03-Jan-2019 - Max-Born-Institut (MBI) im Forschungsverbund Berlin e.V

Looking at molecules from two sides with table-top femtosecond soft-X-rays

X-ray spectroscopy provides direct access into the nature of chemical bonds, from which the outcome of chemical reactions can be understood. For this, intense activities both at x-ray source development and implementation of new measurement methods is pursued by key research labs. Researchers at the MBI have now successfully combined a table-top laser-based extreme high-order harmonic source for short-pulse soft-x-ray absorption spectroscopy in the water window with novel flatjet technology. They are the first to demonstrate the simultaneous probing of carbon and nitrogen atoms in organic molecules in aqueous solution.

X-ray absorption spectroscopy (XAS) monitors unoccupied electronic orbitals with element specificity, from which the electronic structure can be derived. For the majority of organic molecules the soft-X-ray spectral region (100-1000 eV) is relevant, as K-edge transitions of low-Z elements (C, N, and O), and the L-edges of 3d metals are found there. XAS is typically performed at large scale facilities, such as storage rings or free-electron lasers. Table-top laser-based sources have until now only been sparsely used to probe pure materials, e.g., metals and organic films. So far, measurements of the carbon or nitrogen K-edges of organic molecules in dilute aqueous solution have not been reported.

The research team at the MBI has now developed a bright source of femtosecond soft X-ray pulses, making use of the extreme high-order harmonic generation process. Long-wavelength (1.8 µm) driver pulses generated with an amplified Ti:sapphire laser system were used to generate high-order harmonics well above the conventional spectral range, i.e., now extending up to 450 eV. They have combined this source with liquid flatjet technology fully functioning under vacuum conditions. Steady-state absorption spectra of organic molecules and inorganic salts in a thin (~ 1 µm) sheet of aqueous solution can now be measured, throughout the so-called water window region between 200-540 eV (see Fig. 1). In particular, this technique enables the simultaneous local probing at both carbon and nitrogen sites within the molecules. With this the research team demonstrates the feasibility of following multiple sites within molecular systems, with the potential of probing possible correlations between these sites upon molecular rearrangements.

This investigation represents a major step towards the systematic investigation of ultrafast rearrangements of solution phase molecular systems with femtosecond soft X-ray spectroscopy. New insights into ultrafast charge transport processes and photo-induced reactions in chemistry and biology are envisaged to become accessible.

Facts, background information, dossiers

  • x-ray spectroscopy
  • x-ray absorption sp…
  • nitrogen

More about MBI

  • News

    Atom-Billiards with X-Rays

    In 1921, Albert Einstein received the Nobel Prize in physics for the discovery that light is quantized, interacting with matter as a stream of particles called photons. Since these early days of quantum mechanics, it is known that photons also possess momentum. The photon’s ability to trans ... more

    Scientists synthesized light with new intrinsic chirality to tell mirror molecules apart

    Light is the fastest way to distinguish right- and left-handed chiral molecules, which has important applications in chemistry and biology. However, ordinary light only weakly senses molecular handedness. Researchers from the Max Born Institute for Nonlinear Optics and Short Pulse Spectrosc ... more

    Forward or backward? New pathways for protons in water or methanol

    A collaborative ultrafast spectroscopy and ab initio molecular dynamics simulations study, as recently published by scientists of the Max Born Institute of Nonlinear Optics and Short Pulse Spectroscopy (MBI) and the Martin-Luther-University Halle-Wittenberg (MLU) in the Journal of the Ameri ... more

More about Forschungsverbund Berlin

q&more – the networking platform for quality excellence in lab and process

The q&more concept is to increase the visibility of recent research and innovative solutions, and support the exchange of knowledge. In the broad spectrum of subjects covered, the focus is on achieving maximum quality in highly innovative sectors. As a modern knowledge platform, q&more offers market participants one-of-a-kind networking opportunities. Cutting-edge research is presented by authors of international repute. Attractively presented in a high-quality context, and published in German and English, the original articles introduce new concepts and highlight unconventional solution strategies.

> more about q&more

q&more is supported by: