Underlying physics of high-order harmonic generation from oriented molecules

2016 Fiscal Year Final Research Report

• Project/Area Number: 26247065
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Atomic/Molecular/Quantum electronics
• Research Institution: The University of Tokyo
• Principal Investigator: Sakai Hirofumi 東京大学, 大学院理学系研究科(理学部), 教授 (20322034)
• Co-Investigator(Renkei-kenkyūsha): MINEMOTO Shinichirou 東京大学, 大学院理学系研究科, 助教 (90323493)
• Research Collaborator: KATO Kosaku ; SAKEMI Yusuke ; MUN Je Hoi ; TAKEI Daisuke ; NAKAGAWA Kei
• Project Period (FY): 2014-04-01 – 2017-03-31
• Keywords: 原子・分子物理 / 気体分子の配列・配向制御 / 高次高調波発生 / 超閾イオン化 / 分子軌道イメージング / プラズマシャッター / 分子偏向器 / 六極集束器

Outline of Final Research Achievements

With an intense femtosecond two-color pulse optimized for the generation of even-order harmonics from CO molecules, we directly measure the actual degrees of orientation by utilizing the Coulomb explosion imaging technique with appropriate probe polarization. We find that the macroscopic orientation of CO molecules is negligible even when significant even-order harmonics are observed. This finding shows that the generation of even-order harmonics cannot be ascribed to the macroscopic orientation of CO molecules. The rotational wave packet of CO molecules created with an intense femtosecond two-color pulse is thought to be in an uninvestigated quantum state, which is beyond the Born-Oppenheimer approximation, without inversion symmetry at any of the three steps of high-order harmonic generation, leading to the generation of even-order harmonics.

Free Research Field

原子分子物理学実験