We explore pump-probe high harmonic generation (HHG) from monolayer hexagonal-Boron-Nitride, where a terahertz pump excites coherent optical phonons that are subsequently probed by an intense infrared pulse that drives HHG. We find, through state-of-the-art ab-initio calculations, that the structure of the emission spectrum is attenuated by the presence of coherent phonons, and is no longer comprised of discrete harmonic orders, but rather of a continuous emission in the plateau region. The HHG yield strongly oscillates as a function of the pump-probe delay, corresponding to ultrafast changes in the lattice such as bond compression or stretching. We further show that in the regime where the excited phonon period and the pulse duration are of the same order of magnitude, the HHG process becomes sensitive to the carrier-envelope-phase (CEP) of the driving field, even though the pulse duration is so long that no such sensitivity is observed in the absence of coherent phonons. The degree of CEP sensitivity vs. pump-probe delay is shown to be a highly selective measure for instantaneous structural changes in the lattice, providing a new approach for ultrafast multi-dimensional HHG-spectroscopy. Remarkably, the obtained temporal resolution for phonon dynamics is ~1 femtosecond, which is much shorter than the probe pulse duration because of the inherent sub-cycle contrast mechanism. Our work paves the way towards novel routes of probing phonons and ultrafast material structural changes and provides a mechanism for controlling the high harmonic response.
Probing exciton interaction with a spatially defined charge accumulation layer in the organic semiconductor Diindenoperylene
利用有机薄膜晶体管（OTFT）的光致发光（PL）和载流子输运测量，研究了激子和载流子之间的微观相互作用。为此目的，原型有机半导体二茚并萘嵌苯（DIP）被用作活性物质。OTFT累积层提供了空间限定的电荷和光生激子的相互作用区，导致PL强度降低高达4.5%。这种效应与累积的空穴载流子密度相关，并为非辐射激子-空穴过程的横截面提供了约1.3E-10 cm 3/s的较低估计。这是合理的，这些过程优先介导的陷阱空穴。
Probing Anharmonic and Heterogeneous Carrier Dynamics Across Sublattice Melting in a Minimal Model Superionic Conductor
The University of Osaka（大阪大学）；Nagoya University（名古屋大学）；National Institute of Advanced Industrial Science and Technology（产业技术综合研究所）；RIKEN（理化学研究所）；Institute of Integrated Research, Institute of Science Tokyo（东京科学大学综合研究机构）
Operando Raman probing of mode selective electron phonon coupling in two dimensional halide perovskites
Institut national de la recherche scientifique（国家科学研究学院）；Eindhoven University of Technology（埃因霍温理工大学）；CNR NANOTEC, c/o Department of Chemistry, University of Bari（巴里大学化学系附属意大利国家研究委员会纳米技术研究所）；Faculty of Science and Technology and MESA+ Institute for Nanotechnology, University of Twente（特温特大学科学与技术学院及MESA+纳米技术研究所）
Probing Topological Surface States and Conduction via Extended Defects in (Bi$_{1-x}$Sb$_x$)$_2$Te$_3$ Films
University of Michigan（密歇根大学）；University of Illinois（伊利诺伊大学）；Kirklareli University（克尔克拉雷利大学）；Penn State University（宾夕法尼亚州立大学）；Istanbul Technical University（伊斯坦布尔理工大学）
