Tunnel ionization-assisted laser-induced electron diffraction (TI-LIED) has been successfully demonstrated as an effective technique for distinguishing structural isomers such as butane and isobutane [C.-H. Yuen et al. (unpublished)]. The inclusion of the tunnel ionization rate becomes increasingly important for larger molecules, where it significantly influences the scattering signal. In this work we begin by revisiting prior studies on two stereoisomers, 1,2-dichloroethylene (${\mathrm{C}}_2{\mathrm{H}}_2{\mathrm{Cl}}_2$) and 2-butene (${\mathrm{C}}_4{\mathrm{H}}_8$), which were previously shown to be distinguishable through their high-harmonic generation (HHG) spectra. We show that TI-LIED amplifies the scattering signal by different amounts across these isomers, producing strong contrast that peaks at backscattering, and offering a simpler, more direct alternative to HHG-based methods. Next, we demonstrate that TI-LIED has broader applicability beyond the identification of isomers. To illustrate this, we apply the method to two additional scenarios. The first examines structurally similar, but nonisomeric, molecules. An example used here is acetylene and diacetylene. TI-LIED successfully differentiates these molecules, highlighting its potential for resolving closely related molecular structures. The second case features dynamic molecules. We use the symmetric N-N stretching mode of ${\mathrm{N}}_2{\mathrm{O}}_4$ as an example. As the N-N bond length ($R_{NN}$) varies, the backscattering differential cross section oscillates strongly with $R_{NN}$ with the inclusion of TI rate, clearly reflecting the underlying structural change. With the progression of molecular imaging toward more complex species, TI-LIED is expected to become an increasingly important tool for structural analysis.

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• Atomic & molecular processes in external fields
• Atomic & molecular structure
• Strong-field-induced spectra
• Photoelectron diffraction