Scientific Highlights from Research Division Energy and Environment (ENE)

Scientific Highlights

5 September 2019

Kinetics and Mechanism of Metal Nanoparticle Growth via Optical Extinction Spectroscopy and Computational Modeling: The Curious Case of Colloidal Gold

An overarching computational framework unifying several optical theories to describe the temporal volution of gold nanoparticles (GNPs) during a seeded growth process is presented. To achieve this, we sed the inexpensive and widely available optical extinction spectroscopy, to obtain quantitative kinetic data. In situ spectra collected over a wide set of experimental conditions were regressed using the hysical model, calculating light extinction by ensembles of GNPs during the growth process. This model rovides temporal information on the size, shape, and concentration of the particles, and any electromagnetic interactions between them. Consequently, we were able to describe the mechanism of GNP growth and divide the process into distinct genesis periods. We provide explanations for several longstanding mysteries, e.g., the phenomena responsible for the purple-greyish hue during the early stages of GNP growth, the complex interactions between nucleation, growth and aggregation events, and a clear distinction between agglomeration and electromagnetic interactions. The presented theoretical formalism has been developed in a generic fashion so that it can readily be adapted to other nanoparticulate formation scenarios such as the genesis of various metal nanoparticles.

15 July 2019

Chemically mapping ice forming particles

Scientists have just nucleated ice in an X-ray microscope for the first time and they created chemical maps of those responsible.

23 October 2018

Breakthrough - electron crystallography for everyone

Recent advances in electron crystallography published in Angewandte Chemie and highlighted by Science, Chemical & Engineering News and ScienceNews!Under the lead of LSK member, "Rapid structure determination of microcrystalline molecular compounds using electron diffraction", published in Angewandte Chemie International Edition https://onlinelibrary.wiley.com/doi/abs/10.1002/anie.201811318 has attracted great attention in the chemistry community.

17 October 2018

Warum die Kleine Eiszeit Mitte des 19. Jahrhunderts endete

Medienmitteilungen Energie und Umwelt Umwelt

In der ersten Hälfte des 19. Jahrhunderts führte eine Serie grosser Vulkanausbrüche in den Tropen zu einer vorübergehenden globalen Abkühlung des Erdklimas. Dass in der Endphase dieser sogenannten Kleinen Eiszeit die Alpengletscher wuchsen und anschliessend wieder zurückgingen, war ein natürlicher Prozess. Dies haben nun PSI-Forschende anhand von Eisbohrkernen nachgewiesen.

29 June 2018

Brennstoffzellen zum Durchbruch verhelfen

Wasserstoff gilt als vielversprechende Alternative für eine Zukunft ohne fossile Energieträger. Um Brennstoffzellen weiterzuentwickeln und für einen Markteintritt vorzubereiten, verstärkt die Empa die Zusammenarbeit mit der H2 Energy Holding AG und dem Paul Scherrer Institut (PSI).

26 September 2017

In the experimental chamber, a very thin vertical jet of water can be seen, which flows downward in the middle of the picture from a small tube. During the experiment, the chamber contains a gas mixture including ozone, which reacts on the surface with bromide in the water and produces bromine. As an intermediate step in the process, a short-lived compound of bromide and ozone is made, which was detected for the first time ever with the help of X-ray light from SLS. For this proof, the X-ray light knocked …

Light from the particle accelerator helps to understand ozone decomposition

PSI researchers have developed an experimental chamber in which they can recreate atmospheric processes and probe them with unprecedented precision, using X-ray light from the Swiss Light Source SLS. In the initial experiments, they have studied the production of bromine, which plays an essential role in the decomposition of ozone in the lower layers of the atmosphere. In the future, the new experiment chamber will also be available for use by researchers from other scientific fields.

21 September 2017

Coexistence of Physisorbed and Solvated HCl at Warm Ice Surfaces

The interfacial ionization of strong acids is an essential factor of multiphase and heterogeneous chemistry in environmental science, cryospheric science, catalysis research and material science. Using Near Ambient Pressure X-ray Photoelectron (NAPP) spectroscopy, we directly detected a low surface coverage of adsorbed HCl at 253 K in both molecular and dissociated states and interpret the results as physisorbed molecular HCl at the outermost ice surface and dissociation occurring upon solvation deeper in the interfacial region. This study gives clear evidence for nonuniformity across the air−ice interface and questions the use of acid−base concepts in interfacial processes.

13 July 2017

Gasoline cars produce more carbonaceous particulate matter than modern filter-equipped diesel cars

In contrast to nitrogen oxides, modern gasoline cars emit much more cancerogenic primary soot (black carbon + primary organic aerosol) and lead to more toxic secondary organic aerosol than modern diesel vehicles.

22 February 2017

Ice-core evidence of earliest extensive copper metallurgy in the Andes 2700 years ago

Although copper (Cu) was essential for the wealth of pre- and post-colonial societies in the Andes, the onset of extensive Cu metallurgy in South America is still debated. Based on a 6500 year ice-core Cu record from Illimani glacier in Bolivia we provide the first complete history of large-scale Cu smelting activities in South America. Earliest anthropogenic Cu pollution was found during the Early Horizon period ~700-50 BC. We attribute the onset of intensified Cu smelting in South America to the activities of the central Andean Chiripa and Chavin cultures ~2700 years ago. This study provides for the first time substantial evidence for extensive Cu metallurgy already during these early cultures.

Secondary navigation