Circularly polarized high harmonic generation by non-perturbative magnetic dipole interaction between high laser field and chiral molecules

2021 Fiscal Year Final Research Report

• Project/Area Number: 19H01814
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 13020:Semiconductors, optical properties of condensed matter and atomic physics-related
• Research Institution: Hokkaido University
• Principal Investigator: SEKIKAWA TARO 北海道大学, 工学研究院, 准教授 (90282607)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: キラル分子 / 円偏光高次高調波 / 非摂動相互作用

Outline of Final Research Achievements

The composite electric field of the mutually orthogonal circularly polarized fundamental (ω) and its second harmonic (2ω) has three-fold symmetry, and the polarizations of the (3m+1)-th and (3m+2)-th orders of the generated circularly polarized high harmonics are the same as those of ω and 2ω polarization, respectively. The intensity ratio of the (3m+1)-th and (3m+2)-th orders generated from the noble gas depends on the magnetic quantum number of the outermost orbitals. Therefore, the intensity ratio of the (3m+1)-th and (3m+2)-th orders of the harmonic spectrum from chiral molecules with fixed chirality is expected to depend on the circular polarization. In this study, we confirmed the above-mentioned phenomenon in the high harmonic spectra generated from limonene and propylene oxide enantiomers.

Free Research Field

超高速光科学

Academic Significance and Societal Importance of the Research Achievements

生体関連分子や薬剤には鏡像異性体を持つものが多い。しかしその物理的な性質は同じであり、異性体の区別が難しい。通常用いられる円偏光の吸収の違い（円二色性）は1万分の１の違いしかない。今回発見した高次高調波発生の円偏光による違いは百分の1と大きい。そのため、高次高調波発生により容易に分子のキラリティの弁別を行うことができる可能性がある。生体反応においてキラル分子の選択性が重要な役割を果たしており、生体内のキラリティに依存する反応を観測することに適用できるであろう。