Control of symmetry breaking in multiphoton ionization of chiral molecules

点击翻译按钮获取中文摘要

Symmetry breaking is a recurring theme in the natural sciences with subject areas ranging from fundamental problems in particle physics to applications of chiral molecules in chemistry, biology and medicine. A particularly intriguing example of symmetry breaking in the interaction of light and matter is the Photoelectron Circular Dichroism (PECD). PECD describes a forward / backward (axial) asymmetry in the photoelectron angular distribution along the light propagation direction arising from photoionization of randomly oriented chiral molecules in the gas phase with circularly polarized light. The PECD is ideally suited to study symmetry breaking of light matter interactions associated with chirality because the observed asymmetries are many orders of magnitude more pronounced compared to the conventional circular dichroism. Recently, we have demonstrated the use of femtosecond laser sources for PECD measurements via resonance enhanced multiphoton ionization of small organic chiral molecules. With the advent of novel ultrafast light sources capable of producing few-cycle laser pulses, an additional symmetry breaking perpendicular to the light propagation direction (lateral) has become feasible by Carrier Envelope Phase (CEP) stabilization of the pulse. The main objective of this project is a demonstration of lateral symmetry breaking in the interaction of CEP-stabilized tailored intense light fields with chiral molecules. We plan to investigate the implications of CEP stabilization on the PECD and to carry out complementing parameter studies to reveal the underlying quantum dynamics. In the experiment, we will employ CEP-stabilized ultrashort pulses with tailored polarization state and a broad range of excitation wavelengths as an advanced light source for ionization and tomographic reconstruction of three-dimensional photoelectron angular distributions by velocity map imaging for detection. By combining CEP-stabilization with pulse tailoring techniques, an unprecedented degree of control on symmetry breaking in multiphoton ionization of chiral molecules will be attained.