Tracking the surface atomic motion in a coherent phonon oscillation

Article

关键词: MONOCHROMATOR BEAMLINE;    PHOTOEMISSION;    SPECTROSCOPY;   

DOI  :  10.1103/PhysRevB.106.L201409

来源: SCIE

【 摘 要 】

X-ray photoelectron diffraction is a powerful tool for determining the structure of clean and adsorbate-covered surfaces. Extending the technique into the ultrafast time domain will open the door to studies as diverse as the direct determination of the electron-phonon coupling strength in solids and the mapping of atomic motion in surface chemical reactions. Here we demonstrate time-resolved photoelectron diffraction using ultrashort soft x-ray pulses from the free electron laser FLASH. We collect Se 3d photoelectron diffraction patterns over a wide angular range from optically excited Bi2Se3 with a time resolution of 140 fs. Combining these with multiple scattering simulations allows us to track the motion of near-surface atoms within the first 3 ps after triggering a coherent vibration of the A(1g) optical phonons. Using a fluence of 4.2 mJ/cm(2) from a 1.55 eV pump laser, we find the resulting coherent vibrational amplitude in the first two interlayer spacings to be on the order of 0.01 angstrom.

【 授权许可】

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