Visualizing charges

Visualizing the behaviour of charge carriers will benefit the design and functionality of semiconductor devices. This, which seems a great idea, seems equally unattainable. However, at Delft University of Technology (The Netherlands) they’re famous for not having any respect for seemingly unattainable challenges.

Jacob P. Hoogenboom et al. have developed a technique to visualize “fast bulk charge recombination and slow trapping”. These two competing processes involve fast free charges and slow, more stationary, trapped charges. The device, a Lock-in ultrafast scanning electron microscope has enabled, in a proof of concept, a deep analysis of trap states on GaAs surfaces. And as they conclude, this technique will allow the study of “carrier transport in and across heterojunctions, underneath nanostructured surfaces, or at edges or layer transitions in two-dimensional materials”.

This image we made under the close supervision of Mathijs Garming (first author of the paper), has been featured as the cover of The Journal of Physical Chemistry Letters.

Long live the Nucleobase!

Multiple medical and biological sensors and targeted drug delivery are based in the functionalization of nanoparticles (NPs) with biomolecules. The role of the NPs is to enhance the optical response of the target surroundings. But this enhancement comes with a huge risk: this same radiation can severily damage DNA or RNA producing mutations.

Johannes Feist (UAM) together with groups from the University of Modena and the University of Munich, have studied in which conditions these NPs can act as a protection for the biomolecules (in this case Uracil) while being effective in their sensing/therapeutic function. And importantly, the results proposed in their research can be easily implemented with the current nanophotonic technology.

This paper, published in the Journal of Physical Chemistry Letters, has been recognized with the cover we designed together with the supervision of Dr. Feist.

Optoelectronics: MoS2 on canvas.

If I understand it correctly (and I’m probably not), Andres Castellanos is not only making interesting discoveries in condensed matter physics. He and his collaborators (Kavli Institute of Nanoscience and the University of Teheran) are also actively working on making it easier for others to make advances on this area. How? By making easier to use, cheaper technology.

A good example is their “under 100 bucks probe station”. Another one is this recent paper where they fabricate paper-supported semiconducting devices by painting on them with MoS2 crystal. Let me repeat this last statement: BY PAINTING ON THEM WITH MoS2. They’ve not only proved this methodology works and produces perfectly working devices. They also show how this approach could open the path for the construction of cheaper sensors.

The picture we did for them to illustrate this process has been featured in the cover of Nanoscale.

Hedgehog spin textures

Magnetic skirmions are quasiparticles which present extended configurations (or textures) of spins and their physics are of great interest since they could be used in spintronics as sensors or memory storage devices. Its manipulation and tailoring is thus of great importance.

In a recent work published in Nanoscale, a group led by Prof. Agustina Asenjo, report the stabilization of half hedgehog skyrmionic configuration in permalloy hemispherical nanodots, induced by the stray field of the MFM probe.

As the first author, Eider Berganza, explains, “this is a remarkable achievement due to soft magnetic nature of the permalloy and the absence of the choice of the material, which does not present magnetocrystalline anisotropy or Dzyaloshinskii–Moriya interaction, considered as necessary ingredients for the nucleation of skyrmions”.

 

This research, has been a huge collaborative effort that involved sample preparation, measurements and theoretical micromagnetic simulations in Spain, Germany and the US.

This image we did under the supervision of Eider Berganza and Miriam Jaafar (ICMM-CSIC) has been featured in the Cover of Nanoscale. Personally, has been the apex of a long and beautiful collaboration with old friends.

 

Polariton condensates’ propagation.

Polaritons are versatile quasiparticles that could be at the core of new technologies, since polariton devices have been proposed, such as polariton lasers, optical gates, transistors, spin-based elements and integrated circuits. Yet, their propagation depends strongly on the geometry of the pathway laid for them.

In a recent paper, Luis Viña, Dolores Martín, et al. in a huge collaborative research (Madrid, Jena, Würzburg, Saint-Petersburg, Reykjavik and Saint Andrews) have analyzed the Impact of the energetic landscape on polariton condensates’ propagation along a coupler”, published in Advanced Optical Materials.



The amount of technical challenges involved in this research is hard to grasp: from the manufacture of the guides to the experimental measurements, that require literally “taking pictures of light”.

We did this picture that was featured in the cover of Advanced Optical Materials, under close supervision of Dolores Martín and Luis Viña.

 

Sound Vortices

At Phonometa (Christensen’s Research Group), they’re specialists in physical acoustics and they’re finding acoustic analogues to an amount of physical processes.

In their last published work they show that, in Dr. Christensen own words “a Majorana‐like bound state can be engineered in artificial acoustic lattices thanks to a Jackiw–Rossi vortex, which is the analog of a topological superconductor vortex. Such vortex is created by introducing a Kekulé texture to the man‐made lattice of rigid cylinders. We also show how this binding mechanism can be well explained by a topological pumping process comprising adiabatic variations of the cylinder radii, which concentrates strong acoustic energy to the lattice center as shown in the cover image”.

This picture we made to illustrate the process, and under close collaboration with Dr. Johan Christensen and Dr Penglin Gao, was featured in the front cover of Advanced Quantum Technologies.

Covalent organic frameworks

Covalent organic networks are usually synthesized on noble metal surfaces. It is widely understood that these metals have strong catalytic abilities. However, it is of great interest the use of nonmetallic surfaces in these kind of reactions.

At the NanoPhysics Lab (CMF, Gipuzkoa) they’re studying one of these routes to obtain covalent molecular systems on non-metallic substrates. In particular they’ve managed to understand and improve the synthesis of nanoribbons on TiO2 surfaces. They show that highly reduced surfaces (in opposition to stoichiometric TiO2) increases the reaction yield and improved polymer length.

We did this picture to artistically illustrate the process under the close supervision of Dr. Celia Rogero.

Graphene Design

The level of control chemistry is reaching in the synthesis of graphene is mind-blowing. At the Department of Physics in Basel University, together with the University of Bern, Warwick and Lancaster, nitrogen-doped porous graphene nanoribbons (N-GNRs) were synthesized for the first time.

These N-GNRs are ladder-like molecules whose crystal lattice contains both periodic pores and a regular pattern of nitrogen atoms. And interestingly, these molecules don’t behave as conductors, as graphene does, but as semiconductors, making them very attractive in electronic applications.

We did this picture to illustrate the synthesis of the N-GNRs on request of Prof. E. Meyer and under the close supervision of Dr. Shi-Xia Liu.

 

On circulenes, flatness and butterflies.

Circulene is a polycyclic aromatic hydrocarbon molecule composed by eight benzene rings. Because of geometric demands, the molecule adopts a saddle-shaped structure.This family of molecules, made of hexagonal and pentagonal rings are been studied for their promising applications in organic semiconductors, organic light-emitting diodes and liquid crystalline materials.

Prof. Shingo Ito et al. have just described the first example of a circulene bearing six hexagons and two pentagons which happens to have unique electronic structures, and intrinsic properties. In particular, they’ve proved this circulene to adopt a planar configuration.

This research, published in the Journal of American Chemical Society (JACS), was featured on the cover. The image was made under close supervision of Prof. Shigeky Kawai and Prof. Shingo Ito.

 

Glowing Lanthanides

It’s not the first time we bring these people to our website, and there are several reasons for that. First of all, they keep hiring us to make cool images for them. But the main reason is that they are doing amazing work in the field of chemical sensors.

These time Dr. Juan Cabanillas-Gonzalez and Dr. Jose Sanchez Costa, both at IMDEA Nanociencia (Spain) bring us “A novel gas sensing mechanism exploiting lanthanide luminescence modulation upon NO2 adsorption”. To make a long story short, this is a crystal that glows beautifully when NO2 is around.

This has not only useful practical applications in the detection of NO2 market; it would make a beautiful luminescence displays without requiring expensive electronics. “But it also provides understanding of the nature and effects of NO2 interactions within the MOFs and the signal transduction mechanism.” You can read more about it in their recent article.

The picture we did to illustrate this experiment was featured on the cover of the Journal of Physical Chemistry Letters.