X-ray diffraction from isolated and strongly aligned gas-phase molecules with a free-electron laser

TL;DR

This study demonstrates the feasibility of x-ray diffraction imaging of isolated, strongly aligned gas-phase molecules using free-electron laser pulses, enabling potential ultrafast molecular dynamics studies.

Contribution

It introduces a new experimental approach combining quantum-state selection, strong molecular alignment, and ultrashort x-ray pulses for single-molecule diffraction.

Findings

Successful detection of individual scattered x-ray photons.

Preparation of state-selected, aligned molecular ensembles.

Validation of techniques for ultrafast molecular imaging.

Abstract

We report experimental results on x-ray diffraction of quantum-state-selected and strongly aligned ensembles of the prototypical asymmetric rotor molecule 2,5-diiodobenzonitrile using the Linac Coherent Light Source. The experiments demonstrate first steps toward a new approach to diffractive imaging of distinct structures of individual, isolated gas-phase molecules. We confirm several key ingredients of single molecule diffraction experiments: the abilities to detect and count individual scattered x-ray photons in single shot diffraction data, to deliver state-selected, e. g., structural-isomer-selected, ensembles of molecules to the x-ray interaction volume, and to strongly align the scattering molecules. Our approach, using ultrashort x-ray pulses, is suitable to study ultrafast dynamics of isolated molecules.