Universality of photoelectron circular dichroism in the photoionization of chiral molecules
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| Anzahl der Teile | 51 | |
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| Lizenz | CC-Namensnennung 3.0 Unported: Sie dürfen das Werk bzw. den Inhalt zu jedem legalen Zweck nutzen, verändern und in unveränderter oder veränderter Form vervielfältigen, verbreiten und öffentlich zugänglich machen, sofern Sie den Namen des Autors/Rechteinhabers in der von ihm festgelegten Weise nennen. | |
| Identifikatoren | 10.5446/38835 (DOI) | |
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51
00:00
Chiralität <Elementarteilchenphysik>SchmelzsicherungElementarteilchenphysikVideotechnikChiralität <Elementarteilchenphysik>NeutronenaktivierungLeistungssteuerungImpaktFeldeffekttransistorBesprechung/Interview
00:28
Phase <Thermodynamik>Chiralität <Elementarteilchenphysik>
00:40
Zirkulardichroismus
00:46
StrahlungSiebdruckLeuchtstoffSpektrometerChiralität <Elementarteilchenphysik>KlangeffektSpeckle-InterferometrieVerband der Metallindustrie Baden-WürttembergResonanzenergieStrahlungPhotonikFamilie <Elementarteilchenphysik>IonHadronenjetElektrisches DipolmomentNiederspannungsnetzVakuumphysikFahrgeschwindigkeitGleichstromTrenntechnikLicht
01:25
InfrarottechnikIonisationLuftionisationSchwellenspannungMaschineLaserMonitorüberwachungIntensitätsverteilungModellbauerInstitut für RaumfahrtsystemeWeltraumKlangeffektPhotonikProzessleittechnikInfrarotlaserResonanzenergieFaraday-EffektFamilie <Elementarteilchenphysik>PhotonElektronendichteClosed Loop IdentificationElektronSchwächungPhototechnikChiralität <Elementarteilchenphysik>Lichtstreuung
02:48
Chiralität <Elementarteilchenphysik>RestkernKristallgitterNiederspannungsnetzElektronSpannungsabhängigkeitLichtstreuungComputeranimation
02:55
ElektronSpannungsabhängigkeitMechanikerinFeldquantLichtstreuungLichtstreuungSchwingungsphaseElektronSpannungsabhängigkeitLaserTrenntechnik
03:42
ElektronTrajektorie <Meteorologie>SpannungsabhängigkeitMechanikerinLichtstreuungFeldquantChiralität <Elementarteilchenphysik>TextilienKleiner LöweHomogene TurbulenzWindparkTinteUnterbrechungsfreie StromversorgungBasis <Elektrotechnik>ÜberlagerungsempfängerWellenlängeSpannungsabhängigkeitWeltraumBlatt <Papier>KommunikationssatellitLichtstreuungTrajektorie <Meteorologie>ElektronFeldquantLaserComputeranimation
Transkript: Englisch(automatisch erzeugt)
00:03
Pairs of chiral molecule have the same physical and chemical propriety unless they interact with another chiral object. Because our body is full of chiral molecule, it has huge impact on biological activities. This chiral sensitivity distinguishes from a nasal decongestant from powerful psychoactive street drugs.
00:28
Most commonly used technique that can discriminate chiral molecule lacks sensitivity, preventing their use to study chirality in dilute media, such as gas phase molecule.
00:41
One solution to this issue is photoelectron circular dichroism, also known as PECD. In a PECD experiment, we send a jet of randomly oriented chiral molecules in a vacuum chamber where it can interacts with circularly polarized ionizing radiation. The photoelectron angular distribution is recorded by a velocity map imaging spectrometer.
01:06
When chiral molecules are ionized by circular light, more electrons can be emitted in the forward direction than backwards. This asymmetry is a pure electric dipole effect and is extremely strong. It can reach several tens of percents.
01:22
This is what our VMI spectrometer looks like. Recently, we showed that tabletop circularly polarized ex-UV photons from resonant ionic generation could be used to record PECD. We also investigated the influence of resonant enhancement in multi-photon ionization, showing that it is not necessary to observe PECD.
01:44
At higher laser intensity, we reached the above threshold ionization regime, where we have measured PECD, even for electrons ionized well above the ionization threshold. Last, we want to push the study to the tunneling regime. We used a strong 1.8 micron laser field to photo ionize the function molecules.
02:05
Remarkably, even in this extreme ionization regime, we still measured a significant PECD. We can thus conclude that PECD is a universal effect in the photo ionization of chiral molecules. This universality raised important questions. What is the physical origin of PECD? Is the process similar in single photon and tunnel ionization?
02:29
To answer this question, the most natural option seems to solve the time-dependent Schrodinger equation for molecules interacting with a laser pulse and monitor the evolution of the electronic density, which is the square modulus of the electronic wave function.
02:46
One can notice that because of the scattering of the outgoing electron onto the nuclei, the angular distribution of the freed electron gets structured. We can understand PECD as emerging from the scattering of the outgoing electron wave function on the chiral potential.
03:04
More precisely, PECD was found to be due to the scattering phases of the electrons. This interpretation is certainly valid, but scattering phases may not be the most intuitive quantity to think of. We thus wonder if there was a classical interpretation of the origin of PECD.
03:23
We solve the classical equation of motion of an electron in a circularly polarized laser field and a chiral molecular potential. The freed electron does not directly escape the molecule when it is ionized. It scatters several times on the molecular potential.
03:41
The physical origin of PECD can thus be classically understood in terms of scattering of the electron trajectories in the chiral potential, which is close to the quantum pictures. This is true for any laser wavelength and explains the universality of PECD. If you want to know more, you can read our paper in New Journal of Physic Fast Track Communications. Enjoy!