Structure and Kinetics of Electron Beam Damage in a Chemisorbed Monolayer: PF3 on Ru(0001)

Effects of electron irradiation on structure and bonding of SF6 on Ru(0001)

“…It is most interesting that these fragments tend to be ordered on the surface (we observe a hexagon instead of a «halo»), in a manner very similar to the results obtained during irradiation-induced decomposition of PF 3 molecules adsorbed on Ru(0001) [27,28]. Based upon theoretical equilibrium structures of SF x (x = 1-6) [29] and simple bonding symmetry considerations similar to those for domains of PF 2 [12], it is possible that the hexagon originates, for example, from 3 domains of SF 4 species, or bridge-bonded SF 2 species, azimuthally rotated by 120°as shown in Fig. 7.…”

“…Electron stimulated desorption ion angular distribution (ESDIAD) is a very useful technique for determining the bonding structure of molecules adsorbed on single-crystal surfaces [11], since the trajectory of the desorbing particle is determined mainly by the orientation of the bond that is broken. ESDIAD also has a great utility for providing insights into structure and dynamics of decomposition of adsorbed molecules under electron bombardment [12]: distinct electron-induced changes in the ESDIAD patterns and intensities of specific ions can be monitored and analyzed. In this paper we concentrate on both F + and F -ions produced by ESD of a fractional SF 6 layer (0.25 ML) adsorbed on a Ru(0001) substrate (because of the high electron affinity of the F atom, we expect a strong F -signal in ESD).…”

Low-Energy Electron-Induced Decomposition and Reactions of Adsorbed Tetrakis(trifluorophosphine)platinum [Pt(PF3)4]

“…Collectively, these results point toward a loss of fluorine atoms from the remaining PF 3 ligands. Indeed, previous electron-stimulated desorption (ESD) studies have shown that electron irradiation of PF 3 adsorbed onto various metal surfaces yields both F + and F – species. − As a consequence of this electron-activated fluorine stripping, coordinatively unsaturated phosphorus atoms are created within the adlayer that then react with residual water vapor in the UHV chamber, driven by the thermodynamic strength of phosphorus oxygen bonds (PO and PO bond strengths are ∼550 and 350 kJ mol –1 , respectively). This assertion is supported by the observation that oxygen uptake into the film (shown in Figures and ) is observed only for electron doses ≳3 × 10 15 e – /cm 2 , correlated with the onset of the coordinatively unsaturated phosphorus atoms being created.…”

An Electron-Stimulated Desorption Ion Angular Distribution and Low-Energy Electron Diffraction Investigation of CF3I on Ru(001)

“…This is the first firm identification of off-normal emission from atomic F, although previous work by Madey et al suggested that such might occur on defect-rich portions of a Ru(001) crystal following exposure to NF 3 . , Also, ESD-generated F + was detected at angles both normal and 30° off-normal from F/W(100), although no attempt was made to attribute the off-normal beam to a specific surface structure . Another relevant study, concerning electron-induced defluorination of PF 3 on Ru(001), did not reveal the small hexagon.…”

“…Fluorine-containing compounds are ideal for investigation with techniques based on electron-stimulated desorption (ESD) due to the high ESD cross section of F + . , This sensitivity, coupled with the strong possibility of azimuthal ordering of CF 3 (ad) on a close-packed surface, makes CF 3 I on Ru(001) an ideal system for ESDIAD analysis. ESDIAD has been applied previously to the study of other highly-symmetric, fluorine-containing compounds adsorbed on metals, notably NF 3 on Ru(001), SF 6 on W(011) and W(111), and PF 3 on Ni(111) 14,15 and Ru(001). − We also note a recent related study of the ESDIAD behavior of CCl 4 on Ru(001) . To our knowledge, however, ESDIAD has yet to be applied to the investigation of an adsorbed fluorocarbon.…”