Damage electron beam

It was observed that the electron beam used in AES caused 

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Figure Al.7.13. ESDIAD patterns showing the angular distributions of F emitted from PF adsorbed on Ru (0001) under electron bombardment, (a) 0.25 ML coverage, (b) the same surface following electron beam damage.

Madey T E ef a/1993 Structure and kinetics of electron beam damage in a chemisorbed monolayer PFjOn Ru(OOOI) Desorption Induced by Electronic Transitions DIET V vol 31, ed A R Burns, E B Stechel and D R Jennison (Berlin Springer)... 

All elements, but not element specific No, except in special cases of electron-beam damage 4-20 A... 

AES is a useful element-specific technique for quantitative determination of the elemental composition of a surface. Although some chemical information is available in principle, the technique is used largely for elemental analysis. Electron beam damage can decompose organic adsorbates and cause damage, particularly on insulating surfaces. In some cases, the beam can reduce metal oxides. 

The saturated hydrocarbons are very susceptible to electron beam damage, both in the monolayer and multilayer forms. While aromatic hydrocarbons and other conjugated systems exhibit minimal or no beam damage effects during the time necessary to carry out the LEED experiments, the ordered structures of paraffins disappear after 5 sec of electron beam exposure as a result of desorption or partial dissociation of the organic adsorbates. 

Ordered multilayer deposits were grown on both the Cu(l 11) and Cu(lOO) substrates. Electron beam damage to the phthalocyanine molecules was not observed. Space-charge effects due to electron bombardment were not apparent below an incident electron energy of 25 eV. 

Electron beam damage effects followed the general rule that molecular groups in intimate contact with the metal substrate and aromatic groups appear relatively stable. Thus in the monolayer, alanine, with a methyl group likely sticking out from the surface, was the only molecule found to be unstable. In multilayer films, only tryptophan with the aromatic indole group to stabilize the molecule was found to yield multilayers stable under electron beam irradiation. 

Inelastic electron tunneling spectroscopy has been shown to be a useful method for the study of chemisorption and catalysis on model oxide and supported metal catalyst systems. There are in addition a number of proven and potential applications in the fields of lubrication, adhesion (48), electron beam damage (49,50), and electrochemistry for the experimentalist who appreciates the advantages and limitations of the technique. 

Better spatial definition can be attained using transmission microscopy but the opaqueness of the electrode support negates its effectiveness. The spatial distribution of elements on the surface can be resolved with a scanning Auger microprobe. The problem of electron beam damage to the modified surface has prevented widespread usage. 

Although SEMs or ESEMs are very powerful in imaging nanoscale materials or particles, caution should be taken to avoid electron beam damage to specimen. This is particularly important when a nanomanipulation system with a force measurement device is to be used to characterise the mechanical properties of particles. Ren et al. (2007, 2008) identified that such damage depended on the electron dose and exposure time, as well as the type of materials under test, and it is extremely important to find a time window in which the damage is negligible to obtain reliable mechanical property data. 

The low degree of hard-segment crystallinity in the solvent-cast samples with the added problem of loss of crystallinity from electron-beam damage prevented visualization of either the hard- or soft-segment domains by dark-field microscopy. Therefore bright-field defocus electron microscopy was used to enhance contrast between the microphases (27, 28). Only for the 1/5/4 and 1/6/5 samples was a distinct domain... 

Figure 1. Electron beam damage to ZSM-5 after a brief exposure to the focused electron beam. Crystal orientation is probably such that [010] zone axis is parallel to the optical axis of the microscope.

A reliable LEED structure determination requires a large data base, usually a number of different I-V curves collected at more than one angle of incidence. Electron beam damage to the surface must be prevented during data acquisition. 

Figure 7--Second phase particles (lattice fringes) in molecular sieve matrix, FeZSM-5, after 4h steam treatment at 700 °C, SiO0/Fe2O3-ratio 90. Molecular sieve structure is amorphous due to electron beam damage.

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