Open access
Datum
2018-09-10Typ
- Journal Article
Abstract
Molecular chirality plays an essential role in most biochemical processes. The observation and quantification of chirality-sensitive signals, however, remains extremely challenging, especially on ultrafast timescales and in dilute media. Here, we describe the experimental realization of an all-optical and ultrafast scheme for detecting chiral dynamics in molecules. This technique is based on high-harmonic generation by a combination of two-color counterrotating femtosecond laser pulses with polarization states tunable from linear to circular. We demonstrate two different implementations of chiral-sensitive high-harmonic spectroscopy on an ensemble of randomly oriented methyloxirane molecules in the gas phase. Using two elliptically polarized fields, we observe that the ellipticities maximizing the harmonic signal reach up to 4.4±0.2% (at 17.6 eV). Using two circularly polarized fields, we observe circular dichroisms ranging up to 13±6% (28.3–33.1 eV). Our theoretical analysis confirms that the observed chiral response originates from subfemtosecond electron dynamics driven by the magnetic component of the driving laser field. This assignment is supported by the experimental observation of a strong intensity dependence of the chiral effects and its agreement with theory. We moreover report and explain a pronounced variation of the signal strength and dichroism with the driving-field ellipticities and harmonic orders. Finally, we demonstrate the sensitivity of the experimental observables to the shape of the electron hole. This technique for chiral discrimination will yield femtosecond temporal resolution when integrated in a pump-probe scheme and subfemtosecond resolution on chiral charge migration in a self-probing scheme. Mehr anzeigen
Persistenter Link
https://doi.org/10.3929/ethz-b-000291145Publikationsstatus
publishedExterne Links
Zeitschrift / Serie
Physical Review XBand
Seiten / Artikelnummer
Verlag
American Physical SocietyOrganisationseinheit
03888 - Wörner, Hans Jakob / Wörner, Hans Jakob
Förderung
307270 - Measuring attosecond electron dynamics in molecules (EC)