Freiburg 2024 – scientific programme

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MO: Fachverband Molekülphysik

MO 25: Novel Experimental Approaches

MO 25.2: Talk

Friday, March 15, 2024, 11:15–11:30, HS 3044

Characterizing temperature, charging and adsorption dynamics of single nanoparticles — •Björn Bastian, Sophia Leippe, Kleopatra Papagrigoriou, and Knut Asmis — Wilhelm-Ostwald-Institut, Linnéstraße 2, D-04103 Leipzig

Single nanoparticle (NP) techniques allow to probe intrinsic properties of nanoparticles, but typically rely on surface deposition. Instead, we develop the analysis of single NPs in the gas phase using a cryogenic radio-frequency ion trap and UV/Vis or IR action spectroscopy. Absorption is indirectly monitored using NP mass spectrometry (NPMS): the produced heat causes the loss of messenger atoms or molecules that are adsorbed to the particle surface. Here, we present current progress on controlling and characterizing the charge state, temperature and surface coverage of single trapped NPs that will ease the implementation and quantitative analysis of future experiments.

Inducing charge changes is crucial for absolute mass determination and facilitates control in long experiments (∼ days). Using a filament to emit electrons for electron attachment or charge transfer — mediated by different collision gases at different pressures — we demonstrate full control of the charge state of positively charged silica NPs.

Characterizing binding sites and energies is an important goal for NP characterization and essential for quantitative action spectroscopy. Extensive adsorption measurements on silica NPs are presented and we demonstrate in situ fluorescence thermometry for semiconductor quantum dots. We will report on the latest progress to simultaneously measure temperature and adsorption on single fluorescent nanoplatelets.

Keywords: Nano particle mass spectrometry (NPMS); Single nano particle action spectroscopy (SNAS); Charge transfer; Surface adsorption; Fluorescence thermometry