivity minimizes thermal damage and their high electrical conductivity removes any possibility of specimen charging giving rise to a beam deflection. 

FIG. 20. Cathode ray tube enabled Thomson to measure deflection of electron beams in electric fields of known strength. Beam passed between the plates, whose field deflected electrons, shifting their striking points along the scale. 

The particle size dependence of thermophoresis has been extensively studied for dilute polystyrene beads dispersed in aqueous solutions with very thin electric double layers under pH conditions of 7 8. The results of these investigations however are controversial and inconclusive. As shown in Fig. 6, Duhr and Braun [2] reported that the thermal diffusion coefficient Dj is proportional to particle diameter at room temperature by using the fluorescence detection method. Although Braibanti et al. [10] observed a similar dependence of Dj on particle size at a temperature of 45 °C through the beam deflection method, they found independence of with particle size at room temperature and at 5 °C, as shown in Fig. 6. In addition, for concentrated polystyrene beads at a temperature of 50 °C, Dj is not found to be dependent on particle size. 

Signs of electric dipole moments, which must be obtained by techniques other than Stark effect measurements, are listed in the column Varia, remarks . There exist some molecular beam deflection data of electric dipole moments which have reached the accuracy of dipole moments determined by microwave spectroscopy or may even be better. These values have been included in columns 3-"6. If there are experimental dipole moments from other spectroscopic regions they are listed too. The methods are given with abbreviations as explained in part 1. 

UV-visible absorption/reflection Electron spin resonance Raman spectroscopy Fourier transform infrared spectroscopy Probe beam deflection Scanning tunneling microscopy Scanning electrochemical microscopy Work function measurements In situ electrical conductivity 144, 277, 373-382 247, 369. 375,. 383, 384 144, 385-389 390, 391 156, 392, 393. 394, 395 3%, 397 172, 173 256, 289, 290, 398-401... 

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