Time-resolved studies of ultrafast electronic processes in two-dimensional solids in the strongly non-thermal regime

在提议的项目中，我们的目标是研究模型型二维材料系统在强烈的亚7飞秒激光脉冲激发期间和之后不久的初级电子过程动力学，即在强非热状态下。在研究中，我们将专注于石墨材料（石墨烯和石墨）以及半导体过渡金属二硫化物MoTe2。对于这两种石墨体系，我们的目标是详细研究载流子-载流子相互作用和载流子-声子相互作用对光激发后前50秒内电子气体内部热化的影响。对于过渡金属二硫化物MoTe2，该项目将重点关注带重整效应的动力学和明显的mott跃迁，两者都与屏蔽的建立有关，因为导带被强烈的激发脉冲瞬时填充。该研究将通过专门设计的时间和角度分辨光电发射实验进行，该实验能够探测时间分辨率< 10 fs且接近傅里叶极限的超快过程。这些规范将使我们能够直接监测所涉及的电子、声子和激子自由度的特征能量尺度在与所解决问题相关的极短时间尺度上对电子结构的瞬态变化的印记。

Within the proposed project we aim for studying the dynamics of primary electronic processes in model-type two-dimensional material systems during and shortly after excitation by an intense sub-7 femtosecond laser pulse, i.e. in the strongly non-thermal regime. Within the studies we will focus on graphitic materials (graphene and graphite) as well as the semiconducting transition metal dichalcogenide MoTe2. In the case of the two graphitic systems we aim for studying in detail the impact of carrier-carrier interaction and carrier-phonon interaction onto the internal thermalization of the electron gas within the first 50 fs after optical excitation. Regarding the transition metal dichalcogenide MoTe2 the project will focus on the dynamics of band renormalization effects and a conspicuous Mott-transition, both associated with the built-up of screening as the conduction band is transiently populated by an intense excitation pulses. The studies will be conducted with a specifically designed time- and angle-resolved photoemission experiment capable of probing ultrafast processes with a time resolution < 10 fs and near the Fourier-limit. These specifications will enable us to directly monitor the imprint of the characteristic energy scales of the involved electronic, phononic and excitonic degrees of freedom onto the transient changes of the electronic structure on the extremely short timescales relevant for the addressed problems.