Opportunities for chiral discrimination using high harmonic generation in tailored laser fields

Abstract

Abstract. Chiral discrimination with high harmonic generation (cHHG method) has been introduced in the recent work by R. Cireasa et al (Nat. Phys. 11, 654 -658, 2015). In its original implementation, the cHHG method works by detecting high harmonic emission from randomly oriented ensemble of chiral molecules driven by elliptically polarized field, as a function of ellipticity. Here we discuss future perspectives in the development of this novel method, the ways of increasing chiral dichroism using tailored laser pulses, new detection schemes involving high harmonic phase measurements, and concentration-independent approaches. Using the example of the epoxypropane molecule C 3 H 6 O (also known as 1,2-propylene oxide), we show theoretically that application of two-color counter-rotating elliptically polarized laser fields yields an order of magnitude enhancement of chiral dichroism compared to single color elliptical fields. We also describe how one can introduce a new functionality to cHHG: concentration-independent measurement of the enatiomeric excess in a mixture of randomly oriented left-handed and right-handed molecules. Finally, for arbitrary configurations of laser fields, we connect the observables of the cHHG method to the amplitude and phase of chiral response, providing a basis for reconstructing wide range of chiral dynamics from cHHG measurements, with femtosecond to sub-femtosecond temporal resolution.

Attosecond control of spin polarization in electron-ion recollision driven by intense tailored fields

“…Electron spin and orbital angular momentum can play an important role in well-established recollision-driven techniques such as photoelectron diffrac-tion and holography [35][36][37][38][39][40] or high harmonic generation [24,26,29,32,[41][42][43][44][45]. We have shown that the use of intense two-color counter-rotating bi-circular fields can drive electroncore recollision with a degree of spin polarization that depends on the recollision time and therefore on the recollision energy.…”

“…The application of bi-circular fields can lead to the production of ultrashort circularly and elliptically polarized laser pulses in the XUV domain [25][26][27][28][29][30][31]. Their chiral nature offers unique possibilities for probing molecular chirality [32] or symmetry breaking [33] at their natural time scales via high harmonic generation spectroscopy. Recent theoretical work [13] has indicated that electrons produced upon strong field ionization with bi-circular fields are spin polarized.…”

Chiral separation and twin-beam photonics

“…The very latest, wide-ranging research discuss: the origin of homochirality in amino acids and sugars; 25 the control of chirality in crystalline growth; 26 the separation of charge using chiral molecules; 27 the detection of enantiomers in a mixture through highharmonic generation, 28,29 and chiral scattering as the source of orbital angular momentum transfer between an acoustic beam and matter. 30 In this work, our novel mechanism for enantiomer separation is outlined and we can conclude that the additional complexities involved in a two-beam technique would not provide any advantages over a single beam set-up; the mechanism is higher-order than the one beam scenario and, thus, produces weaker effects and a differential chiral force that is three orders of magnitude smaller than the single beam case.…”

Quantum formulation for nanoscale optical and material chirality: symmetry issues, space and time parity, and observables

“…One of the main or implicit motivations for several of the recent studies in this area is the prospect of achieving, by optical means, a separation of particles-especially chiral molecules-of opposite handedness [7,10,43,[98][99][100][101][102][103][104][105][106][107][108][133][134][135][136][137][138][139][140][141][142][143][144][145]. Certainly such a capacity might have important commercial applications-notably in the pharmaceutical industry, where oppositely handed compounds can deliver drastically different effects.…”