Femtosecond response of polyatomic molecules to ultra-intense hard X-rays

(DESY/Science Communication Lab)

The study of molecules with X-rays is of particular interest for biological and potentially pharmaceutical sciences. X-rays are here being used to resolve the shape or structure of a molecule. But when the X-rays interact with the molecules, the ionize the atoms the molecule consists of and the molecule is transformed into a nanoplasma. Such radiation damage is of particular interest, as a solid understanding of the underlying damaging processes is required to lead to high-res imaging. In the linked study that has been published in Nature, we investigate molecules using intense hard X-rays from the CXI instrument at LCLS reaching a never before seen level of ionization. The insights of this study help developing high-resolution imaging of bio molecules.

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Image from: DESY/Science Communication Lab

Measuring transient states of matter using incoherent scattering

Thomson Scattering MacDonald

Measuring transient states of matter on the femto- to attosecond timescale is a current scientific challenge. Particularly for nanometer sized objects, the size of biomolecules for example proteins, it is a challenge to measure signal above the noise level due to low cross-sections. The amount of photons LCLS produces can overcome signal-to-noise issues and opens the door to perform measurements in entirely new regimes. In the featured and recently published study, we make use of LCLS in such a new way and measure an incoherent signal much above the noise level. The basis of this experiments is to spectrally resolve the scattering from free electrons or Thomson scattering. The developed method allows another way to gain insight into transient states, for example, the nanoplasma transformation or chemical reactions that last on the atto- to picosecond timescale. Particularly, parameters such as (electron) temperature, density and ionization levels can be measured using the LAMP endstation at LCLS. To make the proof-of-principle study, a pump-probe scheme was employed that first used an IR laser to induce a transient state (nanoplasma) in a nano-sample (argon clusters) and then secondly, after a time-delay, measures this state using the X-rays LCLS.

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Coherent diffraction of Rice Dwarf virus at the Linac Coherent Light Source

nature data cover

In this study, we've applied coherent diffractive imaging to study the structure of a single Rice dwarf virus. The CXI instrument at the Linac coherent light source focuses 1012 photons into a nanometer-sized area. Here the X-rays scatter of a single virus particle and create a snapshot of the virus. The acquired dataset of this study has been published in Nature scientific data, that allows access to the actual dataset. The publication yields information on how to access the data and background information as well. This result comes out of a large collaboration, the Single particle initiative, where scientists from around the world have united to pull on one string and push the method of Single particle imaging to the next level.

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