Photoelectron Circular Dichroism

Powis, Ivan

doi:10.1002/9781118120187.ch15

Cited by 8 publications

(6 citation statements)

References 51 publications

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“…Section 4.2.1.1), we investigated asymmetries in the PMD from MPI of the chiral fenchone molecule using CEP-stable few-cycle pulses. The manipulation of lateral asymmetries in chiral molecules is particularly interesting because these molecules also exhibit a pronounced axial, i.e., forward/backward asymmetry in the photoelectron emission due to the PECD [208]. Recent measurements of the PECD of (-)-fenchone molecules from MPI with circularly polarized 400 nm pulses, depicted in Figure 11A, reproduce our previous results [97,150].…”

Section: Asymmetries In the Photoemission From Chiral Moleculessupporting

confidence: 78%

Multichromatic Polarization-Controlled Pulse Sequences for Coherent Control of Multiphoton Ionization

et al. 2021

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In this review, we report on recent progress in the generation and application of multichromatic polarization-tailored pulse sequences for the coherent control of multiphoton ionization (MPI) dynamics and present unpublished experimental results that complement our previous findings. Specifically, we utilize single-color, bichromatic, and trichromatic polarization-controlled pulse sequences generated by spectral amplitude, phase and polarization modulation of a carrier-envelope phase (CEP)-stable white light supercontinuum for MPI. The analysis of the number of ionization pathways and the number of distinct final free electron states shows that both increase significantly, but scale differently with the number of absorbed photons and the number of pulses in the sequence. In our experiments, ultrafast polarization shaping is combined with high-resolution photoelectron tomography to generate, control, and reconstruct three-dimensional photoelectron momentum distributions from atomic and molecular MPI. We discuss the use of polarization-controlled single-color and bichromatic pulse sequences in perturbative and non-perturbative coherent control of coupled electron-nuclear dynamics in molecules, atomic spin-orbit wave packet dynamics and the directional photoemission from atoms and chiral molecules. We compare the coherent control of CEP-insensitive intraband multipath interference in the MPI with a fixed number of photons with CEP-sensitive interband multipath interference in the ionization with a different number of photons. The generation and control of free electron vortices with even-numbered rotational symmetry by MPI with single-color pulse sequences is contrasted with the bichromatic control of CEP-sensitive electron vortices with odd-numbered rotational symmetry. To illustrate the potential of multichromatic pulse sequences for coherent control, we present a trichromatic scheme for shaper-based quantum state holography.

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Section: Asymmetries In the Photoemission From Chiral Moleculessupporting

confidence: 78%

Multichromatic Polarization-Controlled Pulse Sequences for Coherent Control of Multiphoton Ionization

et al. 2021

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“…8,9 These asymmetries fall in the range of one to a few tens of a percent and so are at least 3 orders of magnitude greater than more typical circular dichroism in absorption spectroscopies. This inherent sensitivity, combined with the in-built experimental efficiency of charged particle detection, make PECD an ideal method to probe isolated chiral molecules in the gas phase, which can even be extended to observe minor cluster components generated in a supersonic molecular beam.…”

Section: ■ Introductionmentioning

confidence: 97%

“…Photoelectron circular dichroism (PECD) is an addition to the rank of chiroptical methods that measures a forward–backward asymmetry in the angular distribution of photoelectrons emitted upon ionization by a beam of circularly polarized radiation. , These asymmetries fall in the range of one to a few tens of a percent and so are at least 3 orders of magnitude greater than more typical circular dichroism in absorption spectroscopies. This inherent sensitivity, combined with the in-built experimental efficiency of charged particle detection, make PECD an ideal method to probe isolated chiral molecules in the gas phase, which can even be extended to observe minor cluster components generated in a supersonic molecular beam .…”

Section: Introductionmentioning

confidence: 99%

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

2014

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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%

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“…17 For an extended overview of the present status of PECD experiments with synchrotron radiation we like to refer to the recent reviews. [18][19][20] Because the angular scattering distribution of photoelectrons ejected from a chiral molecule is very sensitive to the chiral nature of the excitation and dynamics, we proposed to combine photoelectron-photoion coincidence imaging with femtosecond multiphoton ionization in a so-called Reaction Microscope to detect enantiomers with mass-selectivity and high sensitivity. 21 In this way, using femtosecond multiphoton excitation, the photoelectron circular dichroism technique could be opened up to table-top experimental laboratories.…”

Section: Introductionmentioning

confidence: 99%

Imaging photoelectron circular dichroism of chiral molecules by femtosecond multiphoton coincidence detection

Lehmann

Ram

Powis

et al. 2013

The Journal of Chemical Physics

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163

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Here, we provide a detailed account of novel experiments employing electron-ion coincidence imaging to discriminate chiral molecules. The full three-dimensional angular scattering distribution of electrons is measured after photoexcitation with either left or right circular polarized light. The experiment is performed using a simplified photoelectron-photoion coincidence imaging setup employing only a single particle imaging detector. Results are reported applying this technique to enantiomers of the chiral molecule camphor after three-photon ionization by circularly polarized femtosecond laser pulses at 400 nm and 380 nm. The electron-ion coincidence imaging provides the photoelectron spectrum of mass-selected ions that are observed in the time-of-flight mass spectra. The coincident photoelectron spectra of the parent camphor ion and the various fragment ions are the same, so it can be concluded that fragmentation of camphor happens after ionization. We discuss the forward-backward asymmetry in the photoelectron angular distribution which is expressed in Legendre polynomials with moments up to order six. Furthermore, we present a method, similar to one-photon electron circular dichroism, to quantify the strength of the chiral electron asymmetry in a single parameter. The circular dichroism in the photoelectron angular distribution of camphor is measured to be 8% at 400 nm. The electron circular dichroism using femtosecond multiphoton excitation is of opposite sign and about 60% larger than the electron dichroism observed before in near-threshold one-photon ionization with synchrotron excitation. We interpret our multiphoton ionization as being resonant at the two-photon level with the 3s and 3p Rydberg states of camphor. Theoretical calculations are presented that model the photoelectron angular distribution from a prealigned camphor molecule using density functional theory and continuum multiple scattering X alpha photoelectron scattering calculations. Qualitative agreement is observed between the experimental results and the theoretical calculations of the Legendre moments representing the angular distribution for the two enantiomers. The electron-ion coincidence technique using multiphoton ionization opens new directions in table-top analytical mass-spectrometric applications of mixtures of chiral molecules.

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Photoelectron Circular Dichroism

Cited by 8 publications

References 51 publications

Multichromatic Polarization-Controlled Pulse Sequences for Coherent Control of Multiphoton Ionization

Multichromatic Polarization-Controlled Pulse Sequences for Coherent Control of Multiphoton Ionization

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

Imaging photoelectron circular dichroism of chiral molecules by femtosecond multiphoton coincidence detection

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