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Updated: Jan 4, 2026

Direct Imaging of Laser-driven Ultrafast Molecular Rotation
Published on: February 4, 2017
Theory of ultrafast x-ray scattering by molecules in the gas phase
Mats Simmermacher1, Andrés Moreno Carrascosa1, Niels E Henriksen2
1EaStCHEM, School of Chemistry, University of Edinburgh, EH9 3FJ Edinburgh, United Kingdom.
Abstract:
We recast existing theory of ultrafast time-resolved x-ray scattering by molecules in the gas phase into a unified and coherent framework based on first-order time-dependent perturbation theory and quantum electrodynamics. The effect of the detection window is analyzed in detail and the contributions to the total scattering signal are discussed. This includes the coherent mixed component caused by interference between scattering amplitudes from different electronic states. A new, detailed, and fully converged simulation of ultrafast total x-ray scattering by excited H2 molecules illustrates the theory and demonstrates that the inelastic component can contribute strongly to the total difference scattering signal, i.e., on the same order of magnitude as the elastic component.
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