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SUMMARY:Effect of Hydrogen Plasma Treatment on the Electronic\, Optical\, 
 Mechanical and Chemical Properties of Mo\, Rh\, Au\, HOPG and Graphene
DTSTART:20130617T103000
DTEND:20130617T113000
DTSTAMP:20260429T195320Z
UID:b65dffb024b0661a80fb9143756569983104b5635c3e8696d2f745c5
CATEGORIES:Conferences - Seminars
DESCRIPTION:Baran Eren\, Physics Department\, Univ. Basel\, CH\nWe experim
 entally investigate the properties of molybdenum/hydrogen\, rhodium/hydrog
 en\, gold/hydrogen and hydrogenated layered carbon material systems. Inves
 tigated transition metals are nanocrystalline coatings prepared by the mag
 netron sputtering method. Hydrogen introduction into initially pure metals
  or onto carbon is enabled by interactions of them with low temperature pl
 asma.\nHydrogen in transition metals may act as an electron donor or an ac
 ceptor\, changing the electronic band structure of its host. It can also r
 esult in increased number of lattice distortions\, defect sites and inelas
 tic scattering events reducing the optical transitions. Both directly impl
 y that optical properties of these metals are changed. It is shown that hy
 drogen acts as an electron acceptor in molybdenum\, but an electron donor 
 in rhodium. Both cases are investigated with various experimental techniqu
 es including photoelectron spectroscopy\, spectroscopic ellipsometry\, spe
 ctroscopic reflectometry\, spectrophotometry\, specific resistivity and di
 rect surface morphology imaging techniques. Rhodium/hydrogen system is not
  stable in air due to a catalytic reaction between hydrogen and oxygen\, w
 hereas molybdenum/hydrogen system is stable because hydrogen is strongly b
 ound to defect sites. In the case of molybdenum\, the research is extended
  to investigations on the partial delamination of the coated films and kin
 etic roughening of the surface caused by high flux hydrogen ions. Intense 
 partial buckling of the films is also observed on the gold films\, even at
  very low ion fluxes which is attributed to high compressive stress exerte
 d on the gold films as a result of hydrogen accumulation at the coating in
 terface with the substrate material. It is shown with scanning probe techn
 iques\, photoelectron spectroscopy and Raman spectroscopy that hydrogenati
 on of HOPG changes its surface corrugation\, valence band structure\, surf
 ace electron density and vibrational modes. Moreover\, it is shown that hy
 drogenation can be achieved locally and work function changes of the graph
 ene surface can be mapped with Kelvin probe force microscopy. The outcomes
  of the work are aimed to aid the fusion community in terms of material ch
 oice for the light reflecting components considered to be used in new gene
 ration reactors\, as well as the carbon community in terms of helping the 
 comprehension of properties of hydrogenated graphene.
LOCATION:CRPP\, PPB 019
STATUS:CONFIRMED
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