Chiral Asymmetry in the Multiphoton Ionization of Methyloxirane Using Femtosecond Electron–Ion Coincidence Imaging

Abstract

Multiphoton photoelectron circular dichroism (MP-PECD) has been observed as an asymmetry in the angular distribution of photoelectrons emitted in the ionization of pure enantiomers of the small chiral molecule methyloxirane using a femtosecond laser operated at 420 nm. Energetically, this requires the uptake of four photons. By switching the laser between left- and right-circular polarization, and observing the differences in the full three-dimensional electron momentum distribution recorded in an electron-ion coincidence technique, the chiral (odd) terms in the angular distribution expression can be isolated. Electron events can additionally be filtered by coincident ion mass, providing mass-tagged electron distributions and quantitative measures of the MP-PECD asymmetry that help characterize the different ionization channels. For the production of ground state parent cation, the magnitude of the mean chiral asymmetry is measured to be 4.7%, with a peak magnitude exceeding 10%

Experimental and Theoretical Investigation of the 3sp(d) Rydberg States of Fenchone by Polarized Laser Resonance‐Enhanced‐Multiphoton‐Ionization and Fourier Transform VUV Absorption Spectroscopy

“…Some further measurements were made with a 3 kHz, 150 fs pulse duration laser coupled with a dual imaging electron‐ion coincidence spectrometer, again as previously described [41–43] …”

Link between Photoelectron Circular Dichroism and Fragmentation Channel in Strong Field Ionization

“…One of them is in the single photon ionization regime showing a rich dependency on the fragmentation channel. The other two , are in the (resonant) multiphoton regime revealing no dependency on the fragmentation channel. Here we expand these studies to the strong field regime.…”

Universality of photoelectron circular dichroism in the photoionization of chiral molecules

“…Lux et al [9] measured a ∼15% PECD in (2+1) resonance-enhanced multiphoton ionization (REMPI) of fenchone and camphor where two photon absorption brings the molecule into an electronic excited state while the third photon ionizes the system. Since this pioneering experiment, REMPI-PECD has been measured in other compounds, in (2+1) [10][11][12] and (3+1) [13] configurations. Recently, Lux et al observed PECD in the first above threshold ionization (ATI) peak in a (2+2) scheme [14].…”