Nanostructures have an outstanding potential in several industrial applications, which has motivated to develop fast, easy and flexible methods for their fabrication. Laser irradiation of metal nanostructures such as thin films and nanoparticles induces melting and ablation, which allows the transformation of the nanostructures itself, and the structuration of the substrate below them. For...
We introduce an atomic gravimetric sequence using Raman-type composite light pulses that excites a superposition of two momentum states with the same internal level. The scheme allows the suppression of common noise, making it less sensitive to external fluctuations of electromagnetic fields. The Raman beams are generated with a fiber modulator and are capable of momentum transfer in opposite...
Real-time and multi-elemental analysis for online water monitoring is an important task towards environmental safety, public health, water purification control, the adequate reuse of wastewater, and for many processes in engineering and industrial fields. However, the online water monitoring cannot be performed by analytical conventional techniques (LA-ICP-MS, ICP-OES or XRF) because they...
Ballistic electrons in phosphorene pn junctions show optical-like phenomena. Phosphorene is modeled by a tight-binding Hamiltonian that describes its electronic structure at low energies, where the electrons behave in the armchair direction as massive Dirac fermions and in the orthogonal zigzag direction as Schrödinger electrons. Applying the continuum approximation, we derive the electron...
Photocatalysis is an emerging field in which the solar energy/visible light is utilized for different types of catalytic applications including elimination of contaminants from water, air, soil, water splitting mechanisms, sterilization etc. Metal oxide nanoparticles and its different categories like modified metal oxides, nanocomposites, hybrids etc. were used commonly for photocatalytic...
In the last 20 years the field of nanotechnology has grown extensively due to its surface, optical and magnetic properties. Among the different types of nanoparticles gold nanoparticles (Au-NPs) outstand due its optical properties, chemical surface and biocompatibility. Laser ablation in liquids (LAL) is a synthesis method that allow to obtain high purity gold nanoparticles in a variety of...
Three commercial brands of aluminum foil available in Mexico (Reinolds, Avilés, Great Value) are studied. In this work, we have obtained experimental results, which demonstrate that commercial aluminum foil enhances the Raman signal. The Raman signal enhancement of methylene blue at a concentration of 1x10-6 M has been analyzed by placing a drop (6 ul) onto samples of the three commercial...
In this work, a fast and efficient method for the synthesis of silver nanoparticles coated with silica by means of the laser ablation technique in combination with oxidation-reduction mechanisms in aqueous solution is presented. This method is a chemical synthesis where the reducer agent is introduced in nanometer form by laser ablation of a solid target submerged in an aqueous solution. In a...
In recent years, the use of thin films of metal chalcogenides has been increased in photovoltaic solar technology. Mainly, semiconductor materials such as Antimony Sulphide (Sb2S3) are used due to their high absorption coefficient and band gap (1.7-2.5 eV). However, Sb2S3 thin films obtained by chemical bath, the most common method of manufacturing them, have an absence of crystallinity,...
Irradiation with a single nanosecond laser pulse in the melting regime can result in a characteristic change in the surface morphology of crystalline silicon. This has been verified experimentally in a variety of situations. In certain irradiation conditions dimple-shaped surface topographies are produced. In this work the dimple height, depth and width are modelled following the approach of...
Polymer quantum mechanics constitutes a theoretical lab where some of the mathematical techniques used in Loop Quantum Cosmology and Loop Quantum Gravity can be tested or better understood. On the other hand, the canonical transformations are an essential tool of the Hamiltonian formalism at both, classical and quantum level. In this talk, I will discuss the unitary representation of the...
We report results obtained in a laser-ablation experiment using targets chilled down to 20 K. In a previous work, our co-workers found that by increasing the temperature of the target above room temperature the emission of the lines increased in proportion to the target’s temperature [1]. In the present work we applied the focused beam of a pulsed, nanosecond Nd:YAG laser on a metallic surface...
Silica aerogels are nanoporous lightweight materials the frame of which consists of an assembly of connected small cross-sections beam-like elements resulting from fused nanoparticles. This particular assembly additionally provides silica aerogel a very low elastic stiffness when compared to rigid silica structure of identical porosity. Therefore, when aerogel plates are clamped, they are...
The plasma diagnostic is an in-situ method to monitor the deposition processes that involve the generation of plasmas. The pulsed laser ablation (PLA) and magnetron sputtering (MS) are plasma-assisted deposition techniques. Their combination is known as hybrid technique and denoted as MS-PLA. This hybrid technique has been employed to prepare coatings and films with specific applications such...
A review of the tools taken from information theory and how they have been used to analyze quantum systems will be presented. Formulations of uncertainty relations in entropic terms will be discussed with emphasis on the behaviors in the position, momentum and phase-space representations. Statistical correlations between (among) particles will also be addressed
The unique properties of silver particles are strongly dependent on the size and shape of the nanoparticles, NPs [1]. Ablation synthesis in solution has some limitations in the size control of NPs. So, to have a uniform size distribution at the time of synthesizing the NPs in solution, either by chemical method [2] or by laser ablation [3], has been a problem that is difficult to solve. Among...
In this talk we will present a brief historical review about metallic films with arrays of ordered holes which present extraordinary optical transmission. Then, the transmission properties of thin gold, copper and silver films deposited on quartz by pulsed laser deposition are presented. Well before the deposited metal forms a continuous film, these metals form islands on the substrate, when...
The Landauer-Büttiker formalism establishes an equivalence between the electrical conduction through a device, e.g., a quantum dot, and the transmission. Guided by this analogy we perform transmission measurements through three-port microwave graphs with orthogonal, unitary, and symplectic symmetry, thus mimicking three-terminal voltage drop devices. One of the ports is placed as input and a...
We use a classical optics approach to obtain the Bloch functions for several one-dimensional photonic crystals. To accomplish this, we choose the amplitude and phase representation, which leads us to a new procedure. These Bloch functions are based on numerical solutions to the field's amplitude equation, letting the refractive index vary continuously and periodically along one direction. Band...
Currently there are a number of different methods for obtaining nanosized materials such as thermal oxidation, sol-gel method, solvothermal synthesis, among others. However, the laser ablation of solids in liquids (LASL) technique has acquired great importance due to its relatively low cost, also considered as a green technique because it does not generates by-products and extra chemicals are...
The common classification of the electronic phases (insulator, semiconductor, semimetal, and metal) of the matter is based on spectral properties. However, the discovery of the topological insulators (TI) added a new kind of classification based on topological information carried by the eigenstates of the system. A topological insulator is a material that behaves as an insulator in the bulk...
The synthesis of molybdenum oxide (MoOx) nanoparticles (NPs) by using the laser ablation of solids in liquids (LASL) technique and their oxidation process was investigated. S/TEM-EDX microscopy images were used to study the oxidation process of these type of NPs. We hypothesized that the NPs oxidation depends on size, particularly it was observed that the smaller the NP not only the more...
Bimetallic nanoparticles have interesting properties for optical, electronic, magnetic and chemical applications. Pulsed laser ablation in liquid is an effective synthesis method to develop nanoparticles of metals, semiconductors and ceramics. In this work, colloidal solutions of bimetallic nanoparticles of silver / gold (50/50) were obtained by ablation using a Nd:YAG laser of 532 nm...
Cooperative effects are at the center of interest in many systems in physics such as cold atomic clouds, light harvesting systems, and trapped ions. Cooperative effects such as Superradiance and Supertransfer induce enhanced energy transport efficiency and robustness to noise. In the first part of the talk we will review the role of Superradiance/Superabsorption in light-harvesting systems....
The laser ablation of solids in liquids (LASL) is a novel and growing route for the synthesis of nanomaterials. It is mainly based on two approximations: the laser ablation of solid targets and the laser fragmentation of suspended powders or micromaterials. In both, the laser, solvent and solid target and/or the suspended material can be tuned in order to reach the desired nanomaterials. In...
An analytic representation of the three-body potential for the ground state of the molecular ion $H^{++}_3$ in equilateral triangle configuration is presented. This representation is based on an adequate description of the two-body potential energy curve $V(R)$ for the diatomic molecule $H^+_2$. The accurate representation of $V(R)$ for $H^+_2$ is achieved by matching short and long distances...
Ultrafast laser inscription is a technique by which pulses from a femtosecond laser, are used to micro-structure the surface or the bulk of solid materials. One of the most interesting features of this kind of lasers is the high peak intensities that can be reached when the delivered pulses are tightly focused. The intensities are typically in the range of 1012 – 1015 W/cm2, which can easily...
The phrase “one measure for all men and all times” summarizes the ideal that would lead to the development of the International System of Units, SI. The evolution of the definitions of the SI units of measurement may be somehow considered as a series of approximations to such an ideal in which the units of measurement are invariant in time and space, immutable, and susceptible to equivalent...
