Electron asymmetries in the photoionization of chiral molecules: possible astrophysical implications

Hadidi, Rim; Božanić, Dušan K.; Garcia, Gustavo A.; Nahon, Laurent

doi:10.1080/23746149.2018.1477530

Cited by 37 publications

(58 citation statements)

References 149 publications

(207 reference statements)

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“…Measuring PECD has been boosted by techniques capturing the full photoelectron momentum distribution such as velocity map imaging (VMI) or a recently developed stereo‐electron detector . Recently, single‐photon PECD highlighting in addition the relevance for astrophysical research has been reviewed.…”

Section: Figurementioning

confidence: 99%

Observation of Photoelectron Circular Dichroism Using a Nanosecond Laser

et al. 2019

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Photoelectron circular dichroism (PECD) is a fascinating phenomenon both from a fundamental science aspect but also due to its emerging role as a highly sensitive analytic tool for chiral recognition in the gas phase. PECD has been studied with single‐photon as well as multi‐photon ionization. The latter has been investigated in the short pulse limit with femtosecond laser pulses, where ionization can be thought of as an instantaneous process. In this contribution, we demonstrate that multi‐photon PECD still can be observed when using an ultra‐violet nanosecond pulse to ionize chiral showcase fenchone molecules. Compared to femtosecond ionization, the magnitude of PECD is similar, but the lifetime of intermediate molecular states imprints itself in the photoelectron spectra. Being able to use an industrial nanosecond laser to investigate PECD furthermore reduces the technical requirements to apply PECD in analytical chemistry.

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Section: Figurementioning

confidence: 99%

Observation of Photoelectron Circular Dichroism Using a Nanosecond Laser

et al. 2019

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“…Besides, PECD has been shown to be very sensitive to static molecular structures, such as conformers, isomers, clusters, chemical substitution and to dynamic molecular motions such as vibrations (for reviews see Ref. 28,29 ).…”

Section: Introductionmentioning

confidence: 99%

Conformer-Dependent VUV Photodynamics and Chiral Asymmetries in Pure Enantiomers of Gas Phase Proline

Hadidi¹,

Božanić²,

Ganjitabar³

et al. 2020

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Proline is a unique amino-acid, with a secondary amine fixed within a pyrrolidine ring providing specific structural properties to proline-rich biopolymers. Gas-phase proline possesses four main H-bond stabilized conformers differing by the ring puckering and carboxylic acid orientation. The latter defines two classes of conformation, whose large ionization energy difference allows a unique conformer-class tagging via electron spectroscopy. Photoelectron circular dichroism (PECD) is an intense chiroptical effect sensitive to molecular structures, hence theorized to be highly conformation-dependent. Here, besides a conformer-dependant cation fragmentation behaviour, we present experimental evidence of an intense and striking conformer-specific PECD, measured in the VUV photoionization of proline. This finding, combined with theoretical modelling, allows a refinement of the conformational landscape and energetic ordering, that proves inaccessible to current molecular electronic structure calculations. Additionally, astrochemical implications regarding a possible link of PECD to the origin of life’s homochirality are considered in terms of plausible temperature constraints.

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“…This was much slower than for the VMI measurements of the monoterpene ketones shown in Figure 1 due to a much less powerful ionization laser and lower target densities. However, by using a more powerful laser, increasing the evaporation rate of the sample, using an aerodynamic lens source coupled to a thermodesorber, 21 and running the detectors in analogue mode, the analysis speeds achieved with the VMI could be replicated.…”

Section: Pharmaceutically Interesting Moleculesmentioning

confidence: 99%

Using photoelectron elliptical dichroism (PEELD) to determine real‐time variation of enantiomeric excess

et al. 2020

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In this work, the photoionization of chiral molecules by an elliptically polarized, high repetition rate, femtosecond laser is probed. The resulting 3D photoelectron angular distribution shows a strong forward–backward asymmetry, which is highly dependent not only on the molecular structure but also on the ellipticity of the laser pulse. By continuously varying the laser ellipticity, we can observe molecular and enantiomer changes in real time at a previously unseen speed and precision. The technique allows enantiomeric excess of a pure compound to be measured with a 5% precision within 3 s, and a 10‐min acquisition yields a precision of 0.4%. The isomers camphor and fenchone can be easily distinguished, unlike with conventional mass spectrometry. Preliminary results for the pharmaceutically interesting ibuprofen are also given, showing the capability of photoionization as a means of distinguishing larger molecular systems.

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Electron asymmetries in the photoionization of chiral molecules: possible astrophysical implications

Cited by 37 publications

References 149 publications

Observation of Photoelectron Circular Dichroism Using a Nanosecond Laser

Observation of Photoelectron Circular Dichroism Using a Nanosecond Laser

Conformer-Dependent VUV Photodynamics and Chiral Asymmetries in Pure Enantiomers of Gas Phase Proline

Using photoelectron elliptical dichroism (PEELD) to determine real‐time variation of enantiomeric excess

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