• 文献标题:   Ultrafast low-energy electron diffraction in transmission resolves polymer/graphene superstructure dynamics
  • 文献类型:   Article
  • 作  者:   GULDE M, SCHWEDA S, STORECK G, MAITI M, YU HK, WODTKE AM, SCHAFER S, ROPERS C
  • 作者关键词:  
  • 出版物名称:   SCIENCE
  • ISSN:   0036-8075 EI 1095-9203
  • 通讯作者地址:   Univ Gottingen
  • 被引频次:   109
  • DOI:   10.1126/science.1250658
  • 出版年:   2014

▎ 摘  要

Two-dimensional systems such as surfaces and molecular monolayers exhibit a multitude of intriguing phases and complex transitions. Ultrafast structural probing of such systems offers direct time-domain information on internal interactions and couplings to a substrate or bulk support. We have developed ultrafast low-energy electron diffraction and investigate in transmission the structural relaxation in a polymer/graphene bilayer system excited out of equilibrium. The laser-pump/electron-probe scheme resolves the ultrafast melting of a polymer superstructure consisting of folded-chain crystals registered to a free-standing graphene substrate. We extract the time scales of energy transfer across the bilayer interface, the loss of superstructure order, and the appearance of an amorphous phase with short-range correlations. The high surface sensitivity makes this experimental approach suitable for numerous problems in ultrafast surface science.