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

Baldini E; Palmieri T; Dominguez A; Ruello P; Rubio A; Chergui M

doi:10.1021/acs.nanolett.8b01837

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

Baldini E Laboratory of Ultrafast Spectroscopy, ISIC, and Lausanne Centre for Ultrafast Science (LACUS) , École Polytechnique Fédérale de Lausanne , CH-1015 Lausanne , Switzerland.
Palmieri T Laboratory of Ultrafast Spectroscopy, ISIC, and Lausanne Centre for Ultrafast Science (LACUS) , École Polytechnique Fédérale de Lausanne , CH-1015 Lausanne , Switzerland.
Dominguez A Departamen to Fisicade Materiales , Universidad del País Vasco , Avenue Tolosa 72 , E-20018 , San Sebastian , Spain.
Ruello P Institut des Molécules et Matériaux du Mans, UMR CNRS 6283 , Le Mans Université , 72085 Le Mans , France.
Rubio A Departamen to Fisicade Materiales , Universidad del País Vasco , Avenue Tolosa 72 , E-20018 , San Sebastian , Spain.
Chergui M Laboratory of Ultrafast Spectroscopy, ISIC, and Lausanne Centre for Ultrafast Science (LACUS) , École Polytechnique Fédérale de Lausanne , CH-1015 Lausanne , Switzerland.

2018-07-25

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Nano letters. - 2018

English 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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