Circular dichroism in high-order harmonic generation from chiral molecules

Harada, Yōichi; Haraguchi, Eisuke; Kaneshima, Keisuke; Sekikawa, Taro

doi:10.1103/physreva.98.021401

Cited by 54 publications

(40 citation statements)

References 31 publications

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“…This approach is general and can be applied via an infinite set of geometries [i.e., our suggested schemes (A), (B), and (C) are representative.] Remarkably, the technique results in extremely high chiral/achiral sensitivity of up to 99%, which outperforms, by far, the ability of previous cHHG techniques to discern chiral media [28][29][30][31][32][33]. It also allows direct access to the medium's handedness by measuring the harmonic's helicities, which change sign when the medium's handedness is switched.…”

Section: Discussionmentioning

confidence: 95%

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Ultrasensitive Chiral Spectroscopy by Dynamical Symmetry Breaking in High Harmonic Generation

et al. 2019

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We propose and numerically demonstrate a new chiral spectroscopy method that is based on a universal system-independent mechanism of dynamical symmetry breaking in high harmonic generation (HHG). The proposed technique relies only on intense electric-dipole transitions and not on their interplay with magnetic dipole transitions. The symmetry breaking results in the emission of otherwise "forbidden" harmonics from chiral media (i.e., that are not emitted from achiral or racemic media), yielding a huge, nearly background-free, chiral-achiral signal that is correlated to the magnitude of the medium's enantiomeric excess. The handedness of the medium can be directly detected by measuring the polarization helicity of the emitted harmonics. Moreover, the strength of the "allowed" harmonics (that are not related to symmetry breaking) is chirality independent; hence, they can be used as a reference to probe chiral degrees of freedom within a single measurement. We numerically demonstrate up to 99% chiral-achiral signal level (normalized difference between the chiral and achiral HHG spectra) from microscopic gas-phase emission using state-of-the-art models for HHG in bromochlorofluoromethane and propylene oxide. We expect the new method to give rise to precise tabletop characterization of chiral media in the gas phase and for highly sensitive time-resolved probing of dynamical chiral processes with femtosecond-to-attosecond temporal resolution.

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Section: Discussionmentioning

confidence: 95%

“…Recently, it was also discovered that high harmonic generation (HHG) with a helically polarized pump is chirality sensitive [28][29][30][31][32][33]. In chiral HHG (cHHG), a chiral medium is irradiated with an intense laser field, and the emission spectrum is measured.…”

Section: Introductionmentioning

confidence: 99%

Ultrasensitive Chiral Spectroscopy by Dynamical Symmetry Breaking in High Harmonic Generation

et al. 2019

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“…[39], Fleischer et al reported on the observation of a 30%-chiral effect. Using an experimental scheme based on the detection of photoelectrons generated in a krypton gas target employing BHHG radiation, Harada et al [40] found a pronounced difference in the responses of the (R) and the (S) enantiomers of gas-phase limonene.…”

Section: Introductionmentioning

confidence: 99%

Chiral Discrimination through Bielliptical High-Harmonic Spectroscopy

Baykusheva

Wörner

2018

Phys. Rev. X

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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 AE 0.2% (at 17.6 eV). Using two circularly polarized fields, we observe circular dichroisms ranging up to 13 AE 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.

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“…HHG has been theoretically studied for decades using a variety of methods [15][16][17][18][19]. Over the last few years, as both the theoretical and experimental attoscience shifts towards increasingly more complex systems including solids [20,21] and biomolecules [22][23][24], the real-time propagation of the wavefunction using time-dependent * awozniak@chem.uw.edu.pl quantum chemical methods coupled to L 2 -integrable basis sets have gained some recognition in describing the electron dynamics during attosecond processes [19,[25][26][27][28]. Due to a better scaling with the number of electrons and much easier handling of multicenter systems, they are slowly surpassing the purely numerical, grid-based approaches.…”

Section: Introductionmentioning

confidence: 99%

Effects of electronic correlation on the high harmonic generation in helium: a time-dependent configuration interaction singles vs time-dependent full configuration interaction study

Woźniak,

Przybytek,

Lewenstein

et al. 2022

Preprint

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In this paper, we investigate the effects of full electronic correlation on the high harmonic generation in the helium atom subjected to laser pulses of extremely high intensity. To do this, we perform real-time propagations of the helium atom wavefunction using quantum chemistry methods coupled to Gaussian basis sets. The calculations are done within the real-time time-dependent configuration interaction framework, at two levels of theory: time-dependent configuration interation with single excitations (TD-CIS, uncorrelated method) and time-dependent full configuration interaction (TD-FCI, fully correlated method), and analyse obtained HHG spectra. The electronic wavefunction is expanded in Dunning basis sets supplemented with functions adapted to describing highly excited continuum states. We also compare the TD-CI results with grid-based propagations of the helium atom within the single-active-electron approximation. Our results show when including the dynamical electron correlation, a noticeable improvement to the description of HHG can be achieved, in terms of e.g. a more constant intensity in the lower energy part of the harmonic plateau. However, such effects can be captured only if the basis set used suffices to reproduce the most basic features, such as the HHG cutoff position, at the uncorrelated level of theory.

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Circular dichroism in high-order harmonic generation from chiral molecules

Cited by 54 publications

References 31 publications

Ultrasensitive Chiral Spectroscopy by Dynamical Symmetry Breaking in High Harmonic Generation

Ultrasensitive Chiral Spectroscopy by Dynamical Symmetry Breaking in High Harmonic Generation

Chiral Discrimination through Bielliptical High-Harmonic Spectroscopy

Effects of electronic correlation on the high harmonic generation in helium: a time-dependent configuration interaction singles vs time-dependent full configuration interaction study

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