Max Planck researchers elucidate how the phase state of aerosol nanoparticles depends on their size
Whether tiny particles in the air, so-called aerosol nanoparticles, are solid or liquid, is of great importance to atmospheric and climate scientists. The phase state determines if and how fast such particles grow into cloud condensation nuclei on which water vapor can condense to form cloud droplets and precipitation.
Until recently, however, experimental observations of the solid-liquid phase transitions and humidity-dependent growth of atmospheric aerosol nanoparticles could not be explained by theoretical calculations and model predictions.
Scientists at the Max Planck Institute for Chemistry could now resolve the riddle. "The particle size is more important than we previously thought, "says Yafang Cheng, group leader at the institute in Mainz. "For example, salt particles can become liquid not only by increasing temperature or humidity, but also by reducing the particle size," says the lead author of a recent publication in Nature Communications.
The researchers around Yafang Cheng and Hang Su analyzed high precision measurement data on the hygroscopic growth of sodium chloride and ammonium sulfate nanoparticles exposed to varying relative humidity.
From these growth curves, the researchers calculated the interfacial energies and critical diameters for the solid-liquid phase transitions of the salt nanoparticles. According to similar analyses, the researchers expect that organic aerosol particles commonly occuring in large quantities in the atmosphere are always liquid at room temperature when their diameter is below approximately 20 nanometers.
"Based on our results the particle size should be considered as an additional dimension in the phase diagram of aerosol nanoparticles," says Cheng´s colleague Hang Su. “Our findings are also relevant for other research areas where nanoparticles play a role, including the biomedical and materials sciences.” For example, they may help to determine and control the solubility and concentration of therapeutic or reactive agents in in synthetic nanoparticles for medical or technical applications.
Cheng et al., Size dependence of phase transitions in aerosol nanoparticles, Nature Comm., 6, 2015, doi:10.1038/ncomms6923
Dr. Hang Su
Max Planck Institute for Chemistry
Dr. Susanne Benner | Max-Planck-Institut für Chemie
Rainbow colors reveal cell history: Uncovering β-cell heterogeneity
22.09.2017 | DFG-Forschungszentrum für Regenerative Therapien TU Dresden
The pyrenoid is a carbon-fixing liquid droplet
22.09.2017 | Max-Planck-Institut für Biochemie
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
22.09.2017 | Life Sciences
22.09.2017 | Medical Engineering
22.09.2017 | Physics and Astronomy