Bonn 2025 – scientific programme

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MO: Fachverband Molekülphysik

MO 23: Cluster and Nanoparticles I (joint session MO/A)

MO 23.5: Talk

Thursday, March 13, 2025, 12:15–12:30, HS XV

Temperature and adsorption dynamics of single nanoparticles in a cryogenic ion trap — •Björn Bastian, Sophia C. Leippe, Kleopatra Papagrigoriou, and Knut R. Asmis — Wilhelm Ostwald Institute, Leipzig University, Linnéstraße 2, D-04103 Leipzig

Characterization of nanoparticles without inhomogeneous broadening and interactions with the environment requires single particle techniques in the gas phase. Our group has shown the feasibility of single nanoparticle action spectroscopy (SNAS) in a cryogenic Paul-type ion trap [1], based on the adsorption of messenger atoms or molecules on the nanoparticle surface and their desorption driven by laser heating with rates that are proportional to the absorption cross section [2].

A quantitative understanding of the sorption dependent SNAS technique and temperature programmed desorption schemes to characterize surface interactions strongly depend on the surface temperature which is difficult to measure or estimate in such experiments. In a collaborative work, we could achieve a first in situ measurement using the temperature-dependent emission spectrum of core/shell CdSe/CdS quantum dots and capture the essential heating and cooling processes in a model [3]. The latter helps to estimate surface temperatures for different particles and experimental conditions which is used here to interpret the adsorption dynamics of oxygen on silica nanoparticles.

[1] B. Hoffmann et al., Mol. Phys. 122, e2210454 (2023). [2] B. Hoffmann et al., J. Phys. Chem. Lett. 11, 6051 (2020). [3] S. C. Leippe et al., J. Phys. Chem. C (accepted).

Keywords: Single nanoparticle action spectroscopy; Single particle fluorescence thermometry; Core/shell quantum dots; Gas~phase; Adsorption dynamics