laser pulses to “clone” gold nanoparticles

Researchers and students from the Institute of Nuclear Fusion at UPM participate in a paper published in the journal Science, which shows that a solution with nanorods modified by ultrashort laser pulses has an optical quality never seen before.

Researchers and students from Universidad Politécnica de Madrid (UPM) / Institute of Nuclear Fusion, located in the Higher Technical School of Industrial Engineers, participate in a study that reports the use of ultra-short laser pulses to mold gold nanorods in aqueous solution. The work shows that the solution with the modified particles has an optical quality never seen before. The study was published on November 3rd, 2017 in the journal Science.

Applications of metal nanoparticles are based on their ability to absorb and reflect very efficiently the light of certain colors. These effects, called plasmonic, generate completely new optical properties, which cannot be obtained with structures of larger dimensions. These properties can be exploited for an incredibly large number of useful applications, which in many cases were not possible until now.

In medicine, for instance, you can take advantage of the light reflected by these particles to diagnose diseases and its absorption can be used to heat a very small volume and treat tumors in a localized manner and minimizing the typical side effects of conventional treatments. These plasmonic particles have also found applications in areas such as information technologies, energy production or environmental pollution control, among others.

In this work, gold nanorods were prepared using wet-chemistry methods, but the really revolutionary concept is the application of ultrashort laser pulses for the modulation of the geometry of the particles and the improvement of their optical properties. Likewise, standard characterization techniques (spectroscopy and electron microscopy), together with new theoretical models and advanced computer simulations have been used to understand the chemical and physical nature of the molding process. Most of these simulations were carried outat UPM, taking advantage of the infrastructure provided by CESVIMA.

According to Ovidio Peña Rodríguez, UPM researcher, “the manufacture of optically identical particles and the understanding of the underlying processes represents a change in mentality that can open new avenues for the development of nanomaterials with improved properties and applications”. “The study of the modification of materials under irradiation is a very important issue for our Institute”, adds José Manuel Perlado, Director of the Institute of Nuclear Fusion.

However, this research goes beyond using lasers pulses like a chisel in the hands of a sculptor to obtain the record of optical quality, where billions of gold nanorods behave as one. According to Antonio Rivera, an UPM researcher, “the study also provides the physical and chemical keys necessary to understand and control the process that leads to perfect nanomaterials from a point of view of their optical properties”.

In addition to Ovidio Peña Rodríguez, and the UPM professor Antonio Rivera de Mena, also participated in this work researchers from Universidad Complutense de Madrid (Andrés Guerrero Martínez, Luis González Macdowell, Mauricio Alcolea Palafox, Gloria Tardajos, Luis Bañares and Jesús González Izquierdo) and CIC biomaGUNE in San Sebastián (Luis Liz Marzán). PhD students Pablo Díaz Núñez and Alejandro Prada (UPM), Guillermo González Rubio (UCM and CIC biomaGUNE) and Pablo Llombart (UCM) also made important contributions. For this research has been essential the infrastructures of the Supercomputing and Visualization Center of Madrid (CESVIMA-UPM), the CIC biomaGUNE and the Ultra-Fast Laser Center (UCM).

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