In this talk I will introduce atomic-scale X-ray photon correlation spectroscopy, a synchrotron-based experimental method that allows us to follow the atoms during their movement in real time in a statistical sense, with a sensitivity to jump rates on timescales of seconds to hours [1]. I will review the theoretical concepts and discuss the relations to alternative atomically-resolved methods. Further, I will give an overview on our results in crystalline and amorphous matter, comprising metals, semiconductors and insulators.

Diffusion is an omnipresent phenomenon in nature. In the world of molecules, it describes their irregular thermal motion. The interplay of diffusion and interaction of molecules with pore walls of nanoporous materials constitutes the benefit of using such materials in applications of separation and catalysis. The need for understanding the rate-limiting mechanisms, further optimization and development of new processes makes this topic subject of continued fundamental research [1].

Adolf Fick’s work represents in many ways an important starting point for modern scientific research on diffusion. Diffusion itself is a slow process taking long time to progress. In this talk, we aim to discuss the progress of diffusion science. For this purpose, we present a highly subjective review of the study of diffusion since the times of Adolf Fick. Our focus is on mutual diffusion in liquids which is at the heart of many processes in (bio)chemical systems. Here, diffusion is often the rate-limiting step and thus decisive for overall process performance.

MgO, Al2O3 and MgF2 are three wide gap insulating materials with different crystalline structures. All three materials are radiation resistant and have many important applications, e.g. in reactor optical windows. It is very important to predict their long-time defect structure evolution controlled by defect migration and reactions. One could estimate the diffusion coefficients of radiation defects in solids from measurements of the main defect concentration changes (oxygen vacancies called the F-type color centers, by optical absorption) under different conditions, e.g., sample heating (annealing) after irradiation.

The workshop program will focus on adsorption measurement techniques and methodologies for the assessment of adsorption properties and textural/structural characterization of novel nanoporous materials including zeolites, carbons, MOFs as well as materials consisting of hierarchically structured pore networks. A major point will be the correlation of textural properties, adsorption behavior, catalytic reaction pathways as well as transport properties with applications in gas and energy storage, separations and catalysis. Within this framework, the workshop will offer a platform for scientific discussions and for a knowledge transfer between various scientific areas where diffusion and transport properties of porous materials are of importance.

With reference to these advantages, the poster goes the other way round and identifies a couple of similarities where, on looking at molecular diffusion in nanoporous materials, one is able to recognize features of spreading, which may occur in quite different fields of research. The examples presented include (i) considering molecular uptake and release with nanoporous particles as a model for, respectively, occupation of a habitat by a new species and, vice versa, for the loss of a species in this habitat [2], (ii) the effect of additional highways on overall mass transfer [3,4], (iii) transport impediment (and enhancement!) by diffusant interference [5], (iv) invader-induced changes in the host system [2] and (v) host-induced changes of the invaders [6].

As supplier and producing company in the adsorption field, we study diffusion phenomena both related to adsorption and in business field development. In the context of pure gas adsorption for texture characterization of porous materials we find phenomena which are easy to explain, e.g., the blockage of narrow micropores in Zeolith 4A dependent on the measuring temperature (see Fig. 1). Fig. 2 shows temperature profiles and breakthrough curves of mixed gas and vapor adsorption studies, measured with the 3P mixSorb dynamic sorption analyzer [3].

Vital nutrients, accumulated wastes and therapeutic agents are all transported by diffusion in their journey through brain tissues. 3D computational models of the brain that predict species transport have proven helpful in regional analysis of disease and drug delivery. In our group, we have developed computational models using magnetic resonance diffusion tensor imaging (DTI) data sets that account for heterogeneity and anisotropy of transport. To date, we have used these models to predict spatial depositions following brain infusions.

Single-particle tracking experiments have measured the distribution of dwell times of various DNAbinding species — including CRISPR-Cas9, TetR, and LacI — diffusing in living cells. The observed truncated power law distribution has direct and indirect implications. One direct implication is that the observed dwell time distribution is inconsistent with the Gaussian distribution of binding energies generally obtained from bioinformatics. Consideration of length scales of the nucleus and the measurement is essential to understanding the dwell time distribution.

Since conformation changes of proteins and biomolecular interactions (including protein-DNA, or protein-protein interactions) are essential processes for biological functions, detections of these processes are important in chemistry and biochemistry to understand the reactions. For the detection of these processes, a variety of techniques have been developed. UV/vis absorption spectroscopy or emission spectroscopy are very powerful to trace the time development of reactions. However, these techniques have a limitation to detect the conformation changes of proteins and biomolecular interactions. Recently, our group discovered that the translational diffusion coefficient can be a useful and sensitive probe to detect the conformation change as well as the intermolecular interaction changes. Although many techniques, e.g., dynamic light scattering, Taylor dispersion, capillary method, NMR spectroscopy, have been developed to monitor molecular diffusion, molecular diffusion has never been considered as a time dependent property during reactions. We have been developing a method based on the pulsed-laser induced transient grating (TG) technique to detect the time-dependent diffusion. Here, we repot the time-resolved detection of protein conformation changes of a blue light sensor protein of phototropin by using the diffusion coefficient.