Picosecond pulse-shaping for strong three-dimensional field-free alignment of generic asymmetric-top molecules

• Published in: Nature communications 2022-03, Vol.13 (1), p.1431-7, Article 1431
• Main Authors: Mullins, Terry, Karamatskos, Evangelos T., Wiese, Joss, Onvlee, Jolijn, Rouzée, Arnaud, Yachmenev, Andrey, Trippel, Sebastian, Küpper, Jochen
• Format: Article
• Language: English
• Subjects: 639/638/440; 639/766/36; 639/766/930; Alignment; Angular velocity; Asymmetry; Broadband; Computer applications; Femtosecond pulses; Field ionization; Humanities and Social Sciences; Imaging; Ion velocity; Ionization; Lasers; Molecular dynamics; Molecular structure; multidisciplinary; Picosecond pulses; Science; Science (multidisciplinary); Spatial light modulators; Velocity
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-022-28951-z

Fixing molecules in space is a crucial step for the imaging of molecular structure and dynamics. Here, we demonstrate three-dimensional (3D) field-free alignment of the prototypical asymmetric top molecule indole using elliptically polarized, shaped, off-resonant laser pulses. A truncated laser pulse is produced using a combination of extreme linear chirping and controlled phase and amplitude shaping using a spatial-light-modulator (SLM) based pulse shaper of a broadband laser pulse. The angular confinement is detected through velocity-map imaging of H + and C 2+ fragments resulting from strong-field ionization and Coulomb explosion of the aligned molecules by intense femtosecond laser pulses. The achieved three-dimensional alignment is characterized by comparing the result of ion-velocity-map measurements for different alignment directions and for different times during and after the alignment laser pulse to accurate computational results. The achieved strong three-dimensional field-free alignment of < cos 2 δ > = 0.89 demonstrates the feasibility of both, strong three-dimensional alignment of generic complex molecules and its quantitative characterization. Field-free 3D alignment of complex molecules is an important step toward the imaging of molecular dynamics. Here, the authors demonstrate pulse-shaping of long picosecond pulses for the 3D field-free alignment of the prototypical non-rotation-symmetric molecule indole.