Electron spectrometer retarding field

The apparatuses used for the studies of both ammonia synthesis emd hydrodesulfurization were almost identical, consisting of a UHV chamber pumped by both ion and oil diffusion pumps to base pressures of 1 x10 " Torr. Each chamber was equipped with Low Energy Electron Diffraction optics used to determine the orientation of the surfaces and to ascertain that the surfaces were indeed well-ordered. The LEED optics doubled as retarding field analyzers used for Auger Electron Spectroscopy. In addition, each chamber was equipped with a UTI 100C quadrupole mass spectrometer used for analysis of background gases and for Thermal Desorption Spectroscopy studies. 

The energy of the primary electron beam was 2.5 keV and the energy of the Ar+ used in the depth profiles was 2 keV. The relative sensitivity factors were determined using pure standard samples and are presented in Table 14.1. Some samples were studied using an Auger spectrometer equipped with a retarding field analyser. The thickness of the films was... 

Fig. 9.8. Study of ATI peaks in Xe by photoelectron spectroscopy, obtained using the terawatt CPA system described in section 9.22. The peaks shown here are of higher order than in the previous figure, being recorded at somewhat higher laser field strength. Their kinetic energy is plotted as a function of the retarding potential of the electron spectrometer (after J.-P. Connerade et al [482]).

Fig. 7. Energy analysis by the retarding potential technique of argon primary ions produced in a standard mass-spectrometer ion source operated with a dc repeller field. The shape of the curve should be independent of the ion exit energy E data shown for three different values of E demonstrate this in the appropriately normalized plot. The distribution of experimental ion exit energies results from the finite thickness of the electron beam, and the figure shows theoretical distributions predicted for various assumed thicknesses of the electron beam. Fair agreement is found for an assumed thickness of 0.5 mm, the actual dimension of the slit through which the electron beam enters the source.

Br, Br, I, As, etc.), but the former possibility has been very little explored until now. Instrumental difficulties, namely poor versatility of NQR spectrometers and practical non availability of commercial apparatus have probably retarded the diffusion of NQR technique in the field of coordination chemistry, but vistas are now quite encouraging e.g. unpaired electron spins do not prevent detection of NQR lines, and M(3ssbauer effect measurements can be complementary to NQR specttoscopy for nuclei which are quadrupolar only in excited states. 

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