Real-space observation of ultrastrong coupling between optical phonons and surface plasmon polaritons

 

The physical and chemical properties of atoms and molecules are determined by their energy levels. If these levels can be controlled, it becomes possible to modify material properties, which has important applications in materials science, chemistry, and photonics.

A modern approach to achieving such control is based on the strong and ultrastrong coupling between light and matter. In this regime, energy is coherently exchanged between the two systems, giving rise to Rabi oscillations and to the formation of hybrid light–matter states known as polaritons. In this process, various excitations arising from light–matter interactions may participate, such as excitons, plasmons, phonons, and molecular vibrations.

In this work, researchers from Spain and France present a nano-spectroscopic technique based on nanoscale Fourier-transform infrared spectroscopy (nano-FTIR). This technique enables real-space mapping of the ultrastrong vibrational coupling between the optical phonons of a thin SiC layer and the surface plasmon polaritons of an InAs semiconductor substrate.

This ultrastrong coupling, which occurs when a system is photoexcited, takes place over a wide range of wave vectors and gives rise to a large number of hybrid modes (mixtures of light and matter). In particular, when light couples to molecular vibrations or to lattice vibrations (phonons), changes in chemical reactivity have been observed. This facilitates the study of polaritonic chemistry, in which light modifies the behavior of material systems, and may even lead to theoretically predicted phase transitions induced by strong and ultrastrong coupling.

These results are relevant for a wide range of applications, including ultrasensitive sensors, nonlinear optics, and quantum technologies.

For further information go to: Nature materials

Electrogenerated Excitons for Tuning Lanthanide Electroluminescence

 

At present, the most common sources of lighting come from modern photonic devices based on light-emitting diode (LED) technology, which converts electrical energy into photons by using the electroluminescence (EL) phenomenon of certain materials. Although major technological advances have been achieved, improving LEDs to obtain a broader color palette with more intense and vivid colors, increase their operational lifetime, and enable optimized production, poses a challenge with the use of conventional materials. One current strategy relies on using insulating nanoparticles that contain ions from the lanthanide group. As the periodic table shows, this group comprises 14 chemical elements from lanthanum to ytterbium.

Lanthanide-doped nanocrystals offer a fundamentally different approach to EL engineering. The 4f–4f transitions of lanthanides yield narrow emission lines (<10 nm bandwidth), with photochemical and thermal stability, long excited-state lifetimes, and defect-insensitive emission—features that are advantageous for spectrally precise and stable EL operation.

However, the insulating nature of these nanocrystals presents a challenge for charge transport and injection, hindering their application in electrically driven optoelectronic devices.

Researchers from China and Singapore demonstrated efficient EL by doping insulating (4 nm) NaGdF₄:X nanocrystals with X = Tb³⁺, Eu³⁺, or Nd³⁺, and coating them with a series of functionalized 2-(diphenylphosphoryl)benzoic acid ligands (ArPPOA). These ligands, composed of phosphine oxide groups with carboxyl and P=O coordination sites, exhibit hybrid donor–acceptor character that effectively sensitizes the luminescence of lanthanide nanocrystals by modulating charge transfer between ligands. Ultrafast spectroscopy studies revealed that the strong coupling between ArPPOA and the lanthanide nanocrystals facilitates sub-nanosecond intersystem crossing and highly efficient triplet-to-nanocrystal energy transfer (up to 96.7%). Through careful control of dopant composition and concentration within the nanocrystals, the researchers achieved broadband multicolor EL without altering the device architecture, reaching an external quantum efficiency above 5.9% for Tb³⁺.

This platform of functionalized nanocrystals provides a modular strategy for exciton (electron–hole pair) control in insulating nanocrystal systems, offering a route to electroluminescent materials with precise emission spectra.

This work was published in Nature

Additional information can be found in Nature

MOFs: From Their Origins to the Nobel Prize

 

The term metal organic frameworks (MOFS was coined by Omar M. Yaghi in 1994, who later became the leading figure in the field. However, it was Richard Robson who had already laid the conceptual foundations for these structures back in 1989.

Later, in 1997, Susumu Kitagawa demonstrated the practical functionality of MOFs by showing their ability to store methane. 

These pioneering works in the field led to the synthesis of tens of thousands of compounds with promising applications.

For these achievements, the 2025 Nobel Prize in Chemistry was awarded to Omar M. Yaghi, Richard Robson, and Susumu Kitagawain recognition of their major contributions to the discovery of metal–organic frameworks.

But what exactly are these frameworks, and what are they used for?

MOFs are materials in which metal ions or clusters are linked by organic molecules, forming a regular, repeating pattern that creates a three-dimensional network. A key feature of these materials is that large cavities form in the space between the metallic nodes and the organic linkers, making them highly porous. Yaghi once noted that just one gram of a MOF can have an internal surface area roughly equivalent to two American football fields.

MOFs possess unique properties such as high surface area, low density, high flexibility, and tunable pore functionality, which make them suitable for a wide range of applications.

For instance, due to their high porosity, MOFs have been studied for hydrogen and methane storage. MOF-177, for example, has been reported to store up to 7.5 wt% hydrogen. They have also been used for CO₂ capture and nitrogen adsorption.

The use of MOFs has expanded into the biomedical field, particularly for drug delivery. Compared with other materials, they offer several advantages: adjustable pore size, high drug-loading capacity, and the ability to functionalize pore surfaces. For example, the MOFs MIL-53(Fe) and MIL-53(Cr) have been shown to store up to 17.4% ibuprofen with a prolonged release time of 21 days.

Their application has also been explored in lithium-ion battery (LIB) electrodes. Commercial LIBs typically use graphite anodes, which have a maximum capacity of 372 mAh/g. In comparison, a composite material consisting of magnetite (Fe₃O₄) particles encapsulated by the MOF HKUST-1 demonstrated a capacity of 1001.5 mAh/g — higher than that of pure magnetite (696 mAh/g) and graphite.

MOFs exhibit exceptional properties and remarkable versatility, as evidenced by their use across a wide variety of fields and technological devices. The numerous advances in their study and development were, without a doubt, the reason behind this year’s Nobel Prize in Chemistry.

For more information: Chemistry Nobel Prize

Dielectric Constant and Conductivity of Planar-Confined Water

 

Water is essential for life, and its properties have been extensively studied, yet little is known about its electrical behavior under interfacial or extreme confinement conditions.

In such states, water loses its bulk structure and adopts a laminar

arrangement, modifying its electrical conductivity, polarizability, and

the intermolecular forces that govern numerous physical and chemical processes.

In this work, the in-plane dielectric properties of water confined between two hBN layers—one flat and one patterned with channels—separated by up to 1 nm, were measured.

Scanning Dielectric Microscopy (SDM), based on an Atomic Force Microscope (AFM), was employed to detect capacitance variations of the water confined within the channels formed on the hexagonal boron nitride (hBN) surface.

When the confinement exceeds several nanometers, the dielectric constant and conductivity of water approach their bulk values, and proton conduction increases. As the water layer thickness decreases, conductivity rises sharply, and when the thickness reaches only a few molecular layers, the in-plane dielectric constant attains values on the order of 1000—similar to those of ferroelectric materials—while conductivity reaches several S m⁻¹, comparable to that of superionic liquids.

Bulk water exhibits a high dielectric constant (ε_bulk ≈ 80) and a conductivity of approximately σ_bulk ≈ 10⁻⁵ S m⁻¹, values similar to those of a wide-bandgap semiconductor. This explains its ability to form hydrogen bonds and to dissolve more substances than any other liquid, producing strong dielectric screening essential for the biochemical processes of life.

Recent studies have shown that water confined between monolayers is

non-polarizable in the perpendicular direction (ε_⊥ ≈ 2), in agreement with theoretical predictions, although the parallel dielectric constant (ε_∥) remains experimentally unknown and theoretically unexplained.

This work demonstrates that under extreme molecular confinement, the electrical properties of 2D-confined water change dramatically, providing new insights into the electrical double layer and strongconfinement phenomena, and opening avenues for explaining interfacial and nanoconfined aqueousprocesses in other materials.

For further information see: Nature

Cat Video Made With Atoms

 

  

 

Quantum computing promises to solve problems that are impossible for classical computers. Instead of bits that can only be 0 or 1, quantum machines use qubits, which can exist in multiple states at once. This greatly increases computational power but also introduces major challenges: qubits are unstable and prone to errors.

Among the various platforms under development, Rydberg atom arrays stand out for their potential. In these systems, individual atoms are trapped using beams of light called optical tweezers. This technique offers high precision, allows flexible connections between atoms, and can be scaled up to very large systems. Thanks to these features, key steps toward quantum computing have already been demonstrated, including error correction and the simulation of complex physical phenomena.

A significant obstacle arises when loading atoms into the system: many positions in the array remain empty. To make full use of the system, the atoms must be rearranged to form a defect-free array. Traditional methods move atoms one by one, which is far too slow for systems containing thousands of particles.

The solution proposed by the cited research team combines artificial intelligence (AI) with a spatial light modulator (SLM). This device can modify a laser beam in real time and, guided by AI, shift all atoms in parallel toward their final positions. The process is divided into very small steps to minimize losses and errors.

Here is how it works: first, rubidium atoms are randomly loaded. A camera records their distribution, and a neural network identifies which sites are occupied. Then, the AI calculates the optimal route for each atom to move. Finally, the SLM generates light holograms that simultaneously guide all the atoms into their target positions, forming the desired array.

Using this technique, researchers succeeded in building the largest defect-free array ever reported: 2,024 perfectly ordered atoms. The paper shows a video of the famous Schroedinger cat made with atoms. This achievement brings us closer to more powerful quantum computers and opens the door to simulations of physical systems that are impossible to study with current technologies.

For further information and the Schroedinger Cat Video, see Phys. Rev. Letters

A new genomic editing strategy using lipid nanoparticles with spherical nucleic acids and CRISPR

 

CRISPR-Cas systems are a recently discovered biological tool that functions like “molecular scissors,” capable of locating and cutting specific fragments of DNA to modify or correct them with great precision. This gene-editing machinery has transformed biology by offering the possibility of correcting genetic errors.

However, one of its main challenges has been transporting the editing machinery safely and efficiently into cells, since traditional methods—such as viral vectors or lipid nanoparticles (LNPs)—often present issues like toxicity, low efficiency, or immune reactions.

A recent study proposes an innovative solution by encapsulating the CRISPR-Cas machinery inside lipid nanoparticles coated with spherical nucleic acids (SNAs), resulting in nanostructures of approximately 130 nm in size. The outer DNA layer facilitates entry into cells, while the lipid core stabilizes the CRISPR-Cas system and enables its controlled release. The lipid nanostructure includes both the plasmids that encode the CRISPR machinery, and the templates required for DNA repair by means of the HDR (homology-directed repair) pathway.

In summary, this design allows for improved cellular uptake of the nanoparticle, which in turn delivers the CRISPR-Cas machinery. It reduces toxicity and increases gene-editing efficiency.

The research team tested this strategy using different cell types and evaluating how many nanoparticles successfully entered the cells, if there were toxic effects, and whether the CRISPR machinery was effectively delivered. They then analyzed the cellular DNA to confirm if CRISPR had produced the expected edits.

The results showed that this system not only generated the typical nucleotide deletion edits but also enabled precise repairs by means of the HDR pathway. Compared with conventional LNPs, the new structures were more efficient, showed no toxicity, and maintained high cell viability even at elevated concentrations.

The researchers emphasized that these hybrid nanoparticles, called LNP-SNAs, could in the future be adapted to target specific organs. Thanks to their greater safety and efficacy, CRISPR-LNP-SNAs represent a versatile and scalable platform that brings gene-editing therapies closer to clinical application.

For further details, see: PNAS

Reconfigurable Ferroelectric Field-Effect Transistors with Single-Walled Carbon Nanotube Channels

 

The rapid development of the internet and artificial intelligence has accelerated data generation, imposing greater demands on data processing. To process data efficiently, it is necessary to reduce device dimensions and operating voltage, thereby lowering energy consumption.

However, with current field-effect transistor (FET) technology, such as silicon complementary metal-oxide-semiconductor (CMOS) transistors, these improvements have met with physical limitations: when transistors become too small, electrical control issues arise. More specifically, size reduction is hindered by effects associated with short channel length; while lowering the voltage below 1 V is constrained by the Boltzmann limit, which depends on the constant ratio between the interaction potential and the mean free path of charge carriers.

Considering these limitations, reconfigurable transistors—capable of changing their operation after fabrication—offer a promising alternative. A special case is reconfigurable FeFETs, which can operate as either p-type or n-type transistors as needed.

A research team from Korea, the U.S., and China developed this type of devices using highly aligned single-walled carbon nanotubes (SWCNTs) as semiconductor channels and an innovative ferroelectric material (aluminum–scandium nitride). These devices exhibit ambipolar carrier characteristics with high and well-balanced ON-state currents (~270 μA μm−1 at a drain voltage of 3 V) and ON/OFF ratios greater than 105, along with wide memory windows and excellent retention capability. Furthermore, they feature ternary memory capability (able to store -1, 0, or +1 instead of just 0 and 1). This means that more compact and efficient circuits can be built compared with those based on conventional silicon.

Further information in: Nature Communications