Carrier confinement and bond softening in photoexcited bismuth films
Author(s)
Shin, Taeho; Wolfson, Johanna W.; Kandyla, Maria; Teitelbaum, Samuel Welch; Nelson, Keith Adam
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Femtosecond pump-probe spectroscopy of bismuth thin films has revealed strong dependencies of reflectivity and phonon frequency on film thickness in the range of 25−40 nm. The reflectivity variations are ascribed to distinct electronic structures originating from strongly varying electronic temperatures and proximity of the film thickness to the optical penetration depth of visible light. The phonon frequency is redshifted by an amount that increases with decreasing film thickness under the same excitation fluence, indicating carrier density-dependent bond softening that increases due to suppressed diffusion of carriers away from the photoexcited region in thin films. The results have significant implications for nonthermal melting of bismuth as well as lattice heating due to inelastic electron-phonon scattering.
Date issued
2015-11Department
Massachusetts Institute of Technology. Department of ChemistryJournal
Physical Review B
Publisher
American Physical Society
Citation
Shin, Taeho, Johanna W. Wolfson, Samuel W. Teitelbaum, Maria Kandyla, and Keith A. Nelson. “Carrier Confinement and Bond Softening in Photoexcited Bismuth Films.” Physical Review B 92, no. 18 (November 2015). © 2015 American Physical Society
Version: Final published version
ISSN
1098-0121
1550-235X