Coherent diffractive imaging of single helium nanodroplets with a high harmonic generation source

Daniela Rupp,Luca Poletto,Bruno Langbehn,Francesca Calegari,Mario Sauppe,Andrea Trabattoni,Thomas Möller,Yevheniy Ovcharenko,Fabio Frassetto,Arnaud Rouzée,Christian Peltz,Mauro Nisoli,Marc J Vrakking,Nils Monserud,Julian Zimmermann,Thomas Fennel,Katharina Sander

doi:10.1038/s41467-017-00287-z

Abstract

Coherent diffractive imaging of individual free nanoparticles has opened routes for the in situ analysis of their transient structural, optical, and electronic properties. So far, single-shot single-particle diffraction was assumed to be feasible only at extreme ultraviolet and X-ray free-electron lasers, restricting this research field to large-scale facilities. Here we demonstrate single-shot imaging of isolated helium nanodroplets using extreme ultraviolet pulses from a femtosecond-laser-driven high harmonic source. We obtain bright wide-angle scattering patterns, that allow us to uniquely identify hitherto unresolved prolate shapes of superfluid helium droplets. Our results mark the advent of single-shot gas-phase nanoscopy with lab-based short-wavelength pulses and pave the way to ultrafast coherent diffractive imaging with phase-controlled multicolor fields and attosecond pulses.

Highlights

Single-shot coherent diffractive imaging (CDI) with intense short-wavelength pulses became possible just recently with the advent of extreme ultraviolet (XUV) and X-ray freeelectron lasers (FEL)[1]
About 12 mJ were loosely focused (f = 5 m) into a xenon-filled gas cell[24], producing ≈2 μJ of XUV radiation, i.e., close to 1012 photons per pulse. This corresponds to ~1% of the pulse energy that can currently be achieved at the XUV freeelectron laser FERMI25
We have shown the feasibility of single-shot single-particle CDI using intense XUV pulses from a high harmonic generation (HHG) source

Summary

Introduction

Single-shot coherent diffractive imaging (CDI) with intense short-wavelength pulses became possible just recently with the advent of extreme ultraviolet (XUV) and X-ray freeelectron lasers (FEL)[1] This lensless imaging method has revolutionized the structural characterization of nanoscale samples, including biological specimens[2], aerosols[3], atomic clusters[4,5,6], and nanocrystals[7]. For sufficiently regular structures the wide-angle scattering information even reveals the full three-dimensional particle shape and orientation[6,7,8], as multiple projections of the same particle are encoded in a single diffraction image[6] These unique capabilities enable the investigation of metastable or transient states that exist only in the gas phase. We report the feasibility of lab-based 3D characterization of unsupported nanoparticles and demonstrate single-shot HHG-CDI on individual free helium nanodroplets

Methods

Results

Conclusion