Ikerbasque researcher: Lucia Vitali
San Sebastian is internationally known for its contributions to quantum physics
Quantum phenomena at the nanoscale is a topic in your research career, could you explain what is it about?
Quantum physics is the most modern theory of physics: it has been formulated in the so called the “golden age” of physics at the beginning of last century. Its development was stimulated by experimental evidences achieved a few years before, which could not be explained by the “classical” physics. It was observed for example that shining light with a minimum energy on certain materials was causing the emission of electrons. These were unexpectedly emitted at well-defined discrete (“quantum” in Latin) energies, which varied according to the material considered.
It was clear that these observations were steering to a deeper understanding of the atomic structure matter. This, on turn, leaded to the formulation of a quantum theory, which constitutes in a very wide and comprehensive way the basis of modern physics including solid states physics, nuclear-, particle -, chemical- physics and optics. The success of quantum physics is due to its capability to explain and predict many features and observations of our world. Quantum phenomena are more clearly distinguishable as the dimensions of the solid considered are strongly reduced. At nanoscale matter is formed only by a bunch of atoms, and electrons are confined into very small dimensions and can have only well-defined discrete energy. As a consequence their physical and chemical properties (as electronic structure, electrical resistivity, chemical reactivity, but also transport of charge and heat, etc.) differ from the one at the macroscale. For instance, gold, which is one of the most inert metals at the macroscale, is very reactive and shows catalytic activity if nanoparticles formed by few atoms are considered. Many metal nanoparticles assume a different colour than in the macroscale, reflecting a “different” electronic structure. This causes, as explained by quantum physics, also the capability of gold nanoparticles to absorb a light frequency, which differs from the one adsorbed at the macroscale, and to show a different colour. Although they ignored the physical principle, glassblowers used metal-salt and oxides containing small metal particles already in the ancient time to produce coloured stainedglass for cathedrals. Well-defined colours were obtained adding, to the molten glass, metal nanoparticles, which absorbed specific light frequencies: copper oxides, cobalt and gold were added to obtain green, blue and red colored glass. Nowadays, much of the fascination with nanotechnology and possible applications in nanodevices stems from unique quantum and surface phenomena that matter exhibits at the nanoscale. Single atoms, molecules, small nanoparticles or new hybrid-systems that nanotechnology allows to synthetise are explored to create new functionalities for many new possible applications.
Quantum physics, nanoscale, nanotechnologies… how do you foresee the big picture of the future of material science?
While the formulation of the basic principles of quantum physics has occurred in the early 20 century, the technological capability necessary to synthetise and manipulate matter as well as to characterize it with sufficient control at nanoscale has been achieved only recently. Despite this, much of our today technology operates at scale where quantum physics and nanotechnology are more than significant. This includes devices and applications which are part of our day life as hard-disks storage devices, LED (also organic based), transistors, integrated circuits, catalysator, microwave ovens, conducting polymers, acceleration sensors in air bags, biocompatible materials ranging from artificial prothesis to contact lenses, sun-filter creams and cosmetics, magnetic resonance imaging in medicine, laser, etc.. These few examples demonstrate not only how wide the possible applications of nanotechnology can be, but also that it is a field in rapid expansion and improvements. The fundamental and applied research efforts are not only stimulated by the so-called trend in miniaturization (i.e. the demand of smaller and smaller functional units by the industry of integrated circuits) but also by the need to develop new functionalities or to improve the efficiency of the existing ones. In order to achieve this different strategies are usually applied: the so called “top-down” and the “bottom-up”. Following the first, nanoparticle or nanostructure are shaped from solid showing defined properties at macroscale. The second, instead, aims to the formation of complex structures obtained by assembly or self-assembly of smaller ones as single atoms and/or molecules. Many new functionalities are inspired by Nature: efficient energy conversion and corrosion protection can only be modelled from photosynthesis and hydrophobic surfaces in plants leaves. This underlines another one important aspects of nanotechnology and quantum science: its broad and interdisciplinary character both at applied and fundamental level. The large overlap between atomic and molecular physics, chemistry, material engineering, biology and biophysics as well as the theoretical and the experimental approach demands close cooperation between scientists operating on different fields. At present, quantum physics and nanotechnological applications focus on several research fields: environmental friendly science (catalysis, and new material for a cleaner energy production as organic solar cells, energy- or H-storage, protection coatings), information storage (nanomagnetisms, giant magneto-resistance, molecular magnets, spintronics) and information transmission (cryptography), medical care (functional pharmaceutical, new nanoparticle-based therapies as hyperthermia, chemical sensors, diagnostics), nano- and opto- electronics (signal generation and transmission and device applications, gas or chemical sensors, molecular-based electronics) are only a limited list of them. While for some of them possible applications in nanotechnology have already been demonstrated at least at research level, possibly some of the current investigated materials might not turn into nanotechnology in the immediate future. However, I do believe that the knowledge we are gaining through their investigations at fundamental level is an essential step towards our understanding of the “nanoscale” world.
What has it brought your decision to join ikerbasque to your career and in which way do you consider it as an important decision in your life?
The decision to come to San Sebastian and starting an independent research group was and is certainly a new challenge for me. However, when Ikerbasque offered me this interesting opportunity, I had no doubts and I was, with good reasons, delighted to accept. San Sebastian is, since long time, internationally known for its contributions to quantum physics and surface science at theoretical level. Additionally, this and the experimental research are now in further strong development: new institutes are open and brilliant scientists are attracted here. This provides excellent interdisciplinary surroundings to further develop science at nanoscale dimensions. Moreover, Ikerbasque offered not only a working place but contributed also to the instrumental infrastructure, which I have really appreciated as it facilitate the starting.
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