Phonon-Driven Selective Modulation of Exciton Oscillator Strengths in Anatase TiO2 Nanoparticles

The way nuclear motion affects electronic responses has become a very hot topic in materials science. Coherent acoustic phonons can dynamically modify optical, magnetic, and mechanical properties at ultrasonic frequencies, with promising applications as sensors and transducers. Here, by means of ult...

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Published inNano letters Vol. 18; no. 8; pp. 5007 - 5014
Main Authors Baldini, Edoardo, Palmieri, Tania, Dominguez, Adriel, Ruello, Pascal, Rubio, Angel, Chergui, Majed
Format Journal Article
LanguageEnglish
Published United States American Chemical Society 08.08.2018
Subjects
coherent acoustic phonons
anatase TiO2
excitons
nanoparticles
Ultrafast spectroscopy
deep-ultraviolet
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Summary:The way nuclear motion affects electronic responses has become a very hot topic in materials science. Coherent acoustic phonons can dynamically modify optical, magnetic, and mechanical properties at ultrasonic frequencies, with promising applications as sensors and transducers. Here, by means of ultrafast broadband deep-ultraviolet spectroscopy, we demonstrate that coherent acoustic phonons confined in anatase TiO2 nanoparticles can selectively modulate the oscillator strength of the two-dimensional bound excitons supported by the material. We use many-body perturbation-theory calculations to reveal that the deformation potential is the mechanism behind the generation of the observed coherent acoustic wavepackets. Our results offer a route to manipulate and dynamically tune the properties of excitons in the deep-ultraviolet at room temperature.
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ISSN:1530-6984
1530-6992
DOI:10.1021/acs.nanolett.8b01837