Title: Retrieval of full angular- and energy-dependent complex transition dipoles in the molecular frame from laser-induced high-order harmonic signals with aligned molecules

Abstract

High-order harmonic signals generated in molecules are the consequence of coherent summation of complex laser-induced transition dipoles $$\textit{d}(θ, ω)$$ with each fixed-in-space molecule; here $$\theta$$ is the angle of the molecular axis with respect to the laser polarization axis and $$\omega$$ is the harmonic energy. In the so-called rotational coherent spectroscopy, it is proposed to extract the fixed-in-space $$\textit{d}(θ, ω)$$ in the molecular frame by measuring harmonics generated by a probing laser from the rotational molecular wave packets that have been prepared by a prior pump laser. By varying the time delay between the two lasers, methods have been utilized to extract the $$\theta$$ dependence of both the amplitude and phase of each individual harmonic, but the relative phase between harmonics cannot be retrieved. Here we report that this limitation can be removed. It requires the additional measurement of harmonic spectra versus the pump-probe angles at one fixed time delay. The two-dimensional input harmonic data (time-delay and pump-probe angle) are then used to retrieve the full complex transition dipole $$\textit{d}(θ, ω)$$ using a retrieval method based on machine learning algorithms. Finally, we demonstrate this method on N₂ and CO₂ molecules.

Authors:

Wang, Bincheng  ^[1];

• Search DOE PAGES for author "Wang, Bincheng"
• Search DOE PAGES for ORCID "0000-0002-8471-5585"

He, Yanqing ^[2]; Zhao, Xi  ^[3];

• Search DOE PAGES for author "Zhao, Xi"
• Search DOE PAGES for ORCID "0000-0003-3114-5416"

He, Lixin ^[2]; Lan, Pengfei ^[2]; Lu, Peixiang ^[2]; Lin, C. D. ^[3]

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+ Show Author Affiliations

1. Huazhong Univ. of Science and Technology, Wuhan (China); Wuhan Institute of Technology (China)
2. Huazhong Univ. of Science and Technology, Wuhan (China)
3. Wuhan Institute of Technology (China)

Publication Date:

Tue Jun 30 00:00:00 EDT 2020

Research Org.:

Kansas State Univ., Manhattan, KS (United States)

Sponsoring Org.:

National Key R&D Program; National Natural Science Foundation of China (NSFC); China Scholarship Council (CSC); USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences & Biosciences Division

OSTI Identifier:

1800612

Grant/Contract Number:  

FG02-86ER13491

Resource Type:

Accepted Manuscript

Journal Name:

Physical Review A

Additional Journal Information:

Journal Volume: 101; Journal Issue: 6; Journal ID: ISSN 2469-9926

Publisher:

American Physical Society (APS)

Country of Publication:

United States

Language:

English

Subject:

74 ATOMIC AND MOLECULAR PHYSICS; Optics; Physics