A geometric approach to decoding molecular structure and dynamics from photoionization of isotropic samples

Abstract

The photoionization dipole defines a molecule-specific vector field in the photoelectron momentum space. What information about this vector field is encoded in the photoelectron angular distribution obtained from a randomly oriented sample?

Ultrafast chirality: the road to efficient chiral measurements

“…As usual for photoionization observables, the propensity field k) by êB ð kÞ Bð kÞ=j Bð kÞj, we obtain 110,154 Bð kÞ Á êB ¼ j dþ k;g j 2 À j dÀ k;g j 2 ; êB One can show that the propensity field is similar to the Berry curvature in two band solids, 108,110 which is responsible for the circular photogalvanic effect in chiral solids 200 in the same way as the propensity field is responsible for PECD in gas phase chiral molecules. The geometric magnetic field introduced in ref.…”

“…Controlling the interplay of pump and probe pulses can be interpreted in terms of controlling this synchronisation. Thus, formulating standard photoionization observables in terms of the currents and fields they generate 154 may provide a helpful physical picture and a language for communicating the observations. Since standard photoionization observables are defined in momentum space, the continuum electron currents and the fields they generate should also be defined in momentum space.…”

“…Since standard photoionization observables are defined in momentum space, the continuum electron currents and the fields they generate should also be defined in momentum space. 154 Such a perspective is customary in condensed matter physics, where one analyzes the k-dependent fields generated by electrons photo-excited from a valence to a conduction band. Electron scattering on the lattice sites may lead to swirling electron trajectories.…”

“…Indeed, the isotropy of the molecular sample is the reason why these expressions do not depend on the relative orientations between molecular and setup vectors Rule 5. Enantio-sensitive observables pertinent to randomly oriented molecular ensembles can be written in the general form: 154,201 v ¼ X i; j g i M ij S j ;…”

“…A simple way to introduce tensorial observables is to consider photoionization. 125,154 Indeed, any photo-electron angular distribution W(y, f) can be decomposed in spherical harmonics as Wðy; fÞ ¼ X l;m b l;m Y l;m ðy; fÞ;…”