Laboratory of Ultrafast Spectroscopy, ISIC, and Lausanne Centre for Ultrafast Science (LACUS) , École Polytechnique Fédérale de Lausanne , CH-1015 Lausanne , Switzerland.
Department of Physics , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States.
Nano Lett. 2018 Aug 8;18(8):5007-5014. doi: 10.1021/acs.nanolett.8b01837. Epub 2018 Jul 26.
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 TiO 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.
核运动如何影响电子响应已成为材料科学中一个非常热门的话题。相干声子在超声频率下可以动态地改变光学、磁学和力学性质，在传感器和换能器方面具有广阔的应用前景。在这里，我们通过超快宽带深紫外光谱学证明，在锐钛矿 TiO 纳米颗粒中被限制的相干声子可以选择性地调制该材料所支持的二维束缚激子的振子强度。我们使用多体微扰理论计算揭示了形变势是产生观察到的相干声波包的机制。我们的研究结果提供了一种在室温下对深紫外区激子的性质进行调控和动态调节的方法。
