Resolving Multiple Molecular Orbitals Using Two-Dimensional High-Harmonic Spectroscopy

Yun, Hyeok; Lee, Kyung-Min; Sung, Jae Hee; Kim, Kyung Taec; Kim, Hyung Taek; Nam, Chang Hee

doi:10.1103/physrevlett.114.153901

Cited by 43 publications

(30 citation statements)

References 25 publications

(27 reference statements)

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“…The summation in equation (9) extends over all saddle points, st, each representing a recolliding electron trajectory responsible of the harmonic emission at frequency ω = p 2 st /2m . Each rescattering corresponds to a term in the summation in equation (9), therefore, in selecting a single rescattering event from the TDSE time-frequency maps, we are isolating a single term in the summation. Thus, in this case, equation (8) follows directly from equation (9).…”

Section: Extraction Of the Form Factor From The Harmonic Spectramentioning

confidence: 99%

“…Each rescattering corresponds to a term in the summation in equation (9), therefore, in selecting a single rescattering event from the TDSE time-frequency maps, we are isolating a single term in the summation. Thus, in this case, equation (8) follows directly from equation (9). Figure 5(c) shows the comparison of the form factor extracted from the TDSE, F TDSE , using equation (8), against the s-SFA form factor, F s , and the modified SDT-SFA version, F SDT .…”

Section: Extraction Of the Form Factor From The Harmonic Spectramentioning

confidence: 99%

“…The harmonic spectra encode information of the target structure and dynamics, that can be disentangled using high-harmonic spectroscopy (HHS) and time resolved attosecond spectroscopy techniques [3]. These procedures have been successful in retrieving the information from the HHG spectra about molecular structure [4][5][6], nuclear dynamics [7], molecular orbitals [8,9], energy dispersion in solids [10], dynamics in strongly correlated systems [11], tunneling times [12], and orbital tomography [13][14][15].…”

Section: Introductionmentioning

confidence: 99%

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Site-specific tunnel-ionization in high harmonic generation in molecules

et al. 2020

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We demonstrate that the standard picture of strong-field tunnel-ionization from molecules should be reformulated. The extended nature of the molecular potential implies the separation of some of the molecular sites from the edge of the ionization barrier. We show that the dependence of the tunnel probability with the distance to the barrier is translated into the ionized wavepacket, modifying substantially the high-order harmonic emission. The introduction of the dependence of tunnel ionization with the molecular site significantly improves the theoretical description of high-order harmonic generation in molecules, which is used as a cornerstone in high-harmonic spectroscopy and attosecond imaging.

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Section: Extraction Of the Form Factor From The Harmonic Spectramentioning

confidence: 99%

Section: Extraction Of the Form Factor From The Harmonic Spectramentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Site-specific tunnel-ionization in high harmonic generation in molecules

et al. 2020

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“…Recently, driving fields with nonvanishing ellipticity have attracted a great deal of attention as potential attosecond imaging tools [1][2][3][4][5]. In particular, with regard to molecules, these types of fields provide access to a whole parameter range which would not be accessible otherwise.…”

Section: Introductionmentioning

confidence: 99%

Extracting an electron's angle of return from shifted interference patterns in macroscopic high-order-harmonic spectra of diatomic molecules

et al. 2015

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We investigate high-order harmonic spectra from aligned diatomic molecules in intense driving fields whose components have orthogonal polarizations. We focus on how the driving-field ellipticity influences structural interference patterns in a macroscopic medium. In a previous publication [Phys. Rev. A 88, 023404 (2013)] we have shown that the non-vanishing ellipticity introduces an effective dynamic shift in the angle for which the two-center interference maxima and minima occur, with regard to the existing condition for linearly polarized fields. In this work we show through simulation that it is still possible to observe this shift in harmonic spectra that have undergone macroscopic propagation, and discuss the parameter range for doing so. These features are investigated for H2 in a bichromatic field composed of two orthogonally polarized waves. The shift is visible both in the near-and in the far-field regime, so that, in principle, it can be observed in experiments.

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Enhanced two-color high-harmonic generation achieved by adding an extra gas medium

et al. 2015

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imaging [4], interferometry [5], and also for the exploration of atomic and molecular structures [6,7]. This novel XUV source, however, has a significant drawback of low conversion efficiency, and various schemes have been developed to improve it. The employment of a loose focusing geometry to a long gas cell was successful in boosting the harmonic yield to a μJ level in the 40-nm region by increasing the interaction cross section and length [8,9]. Spatial modification to a specific profile, such as flat-top shape, was also successful in expanding the effective harmonic generation volume [10,11]. Methods using waveguide structures have been investigated in order to improve phase matching between a driving laser pulse and generated harmonics [12,13]. These efforts made it possible to apply high-harmonic light source to specific applications such as XUV spectroscopy and microscopy, while it should be enhanced further to improve the applicability.Another approach developed to significantly enhance harmonic efficiency is the use of a synthesized laser field. As a simple synthesized field, a two-color laser field, consisting of a fundamental laser field and its second harmonic (SH), was applied to HHG [14,15]. It significantly improved the harmonic efficiency by generating short-path harmonics from atoms under a strongly ionizing condition, as compared to single-color harmonics generated under a weak ionization condition. We applied the strong harmonic by a two-color laser field to soft X-ray imaging experiments [4], and we found that the intensity of harmonic source should be improved further to enhance the spatial resolution of single-shot microscopy. More recently, twogas schemes were proposed to enhance the harmonic efficiency using a mixed gas medium or two gas cells [16,17]. In order to enhance the harmonic intensity further, the twogas media approach can be employed in two-color HHG scheme. AbstractThe high-harmonic generation in a two-color laser field, consisting of a 30-fs Ti:Sapphire laser pulse and its second harmonic, could be enhanced by installing an extra gas medium of Ar in front of the harmonic generation medium of He. The effects of the extra medium were examined by analyzing harmonic spectra taken under different experimental conditions. The observed characteristics of enhanced harmonic generation were explained in terms of the profile modification of the two-color laser beam. The 34th harmonic at 23.5 nm and 38th harmonic at 21.5 nm were enhanced 2.5 and 2 times, respectively.

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Resolving Multiple Molecular Orbitals Using Two-Dimensional High-Harmonic Spectroscopy

Cited by 43 publications

References 25 publications

Site-specific tunnel-ionization in high harmonic generation in molecules

Site-specific tunnel-ionization in high harmonic generation in molecules

Extracting an electron's angle of return from shifted interference patterns in macroscopic high-order-harmonic spectra of diatomic molecules

Enhanced two-color high-harmonic generation achieved by adding an extra gas medium

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