V001 / JSI

Accurate detection of volatile organic compounds at trace concentrations holds a great promise for future health, safety, and environmental applications. In a recent Nature Communications report, Aleksander Matavž from the Condensed Matter Physics Department, together with colleagues from KU Leuven, address this challenge by introducing kinetic selectivity achievable in nanoporous crystals into the domain of chemical sensing. Their sensors measure the diffusion characteristics of adsorbed gases, which can differ by orders of magnitude even for very similar compounds. As a result, a single kinetic sensor can distinguish and quantify gases at ppm concentrations, even in mixtures with high humidity—outperforming a state-of-the-art commercial electronic nose. In addition to its applicative and market potential, the developed method represents a powerful tool for studying diffusion in thin films over a wide concentration and temperature range.

The colleagues from Department of Gaseous Electronics at Jožef Stefan Institute developed a fast-processing micro-plasma method for producing a plasmonic metasurface densely packed with electromagnetic hotspots, based on vertically aligned Cu₂O/CuO nanosheets decorated with silver nanoparticles. This lithography-free scaffold enables surface-enhanced Raman scattering with detection limits in the low nanomolar range for fast-tracing of different explosives such as tetryl and HMX, outperforming many commercial sensors while ensuring reproducibility. The approach also uncovers laser-dependent shifts in vibrational modes that define the nanostructure, providing valuable input for machine-learning-based data processing. Because the plasma treatment requires only short processing and is scalable simultaneously, the technique paves the way for compact lab-on-chip devices. Such devices could identify trace explosives and hazardous chemicals on-site, offering robust, portable, data-driven tools for border security, forensic applications, and environmental monitoring. The research was published in the journal Small.

The journal Nature Reviews Physics has published a review article entitled “Platforms for the realization and characterization of Tomonaga–Luttinger liquids”. In the article, Assist. Prof. Dr. Martin Klanjšek from the Condensed Matter Physics Department at the Jožef Stefan Institute, together with an international group of collaborators, provides an overview of the field of physics that has developed over the past two decades based on the theoretical concept of the Tomonaga–Luttinger liquid. The concept describes the physics of interacting quantum particles in one dimension, where, compared to the more common case of three dimensions, the role of interactions is so strong that it leads to very unusual collective behavior, which is, however, entirely universal, applying equally to fermions, bosons, and anyons. The article demonstrates how this concept has proven successful in describing experimental results in such diverse systems as organic conductors, carbon nanotubes, quantum wires, topological edge states in quantum spin Hall insulators, Josephson junctions, Bose liquids in nanocapillaries, and quantum spin chains and ladders.

Researchers of the Department of Low and Medium Energy Physics at Jožef Stefan Institute: Janez Turnšek, Klemen Bučar, Andrej Mihelič, Špela Krušič and Matjaž Žitnik, report new experimental results in Physical Review Letters. Upon passage of intense resonant XUV light of the free-electron laser FERMI through millimeters thick helium gas at a few tens of millibars pressure, self-amplification of weak spontaneous decay from doubly excited state has been observed at the EIS-TIMEX beamline. Due to stimulated emission, the fraction of excited atoms emitting an XUV photon instead of an electron has significantly increased significantly. The effect of decay redirection together with the collimation of emitted light leads to 8 orders of magnitude larger number of XUV photons emitted in the forward direction. This result provides opportunity to test new theoretical models and encourages further research to improve the efficiency of XUV spectroscopy and contribute to the development of new coherent light sources at short wavelengths.