Desorption electron induced

Desorption of impurities adsorbed on the first wall and limiters may significantly contribute to the total impurity influx into the plasma during a discharge. In addition to thermal desorption, one must consider ion and neutral atom impact desorption, electron induced desorption and photon induced desorption. Since thermal desorption is a relatively well understood process it will not be further discussed here although it is obviously of great importance to Tokamak operation. 

In the area of electron induced desorption, information exists on some simple systems (usually pure metals) using generally monochromatic energy electrons ( 100 eV), but there are order of magnitude discrepancies between published values. The required additional data include ... 

A study that should have resolved some of these anomalies was carried out by Coburn (64), who used a quadrupole mass spectrometer to analyze the electron-induced ion desorption products from CO adsorbed on tungsten at room temperature. The 0 ions were found to be electronically desorbed, but no evidence of any CO or C + ions originating from the surface was obtained. Unfortunately, however, the ion energy distribution curve obtained for the 0 in these experiments only indicates the high energy maxima. The reasons for this may be as follows ... 

Hasselbrink E 1994 State-resolved probes of moleoular desorption dynamics induced by short-lived electronic excitations Laser Spectroscopy and Photochemistry at Metal Surfaces ed E H L Dai and W Ho (Hong Kong World Scientific) p 685... 

FIGURE 4.8. Electron-Stimulated desorption angular distribution (ESDIAD) data from PF3 adsorbed on a Ni(l 11) surface [44]. (a) Unperturbed PF3 adlayer. (b) After electron induced fragmentation into PF2 and PF species. 

Bazin, M., S. Ptasinska, A.D. Bass, L. Sanche, E. Burean and P. Swiderek. 2010. Electron induced dissociation in the condensed-phase nitromethane II. Desorption of neutral fragments. J Phys Condens Matter 22 084003. 

Ruano GD, Ferron J, Arce RD, Koropecki RR (2011) Kinetics of electron induced desorption of hydrogen in nanostmctured porous silicon. Phys Status Solidi (a) 208(6) 1453-1457 Salonen J, Laine E (1996) The quenching and recovery of photoluminescence in porous silicon. J Appl Phys 80(10) 5984-5985... 

At the same time that reduction of the nitro group occurs in NBT SAMs, cross-linking also occurs between adjacent biphenyl groups. This may be exploited to yield micro- and nanostructures. Eck et al. showed that freestanding sheets of cross-linked biphenyls may be formed by electron-induced cross-hnking and released by exposure of the samples to iodine vapor (which oxidizes the S-Au bond). Alternately, NBT SAMs may be cross-linked and the unexposed adsorbates removed by thermal desorption (thiols readily desorb from gold surfaces because the activation barrier for conversion of two thiolates to a disulfide is small). ... 

In Ref. 13 the cross section value for electron induced fluorine desorption was calculated from the time dependence of the fluorine... 

D. H. Buckley We don t really know whether the polymer bonds directly to the metal on contact via the carbon atom of dissociates first. A metal to fluorine interaction appears unlikely because the bond should be more stable than the carbon to metal bond once formed. The fluorine would not be subject to electron induced desorption prior to desorption of the carbon. 

Bald, I., Dabkowska, I., 8c Illenberger, E. (2008). Probing biomolecules by laser-induced acoustic desorption Electrons at near zero electron volts trigger sugar-phosphate cleavage. Angewandte Chemie International Edition, 47, 8518. 

DIET Desorption induced by electronic transitions [147a] General class of desorption and reaction phenomena induced by electron or photon bombardment Same as ESD and PSD... 

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