MANA International Symposium 2025

Session 3-2

Title

Excited state formation in a single molecule with terahertz-induced ultrafast charge transfer

Authors

Ikufumi Katayama

Affiliations

Yokohama National University

URL

https://ultrafast.ynu.ac.jp/

katayama-ikufumi-bm@ynu.ac.jp

Abstract

To establish a method for investigating ultrafast dynamics after charge transfer, we combined terahertz time-domain spectroscopy with scanning tunneling luminescence spectroscopy. The sequential charge transfer between a metal tip and a single molecule enables us to dynamically generate an excited state in the molecule. The efficiency of the resultant luminescence can be controlled with the phase of the terahertz pulse, indicating importance of dynamical changes in quantum energy levels of the molecule. Our method offers a new platform for investigating dynamics of chemical reactions induced by ultrafast charge transfer.

Fig. 1. Schematic of the terahertz scanning tunneling luminescence spectroscopy. A terahertz pulse induces the charge transfer to the molecule, creating the excited state to emit luminescence.

Fig. 2. Luminescence spectra from Pd-phthalocyanine molecule at 4 K with and without THz pulses. Inset shows DC and THz scanning tunneling microscope image of the molecule.

Reference

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K. Kimura et al., ACS Photon. 8, pp. 982-987 (2021). DOI: 10.1021/acsphotonics.0c01755
K. Yoshioka et al., Nano Lett. 18, pp. 5198-5204 (2018). DOI: 10.1021/acs.nanolett.8b02161