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Decelerated lattice excitation and absence of bulk phonon modes at surfaces: Ultra-fast electron diffraction from Bi(111) surface upon fs-laser excitation

Authors :
V. Tinnemann
C. Streubühr
B. Hafke
T. Witte
A. Kalus
A. Hanisch-Blicharski
M. Ligges
P. Zhou
D. von der Linde
U. Bovensiepen
M. Horn-von Hoegen
Source :
Structural Dynamics, Vol 6, Iss 6, Pp 065101-065101-5 (2019)
Publication Year :
2019
Publisher :
AIP Publishing LLC and ACA, 2019.

Abstract

Ultrafast reflection high-energy electron diffraction is employed to follow the lattice excitation of a Bi(111) surface upon irradiation with a femtosecond laser pulse. The thermal motion of the atoms is analyzed through the Debye–Waller effect. While the Bi bulk is heated on time scales of 2 to 4 ps, we observe that the excitation of vibrational motion of the surface atoms occurs much slower with a time constant of 12 ps. This transient nonequilibrium situation is attributed to the weak coupling between bulk and surface phonon modes which hampers the energy flow between the two subsystems. From the absence of a fast component in the transient diffraction intensity, it is in addition concluded that truncated bulk phonon modes are absent at the surface.

Subjects

Subjects :
Crystallography
QD901-999

Details

Language :
English
ISSN :
23297778
Volume :
6
Issue :
6
Database :
Directory of Open Access Journals
Journal :
Structural Dynamics
Publication Type :
Academic Journal
Accession number :
edsdoj.8817398fa60a494b9c0b8b6aa128cc07
Document Type :
article
Full Text :
https://doi.org/10.1063/1.5128275