Isomer Identification via Tunnel‑Ionization‑Weighted Laser‑Induced Electron Diffraction (LIED)

Determining molecular isomer structures is the prerequisite for realtime monitoring of molecular dynamics. Conventional electron diffraction techniques are primarily sensitive to adjacent bond structures, making it difficult to distinguish between isomers. Recent developments in laser induced electron diffraction (LIED) have shown that the tunnel ionization rate significantly modifies the scattering intensity, making the LIED signal sensitive to both nuclear geometry and electronic structure. This sensitivity has enabled discrimination between simple isomers such as n-butane and isobutane. In this work, we simulate the LIED signals of the more complex molecular isomers camphor, fenchone, and vertonal cations. Our results show that tunnel ionization rate–weighted scattering signals provide clear, distinguishable signatures for each isomer. These findings demonstrate LIED as a powerful approach for identifying molecular isomers, opening the door to using LIED for tracking molecular dynamics in real time.