High-resolution low-energy electron

HRLEELS plasma mass spectrometry High-resolution low-energy electron plasma-mass spectrometry (see TI-IDMS)... 

HRLEELS High-resolution low-energy electron loss spectroscopy... 

The other technique is HREELS (high resolution EELS) which utilises the inelastic scattering of low energy electrons in order to measure vibrational spectra of surface species. The use of low energy electrons ensures that it is a surface specific technique, and is often chosen for the study of most adsorbates on single crystal substrates. 

Since the technique employs low energy electrons, it is necessary to use a UHV environment. The high energy resolution in the incident electron beam is achieved by monochromatizing a thermionic electron source by means of a CHA. A second CHA is used as an energy analyser, and the basic experimental geometry is as illustrated schematically in Figure 5.47. 

As noted in the introduction, vibrations in molecules can be excited by interaction with waves and with particles. In electron energy loss spectroscopy (EELS, sometimes HREELS for high resolution EELS) a beam of monochromatic, low energy electrons falls on the surface, where it excites lattice vibrations of the substrate, molecular vibrations of adsorbed species and even electronic transitions. An energy spectrum of the scattered electrons reveals how much energy the electrons have lost to vibrations, according to the formula ... 

Figure 8.14 High-resolution electron energy loss spectroscopy (HREELS) and low-energy electron diffraction of CO adsorbed on a Rh(l 11) surface, along with structure models. The HREELS spectra show the C-O and metal-CO stretch vibrations of linear and threefold CO on rhodium (from R.Linke etal. [56]).

The past decade saw introduction of the low-energy electron microscope (LEEM) (12). It was expected potentially to be capable of moderately high resolution (6-mn) video-rate imaging of surfaces and interfaces. This would make it capable of studying dynamic processes at surfaces, thin-fibn growth, strain relief, etching, absorption. 

The experiments were performed in stainless steel UHV chambers which were equipped with the instrumentation necessary to perform Auger Electron Spectroscopy (AES), X-ray Photoelectron Spectroscopy (XPS), UV Photoelectron Spectroscopy (UPS), Low Energy Electron Diffraction (LEED), work function measurements (A( )), High Resolution Electron Energy Loss Spectroscopy (HREELS), and Temperature Programmed Desorption (TPD). The Au(lll) crystal was heated resist vely and cooled by direct contact of the crystal mounting block with a liquid nitrogen reservoir. The temperature of the Au(lll) crystal was monitored directly by means of a... 

A versatile tool to analyze vibrations of surface atoms and adsorbed molecules is high-resolution electron energy loss spectroscopy (HREELS) [359], Monoenergetic low-energy electrons (1-10 eV) are directed to the surface. Most of them are backscattered elastically. 

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