posted on 2021-03-04, 13:06authored bySebastian Hartweg, Gustavo A. Garcia, Dušan K. Božanić, Laurent Nahon
Structural
changes at the molecular level, occurring at the onset
of condensation, can be probed by angle-resolved valence photoelectron
spectroscopy, which is inherently sensitive to the electronic structure.
For larger condensed systems like aerosol particles, the observation
of intrinsic angular anisotropies in photoemission (β parameters)
is challenging due to the strong reduction of their magnitude by electron
transport effects. Here, we use a less common, more sensitive observable
in the form of the chiral asymmetry parameter to perform a comparative
study of the VUV photoelectron spectroscopy and photoelectron circular
dichroism (PECD) between pure gas phase enantiomers of the amino acid
serine and their corresponding homochiral nanoparticles. We observe
a relatively large (1%) and strongly kinetic energy-dependent asymmetry,
discussed in terms of the emergence of local order and conformational
changes potentially counterbalancing the loss of angular information
due to electron transport scattering. This demonstrates the potential
of PECD as a sensitive probe of the condensation effects from the
gas phase to bulk-like chiral aerosol particles surpassing the potential
of conventional photoemission observables such as β parameters.