Abstract
Strong optical irradiation of indium atomic wires on a Si(111) surface causes the nonthermal structural transition from the (8 × 2) reconstructed ground state to an excited (4 × 1) state. The immediate recovery of the system to the ground state is hindered by an energy barrier for the collective motion of the indium atoms along the reaction coordinate from the (4 × 1) to the (8 × 2) state. This metastable, supercooled state can only recover through nucleation of the ground state at defects like adsorbates or step edges. Subsequently, a recovery front propagates with constant velocity across the surface and the (8 × 2) ground state is reinstated. In a combined femtosecond electron diffraction and photoelectron emission microscopy study, we determined—based on the step morphology—a velocity of this recovery front of ∼100 m/s.
Highlights
The indium induced (4 Â 1) reconstruction on Si(111) is a prototypical atomic wire system of metal atoms on a surface and has been thoroughly investigated since it was first mentioned in 1964.1,2 During the last decade, the system has attracted attention, because the indium wires undergo a reversible phase transition from the (4 Â 1) high temperature (HT) phase to the (8 Â 2) reconstructed low temperature (LT) ground state at a critical temperature of Tc 1⁄4 120 K
The transient intensities of the (8 Â 2) and (4 Â 1) spots in the reflection high-energy electron diffraction (RHEED) diffraction pattern are analyzed to determine the relative fractions of the surface in the HT and LT phase on a femtosecond time scale
We explain this slow recovery of the LT ground state through a 1D recovery front along the indium wires starting from pre-existing seeds
Summary
The indium induced (4 Â 1) reconstruction on Si(111) is a prototypical atomic wire system of metal atoms on a surface and has been thoroughly investigated since it was first mentioned in 1964.1,2 During the last decade, the system has attracted attention, because the indium wires undergo a reversible phase transition from the (4 Â 1) high temperature (HT) phase to the (8 Â 2) reconstructed low temperature (LT) ground state at a critical temperature of Tc 1⁄4 120 K. 1(c) and 1(f) for the low energy electron diffraction (LEED) pattern and the real space structure of the outermost surface layer]. The existence of this hysteretic behavior during temperature cycling through the (8 Â 2) $ (4 Â 1) phase transition proves the first order nature of the phase transition.. The (4 Â 1) spot exhibits the opposite behavior: its intensity increases upon transition from the LT to the HT state by a factor of two upon heating and decreases again upon cooling. The transfer of intensity from the (8 Â 2) spots to the (4 Â 1) spots is observed for almost all of the (4 Â 1) spots. Such a rise of intensity on the expense of the (8 Â 2)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
