Topic: 
Challenges and solutions for electron microscopy and spectroscopy in the field of chemical energy conversion 
Date: 
30.05.22 
Time: 
16:15 
Place: 
H6 & online 
Guest: 

MPI für Chemische Energiekonversion, Mülheim a.d.R 

Abstract: 
Analytical transmission electron microscopy (TEM) has become a widely implemented technique in a modern research institute involved in catalysis and materials science which are key topics in the field of chemical energy conversion. To get the full picture when investigating different materials and their properties, several analytical techniques available in TEM have to be combined and compared with the results of other analytical instruments. However, usually TEM specialists perform the necessary tasks for a thorough microscopical study of the materials of interest. The need for generating standard procedures and workflows optimized for nonexpert TEM users has been addressed in our ChemiTEM project. The developed workflows were implemented into a tablet app enabling nonexpert TEM users to perform even applications they have no previous experience with by guiding them through all necessary decision processes. The app also includes a workflow for data analysis. All this renders the set of standardized workflows a versatile toolbox for TEM applications in material synthesis and chemistry. In many cases, samples have to be investigated under inert conditions, e.g., when catalysts consist of reduced metals. We developed a new method to perform such investigations without the necessity to use dedicated sample holders but instead being able to harness the capabilities of standard sample holders. I will present some examples of the interplay of different analytical techniques as well as results of the ChemiTEM project and our inert investigation techniques. In addition, a short outlook on the development of standardized workflows for electron energyloss spectrometry (EELS) and Xray photoelectron spectroscopy (XPS) will be given. 
Contact person: 
Topic: 
tba 
Date: 
03.06.22 
Time: 
16:15 
Place: 
V4119 
Guest: 

University of Hamburg 

Abstract: 

Contact person: 
Topic: 
tba 
Date: 
30.06.22 
Time: 
14:15 
Place: 
D6135 
Guest: 

Universität Bern 

Abstract: 

Contact person: 
Topic: 
14.00 tba 
Date: 
03.06.22 
Time: 
14:00 
Place: 
ZOOM / Konferenzschaltung 
Guest: 
Jakub Mrozek 
University of Oxford 

Abstract: 

Contact person: 
Topic: 
Manyparticles diffusing with resetting: study of the largedeviation properties of the flux distribution 
Date: 
05.05.22 
Time: 
16:00 
Place: 
D5153 
Guest: 
Costantino Di Bello 
Abstract: 
In this paper we studied a model of noninteracting particles moving on a line following a common dynamics. In particular we considered either a diffusive motion with Poissonian resetting, and a runandtumble motion with Poissonian resetting. We were interested in studying the distribution of the random variable $Q_t$ defined as the flux of particles through origin up to time $t$. We used the notation $P(Q,t)$ to identify the probability $\mathbb{P}\{Q_t=Q\}$. We considered particles initially located on the negative half line with a fixed density $\rho$. In fully analogy with disordered systems, we studied both the annealed and the quenched case for initial conditions. In the former case we found that, independently from the specific dynamics, $P_\mathrm{an}(Q,t)$ has a Poissonian shape; while in the latter case, for what concerns the diffusive dynamics with resetting, the large deviation form of the quenched distribution reads $P_\mathrm{qu}(Q,t)\sim \exp\left[r^2t^2 \Psi_\mathrm{diff}\left(\dfrac{Q}{\rho t}\right)\right]$ with the large deviation function $\Psi_\mathrm{diff}(x)$ exhibiting a discontinuity in the third derivative, hence aiming, despite the simplicity of the model, at the exhistence of a dynamical phase transition. The quenched distribution for the runandtumble dynamics, instead, does not exhibit any kind of phase transition. Importance sampling Monte Carlo simulations were performed to prove the analytical results. References: Current fluctuations in noninteracting runandtumble particles in one dimension Tirthankar Banerjee, Satya N. Majumdar, Alberto Rosso, and Grégory Schehr, Phys. Rev. E 101, 052101 https://doi.org/10.1103/PhysRevE.101.052101 Current Fluctuations in One Dimensional Diffusive Systems with a Step Initial Density Profile B. Derrida and A. Gerschenfeld, J. Stat. Phys. 137, 978 (2009) https://doi.org/10.1007/s1095500998301 
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Topic: 
Exponential Functional of the Matrix Brownian Motion, Dufresne Identity and Quantum Scattering 
Date: 
25.05.22 
Time: 
09:00 
Place: 
ZOOM / Konferenzschaltung 
Guest: 

LPTMC, Sorbonne Université 

Abstract: 
Exponential functionals of the Brownian motion appear in many different contexts (classical diffusion in random media, quantum scattering, finance,...). I will discuss a recent generalization to the case of matrix Brownian motion. This problem has a natural motivation within the study of quantum scattering on a disordered wire with several conducting channels. I will show that the WignerSmith time delay matrix, a fundamental matrix in quantum scattering encoding several characteristic time scales, can be represented as an exponential functional of the matrix BM. I will discuss the relation between this problem of quantum physics and the Dufresne identity, which gives the stationary distribution of such exponential functionals of the BM. Ref: Aurélien Grabsch and Christophe Texier, WignerSmith matrix, exponential functional of the matrix Brownian motion and matrix Dufresne identity, J. Phys. A: Math. Theor. 53, 425003 (2020) 
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