Within a bottom/up approach of molecular complexity, the study of isolated, substrate- and solvent-free chiral species is crucial, but classical chiroptical probes such as Circular Dichroism (CD) in absorption are poorly adapted to dilute matter because of their very weak associated asymmetries.
At the opposite, two decades ago was introduced a new chiroptical effect called Photoelectron...
PhotoElectron Circular Dichroism (PECD) is an effect driven by electric dipole interactions between an ensemble of chiral molecules and ionizing circularly polarized light [1,2]. It results in a preferential emission direction of photoelectrons along the light propagation axis, leading to an asymmetry that can be observed by recording their angular distribution with an electron detector....
A molecule is chiral if it lacks both a plane and a center of symmetry, resulting in two non-superimposable mirror-image forms known as enantiomers. Chirality is crucial in the physical and biological sciences because enantiomers, despite having the same chemical structure, often exhibit different chemical and physical properties when interacting with other chiral entities. While chirality is...
Photoelectron Circular Dichroism of Aqueous Solutions
Bernd Winter
Fritz-Haber-Institut, Berlin, Germany
Chirality-sensitive, large-cross section Photoelectron Circular Dichroism (PECD) — the forward-backward asymmetry in photoemission from chiral molecules photoionized by circularly polarized light — uniquely connects molecular electronic structure to chirality. In addition, core-level...
Time-resolved circular dichroism (CD) is a powerful technique to investigate the dynamics of conformational changes in molecules and in biomolecules. Starting from a pump-probe configuration, it consists in measuring the CD of the pump-excited molecules to gain information on the relevant timescales. Complementary experiments on short (picoseconds) or longer (microseconds) timescales have been...
The incorporation of chiral structures into photochemical systems is a powerful strategy to control their functions [1]. For example, uni-directional molecular motors, chiral photocatalysts, and chiral metal nanostructures have achieved exceptional levels of stereocontrol over mechanical motion, energy transfer, and electric charge-carriers on the nanoscale. However, the direct...
Since the pioneering transient circular dichroism (CD) experiments of Xie and Simon$^1$ and Kliger$^2$ more than three decades ago, laser technology has developed enormously, and highly stable, ultrashort broad-band pulses for extremely sensitive differential absorption measurements at wavelengths from the mid-IR to the far UV have become routinely available. Yet, progress in time-resolved CD...
Selective absorption of light at specific frequencies determines the color of an object and results from the discrete energy levels of atoms or molecules in the material. This selective absorption also occurs when the handedness of polarized light interacts with the non-superimposable mirror image of a chiral object, as in circular dichroism (CD). Tunability of light absorption, it is...
We present here our recent work on the development of ab initio time-domain methods for studying the contribution of inner molecular orbitals to the HHG spectrum [1] of aligned or non-aligned molecules [2-4]. First, we show how, in the presence of a linearly polarised pulse, the selection rules for harmonic generation can be different depending on the molecular orbital considered: an example...
Since the pioneering work by French scientists in the early 1800s, optical activity and chiral light-matter interactions have been produced via the chirality of light stemming from a degree of ellipticity in its local polarisation state. The mechanism is well understood: the polarisation state can rotate in a left or right-handed fashion and leads to differential interactions with left and...
This presentation will give an overview about the generation and applications of X-ray beams that exhibit an orbital angular momentum (OAM) using helical zone plates, focusing particularly on their ability to probe chiral properties in matter. Helical (or spiral) zone plates represent an advanced class of diffractive optical lenses that can modulate the phase of light while focusing it at...
The growing interest in chirality represents a notable example of convergence between different areas of research within the realm of condensed matter. The observation of skyrmions in compounds of group B20 [1] represents only the first report of a wealth of magnetic ordering [2] and collective excitations [3] that can be realized only in the absence of inversion and mirror symmetry...
