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CATEGORIES:Physics and Chemistry of Solids Group
SUMMARY:Dynamics of carbon and hydrogen on Ru(001) - Peter
  Townsend\, SMF Group\, Cavendish Laboratory
DTSTART;TZID=Europe/London:20170525T160000
DTEND;TZID=Europe/London:20170525T170000
UID:TALK70958AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/70958
DESCRIPTION:Helium-3 surface spin echo spectroscopy (HeSE) is 
 an experimental method capable of measuring atomic
 -scale surface processes associated with nano- to 
 picosecond timescales. A standard application is t
 he study of adsorbed species diffusing on a period
 ic corrugated surface\, a description that applies
  to the diffusion of carbon and hydrogen on Ru(001
 )\, two recent and completely separate experiments
  on the Cambridge instrument.\n\nSurface carbon wa
 s slowly precipitated from residual carbon in the 
 Ru bulk\, a process known to result eventually in 
 epitaxial graphene. At elevated temperatures moiré
  diffraction features characteristic of graphene/R
 u(001) typically develop over the course of hours\
 ; concurrently the spin echo method reveals jump d
 iffusion of surface carbon in the nano- to picosec
 ond window.\n\nThe quantum diffusion of H/Ru(001) 
 has previously been characterised in detail with H
 eSE. A crossover from activated to tunneling-domin
 ated diffusion occurs at a surface temperature of 
 around 140K. The story continues for 2H (deuterium
 )\, in the wider context of isotope effects in qua
 ntum diffusion.
LOCATION:Mott Seminar Room\, Cavendish Laboratory
CONTACT:Stephen Walley
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