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SUMMARY:Dynamics of carbon and hydrogen on Ru(001) - Peter Townsend\, SMF 
 Group\, Cavendish Laboratory
DTSTART:20170525T150000Z
DTEND:20170525T160000Z
UID:TALK70958@talks.cam.ac.uk
CONTACT:Stephen Walley
DESCRIPTION:Helium-3 surface spin echo spectroscopy (HeSE) is an experimen
 tal method capable of measuring atomic-scale surface processes associated 
 with nano- to picosecond timescales. A standard application is the study o
 f adsorbed species diffusing on a periodic corrugated surface\, a descript
 ion 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 was slowly precipitated from residual carbon in the Ru bul
 k\, a process known to result eventually in epitaxial graphene. At elevate
 d temperatures moiré diffraction features characteristic of graphene/Ru(0
 01) typically develop over the course of hours\; concurrently the spin ech
 o method reveals jump diffusion of surface carbon in the nano- to picoseco
 nd window.\n\nThe quantum diffusion of H/Ru(001) has previously been chara
 cterised in detail with HeSE. A crossover from activated to tunneling-domi
 nated diffusion occurs at a surface temperature of around 140K. The story 
 continues for 2H (deuterium)\, in the wider context of isotope effects in 
 quantum diffusion.
LOCATION:Mott Seminar Room\, Cavendish Laboratory
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