Berlin 2012 – scientific programme
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O: Fachverband Oberflächenphysik
O 34: Poster Session I (Graphene; Plasmonics and nanooptics; Coherence and coherent control in nanophotonics and plasmonics)
O 34.18: Poster
Tuesday, March 27, 2012, 18:15–21:45, Poster E
Excited electron dynamics in Au-intercalated Graphene on Ni(111) — •Carsten Winter1, Thorben Haarlammert1, Luca Bignardi2, Petra Rudolf2, and Helmut Zacharias1 — 1Physikalisches Institut, Westfälische Wilhelms-Universität Münster — 2Zernike Institute for advancd materials, University of Groningen
Theoretical calculations predict an initial ultrafast relaxation of hot electrons accompanied by a population of optical phonons, which decays on a picosecond time scale[1]. We present an experimental set-up suited to measure the lifetime of excited electrons and their relaxation dynamics in Graphene via time-resolved two-photon photoemission. The set-up utilizes an amplified Ti:sapphire laser to generate intense femtosecond pulses with high repetition rates. Through frequency conversion by High Harmonic Generation coherent radiation at 39 eV photon energy is generated and subsequently used as the probe pulse in two-photon photoemssion. The fundamental radiation of the Ti:Sa laser is used to excite the carriers.
Graphene was produced by decomposition of ethylene on a Ni(111) substrate. The Laser-Assisted Photoelectric Effect (LAPE) was utilized to determine the XUV pulse duration to 28 fs. First experiments reveal a Ni(111) nonthermal electron lifetime of less than 20 fs. Additional measurements on Au-intercalated Graphene and Graphene on SiC will be presented.
[1]T. Elsaesser et al., Phys. Rev. Lett. 66 (1991) 1757