Computational studies of x-ray scattering from three-dimensionally-aligned asymmetric-top molecules

TL;DR

This paper presents a theoretical and numerical analysis of x-ray scattering from three-dimensionally aligned asymmetric-top molecules, demonstrating the potential for high-resolution molecular structure reconstruction using optimized laser and x-ray parameters.

Contribution

It introduces a computational framework for simulating x-ray scattering from aligned asymmetric-top molecules and assesses the feasibility of structure determination at atomic resolution.

Findings

Feasibility of 1 Å resolution structure reconstruction demonstrated.

Alignment and laser parameters critically influence spatial resolution.

Efficient solution of the Schrödinger equation enhances computational modeling.

Abstract

We theoretically and numerically analyze x-ray scattering from asymmetric-top molecules three-dimensionally aligned using elliptically polarized laser light. A rigid-rotor model is assumed. The principal axes of the polarizability tensor are assumed to coincide with the principal axes of the moment of inertia tensor. Several symmetries in the Hamiltonian are identified and exploited to enhance the efficiency of solving the time-dependent Schr\"odinger equation for each rotational state initially populated in a thermal ensemble. Using a phase-retrieval algorithm, the feasibility of structure reconstruction from a quasi-adiabatically-aligned sample is illustrated for the organic molecule naphthalene. The spatial resolution achievable strongly depends on the laser parameters, the initial rotational temperature, and the x-ray pulse duration. We demonstrate that for a laser peak intensity of 5 TW/cm^2, a laser pulse duration of 100 ps, a rotational temperature of 10 mK, and an x-ray pulse duration of 1 ps, the molecular structure may be probed at a resolution of 1 \AA.