Jaime Colchero- PhD
- Professor (Full) at University of Murcia
Jaime Colchero
- PhD
- Professor (Full) at University of Murcia
About
146
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Introduction
I am group leader of the research group “Devices, Investigation and Applications in Nanoscience” (DIANA) at the Centre for Optics and Nanoscience of the Universidad de Murcia. My research focuses on Nanoscience, in particular Atomic Force Microscopy (AFM) and its application to fundamental processes at small scale: intermolecular forces, dissipation and noise in nanoscale systems, Nanotribology, nanoscale wetting of surfaces, investigation of biophysical systems as well as the electronic and morphological properties of polymers and molecular materials.
An important effort of my research has been the development of new instrumentation and new measurement techniques in the field of Scanning Probe Microscopy, including static and dynamic friction microscopy and low oscillation (non-contact) Dynamic AFM. I have an internationally recognized expertise in Electrostatic and Kelvin Force Microscopy, as well as in dynamic AFM in ambient environments, and in different aspects of multifrequency AFM. More recently, my research has focused also towards the combination of AFM with other nanoscale characterization techniques such as Syncrotron Radiation, Neutron Scattering as well as optical microscopy and spectroscopy, in particular Raman Scattering.
I hold 4 patents related to AFM, and am co-author of the WSXM software ( WSxM : http://wsxm.eu ) and co-founder of Nanotec Electronica (SPM/AFM instrumentation and software). Up to now, I have supervised 9 PhD thesis (8 finished, 1 in progress) and 6 master/diploma theses.
Current institution
Publications
Publications (146)
La variedad de las superficies vegetales es un tesoro biológico aún por explorar. Si la ciencia imita la naturaleza, hay todo un campo en el que apenas se ha mirado: el haz y el envés de las hojas de las plantas. Pero empezamos a asomarnos. Muchos seres vivos poseen pelos de diferente composición y estructura, y entre los seres vivos con pelo tambi...
Improving velocity forecasts of blood microflows could be useful in biomedical applications. We focus on estimating the velocity of the blood in capillaries. Modeling blood microflow in capillaries is a complex process. In this paper, we use artificial intelligence techniques for this modeling: more precisely, artificial neural networks (ANNs). The...
Many biological surfaces have hairs, known as trichomes in plants. Here, the wettability and macro-and micro-scale features of olive leaves are analyzed. The upper leaf side has few trichomes, while the lower side has a high trichome density. By combining different techniques including electron and atomic force microscopy, trichome surfaces are fou...
Nanoparticles (NPs) of conjugated polymers in intimate contact with sheets of graphene oxide (GO) constitute a promising class of water-dispersible nanohybrid materials of increased interest for the design of sustainable and improved optoelectronic thin-film devices, revealing properties exclusively pre-established upon their liquid-phase synthesis...
Conductive polymers have fundamental relevance as well as novel technological applications in the organic optoelectronics field. Their photophysical and transport properties strongly depend on the molecular arrangement, and nanoscale characterization is needed to fully understand the optoelectronic processes taking place in organic devices. In this...
Hace décadas que expertos en ciencia de materiales de todo el mundo tratan de dar respuesta a un bellísimo fenómeno de la naturaleza: el modo en que las esféricas gotitas de rocío se adhieren a los pétalos de la flor más popular del mundo, y no se caen, aunque pongamos la flor boca abajo. Este fenómeno recibe el nombre de efecto pétalo de rosa. Enc...
Graphene oxide (GO) is widely used as a component in thin film optoelectronic device structures for practical reasons because its electronic and optical properties can be controlled. Progress critically depends on elucidating the nanoscale electronic structure of GO. However, direct experimental access is challenging because of its disordered and n...
Rose petals can involve high water contact angles together with drop adhesion which are antagonistic wetting properties. Petal surfaces have a cuticle, a layer that is generally considered a continuous, hydrophobic lipid coating. The peculiar properties of rose petals are not fully understood and have only been associated with high surface roughnes...
We present a study of the effect of gold nanoparticles (Au NPs) on TiO2 on charge generation and trapping during illumination with photons of energy larger than the substrate band gap. We used a novel characterization technique, photoassisted Kelvin probe force microscopy, to study the process at the single Au NP level. We found that the photoinduc...
Two-dimensional materials, in particular graphene, exhibit a low friction coefficient and good wear properties. However, the tribological properties of these materials strongly depend on faint differences at the atomic level, and the coexistence of different type of atomic defects in studied samples up to date led to experimental results difficult...
Computational electrodynamics modelling plays an important role in understanding and designing new photonic devices. The results offered by these simulations are usually close-range field distributions or angular power emission plots. We describe a procedure to compute the optical microscopy image from simulated far-field scattering data using thre...
The performance of organic thin film optoelectronic devices strongly relies on the nanoscale aggregate structure of the employed conjugated polymer. Their impact on electronic interface interactions with adjacent layers of graphene, widely reported to improve the device characteristics, yet remains an open issue, which needs to be addressed by an a...
Under ambient conditions, surfaces are rapidly modified and contaminated by absorbance of molecules and a variety of nanoparticles that drastically change their chemical and physical properties. The atomic force microscope tip–sample system can be considered a model system for investigating a variety of nanoscale phenomena. In the present work we u...
In eukaryotes, the formation of a 5′-cap and 3′-poly(A) dependent protein–protein bridge is required for translation of its mRNAs. In contrast, several plant virus RNA genomes lack both of these mRNA features, but instead have a 3′-CITE (for cap-independent translation enhancer), a RNA element present in their 3′-untranslated region that recruits t...
Atomic force microscopy is based on tip sample interaction, which is determined by the properties of tip and sample. Unfortunately, in particular in ambient conditions the tip as well as the sample are contaminated, and it is not clear how this contamination may affect data in Atomic Force Microscopy (AFM) applications. In the present work we propo...
We have used the Scanning Kelvin probe microscopy technique to monitor the charging process of highly resistive granular thin films. The sample is connected to two leads and is separated by an insulator layer from a gate electrode. When a gate voltage is applied, charges enter from the leads and rearrange across the sample. We find very slow proces...
We have used the Scanning Kelvin probe microscopy technique to monitor the charging process of highly resistive granular thin films. The sample is connected to two leads and is separated by an insulator layer from a gate electrode. When a gate voltage is applied, charges enter from the leads and rearrange across the sample. We find very slow proces...
The present work analyses how the tip-sample interaction signals critically determine the operation of an Atomic Force Microscope (AFM) set-up immersed in liquid. On heterogeneous samples, the conservative tip-sample interaction may vary significantly from point to point - in particular from attractive to repulsive - rendering correct feedback very...
In this work, we propose an intuitive and easily implementable approach to model and interpret scanning Kelvin probe microscopy images of insulating samples with localized charges. The method, based on the image charges method, has been validated by a systematic comparison of its predictions with experimental measurements performed on charge domain...
Here we present the Mendeleev-Meyer Force Project which aims at tabulating all materials and substances in a fashion similar to the periodic table. The goal is to group and tabulate substances using nanoscale force footprints rather than atomic number or electronic configuration as in the periodic table. The process is divided into: (1) acquiring n...
Kelvin probe force microscopy in darkness and under illumination is reported in order to provide nanoscale-resolved surface photovoltage maps of hybrid materials. In particular, nanoscale charge injection and charge recombination mechanisms occurring in ZnO polycrystalline surfaces functionalized with Protoporphyrin IX (H2PPIX) are analyzed. Local...
The surface potential of conducting polymers has been studied with scanning Kelvin probe microscopy. The results show that this technique can become an excellent tool to really ‘see’ interesting surface charge interaction effects at the nanoscale. The electron glass model, which assumes that charges are localized by the disorder and that interactio...
In this work we demonstrate the capabilities of atomic force microscopies (AFMs) for the non-destructive determination of the polarity of GaN nanowires (NWs). Three complementary AFMs are analyzed here: Kelvin probe force microscopy (KPFM), light-assisted KPFM, and piezo-force microscopy (PFM). These techniques allow to assess the polarity of indiv...
The growth selectivity and structural quality of GaN nanowires obtained by plasma-assisted molecular beam epitaxy on pre-patterned GaN(0001) templates are investigated by means of non-destructive techniques. Optimum control over the nanowire arrangement and size requires a pitch between the mask apertures below twice the diffusion length of Ga atom...
We experimentally investigate the influence of AlN buffer growth on the nucleation and the polarity of a self-organized assembly of GaN nanowires (NWs) grown on Si. Two complementary growth mechanisms for AlN buffer deposited on Si are demonstrated. Both emphasize the aggregation of Si on the AlN surface and the growth of large cubic crystallites,...
Summary: Scanning Probe Microscopy (SPM) is already a relevant tool in biological research at the nanoscale. We present “Flatten plus”, a recent and helpful implementation in the well-known WSxM free software package. “Flatten plus” allows reducing low frequency noise in SPM images in a semi-automated way preventing the appearance of typical artifa...
A systematic study on the thin film morphology of heteroacenic derivatives such as indolo[2,3-a]carbazole and 11,12-dioctylindolo[2,3-a]carbazole has been carried out using scanning force microscopy and optical microscopy techniques. The investigation has comprised the preparation of a series of thin films by combining different solvents (dimethylf...
In this work the weathering phenomenon of building stones has been studied on the nanoscale. Red Quipar limestone samples have been exposed to ultraviolet (UV) radiation and acid attack and have been analysed by Scanning Force Microscopy (SFM) as well as optical measurements. The morphology of the samples along each step of the process has been cha...
In this work, we report a Kelvin probe microscopy investigation on the structural and electronic properties of gold and aluminum thin films evaporated on poly(3-octyl-thiophene) films. Our experimental setup allows us to perform scanning force microscopy (SFM) studies of the same area even if the sample is taken out of the SFM system for different...
The electro-optical properties of Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) thin films have been studied while the sample is illuminated with blue light. By combining Kelvin probe microscopy with classical optical techniques it has been possible to monitor the evolution of the nanoscale contact potential, the surface photo...
Scanning force microscopy and near-edge X-ray absorption spectroscopy are used to study the attachment of Protoporphyrin IX dye molecules to the low-index single-crystal faces of ZnO, namely, the polar (0001̅)
face and the nonpolar (101̅0) face. We found that surface etching depends on the crystal face for various dye immobilization procedures: whe...
The changes in morphology and electronic properties of Poly-3-octyl-thiophene (P3OT) thin films produced by UV/ozone exposure have been studied using Scanning Force Microscopy techniques. The layered structures associated to crystalline P3OT domains on the polymer film show a better resilience to the degradation than the amorphous polymer backgroun...
A method to precisely calibrate the oscillation amplitude in dynamic scanning force microscopy is described. It is shown that the typical electronics used to process the dynamic motion of the cantilever can be adjusted to transfer the thermal noise of the cantilever motion from its resonance frequency to a much lower frequency within the typical ba...
In this work we describe two simple and compact submicrometer-precision sample holders that are easily integrated into a Scanning Force Microscopy (SFM) system. The designs are based on a traditional kinematic mounting or on self-adjustment of the sample holder and the upper piece of the piezoelectric scanner. With these sample holders the sample p...
Scanning Probe Microscopy allows for extreme resolution down to the atomic
scale. Unfortunately, total scanning range is rather limited, therefore finding
a specific position on the sample is tedious. This is an important limitation
of many Scanning Probe Microscopes, in particular when the sample has to be
removed for some kind of treatment and th...
The wavelength dependence of the nanoscale light induced processes taking place in MEH-PPV/TCBM blended thin film samples has been studied by means of Kelvin probe microscopy implemented with controlled external sample illumination. First, both materials have been characterized individually and then these results have been used to explain the behav...
In this study, we show that the correct determination of surface morphology using scanning force microscopy (SFM) imaging and power spectral density (PSD) analysis of the surface roughness is an extremely demanding task that is easily affected by experimental parameters such as scan speed and feedback parameters. We present examples were the measur...
A study of the molecular structure of regio-regular bulk poly-3-octyl-thiophene (P3OT) and poly-3-hexyl-thiophene (P3HT) and the phase transitions during heating and cooling scans in a temperature range of –158–773 °C has been performed by means of calorimetry of bulk samples and grazing incidence X-ray diffraction from synchrotron radiation. Addit...
This paper describes a new strategy to obtain PEDOT/Au-nanorods nanocomposites with different PEDOT: Au ratio. A polymeric ionic liquid (PIL) was used as stabilizer during the chemical synthesis of PEDOT dispersions. PEDOT/Au-nanorods dispersions in organic media were obtained. Electrochemical characterization of PEDOT/Au-nanorods nanocomposites re...
Kelvin probe microscopy implemented with controlled sample illumination is used to study nanoscale surface photovoltage effects. With this objective a two trace method, where each scanning line is measured with and without external illumination, is proposed. This methodology allows a direct comparison of the contact potential images acquired in dar...
In this work variable temperature scanning force microscopy techniques have been used to study poly(3-octylthiophene) (P3OT) thin film samples. Topography images in combination with scanning force spectroscopy have been applied to characterize the morphology and mechanical properties of the P3OT surface. It has been found that at room temperature l...
The modification of the nanoscale morphology and electronic behavior as well as the mesoscopic optical properties of thin films of poly-3-octyl-thiophene (P3OT) has been studied as these films are irradiated by ultraviolet light (UV). Films of about 100nm thickness were prepared by spin-casting a P3OT solution in toluene on glass substrates. The sa...
The use of conducting polymers in optoelectronic devices is subject to the understanding of the electro-optical processes that take place at the nanoscale. One of the photo-induced processes that limit their application is the photodegradation, which reduces the device working life. In this work the photodegradation of poly(3-octylthiophene) thin f...
The modification of the conductivity as well as the nanoscale morphology and electrostatic properties of poly-3-octyl-thiophene (P3OT) thin films have been studied as these films are irradiated by ultraviolet light (UV). Films of about 100 nm thickness were prepared by spin-coating a P3OT solution in toluene on glass substrates. The samples were ch...
In the present work we show that the correct determination of surface morphology using Scanning Force Microscopy (SFM) imaging and Power Spectral Density (PSD) analysis of the surface roughness is an extremely demanding task that is easily affected by experimental parameters such as scan speed and feedback parameters. We present examples were the m...
Thermal fluctuation of the cantilever position sets a fundamental limit for the precision of any scanning force microscope. In the present work we analyze how these fluctuations limit the determination of the resonance frequency of the tip-sample system. The basic principles of frequency detection in dynamic scanning force microscopy are revised an...
Thermal fluctuation of the cantilever position sets a fundamental limit for the precision of any Scanning Force Microscope. In the present work we analyse how these fluctuations limit the determination of the resonance frequency of the tip-sample system. The basic principles of frequency detection in Dynamic Scanning Force Microscopy are revised an...
The present work proves that when non-contact Dynamic Scanning Force Microscopy (DSFM) is performed in ambient conditions wrong height measurements of heterogeneous samples can be obtained. In some extreme cases even contrast inversion can be observed. Alkanethiol islands on Au (111) have been used as model system, where contrast inversion is obser...
ZnO thin films grown by metal–organic vapor phase epitaxy along the nonpolar direction and exhibiting semipolar facets have been chemically etched with HCl. In order to get an insight into the influence
of the ZnO wurtzite structure in the chemical reactivity of the material, Kelvin
probe microscopy and convergent beam electron diffraction have bee...
Frequency modulation dynamic scanning force microscopy has been implemented in ambient conditions using low oscillation amplitudes (<1 nm) to simultaneously record not only topographic but also additional channels of information, in particular contact potential images. The performance of this mode as compared to the conventional amplitude modulatio...
The morphology and mechanical properties of poly-(3-octylthiophene) P3OT films thin has been studied by scanning force microscopy techniques. On these films we find self-assembled layered structures that appear regardless of the preparation conditions, that is, spin-coating or drop-casting, of the solvent concentration or of the type of substrate....
In this work the electrostatic properties of poly(3-octylthiophene) thin films have been studied on a nanometer scale by means of electrostatic force microscopy and Kelvin probe microscopy (KPM). The KPM images reveal that different surface contact potential domains coexist on the polymer surface. This result, together with additional capacitance m...
In this paper, the electrical transport and mechanical properties of Pt/ZnO Schottky nanocontacts have been studied simultaneously during the formation and rupture of the nanocontacts. By combining multidimensional conducting scanning force spectroscopy with appropriated data processing, the physical relevant parameters (the ideality factor, the Sc...
In this paper scanning force microscopy is combined with simple but powerful data processing to determine quantitatively, on a sub-micrometer scale, the orientation of surface facets present on crystalline materials. A high-quality scanning force topography image is used to determine an angular histogram of the surface normal at each image point. I...
We have studied blends of poly-(3-octylthiophene) (P3OT) and graphitic nanoparticles by macroscopic transport measurements, Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD) and Scanning Force Microscopy (SFM) techniques. Their morphology as well as their mechanical and electrical properties have been characterized on a nanometer scal...
In this work we briefly describe the most relevant features of WSXM, a freeware scanning probe microscopy software based on MS-Windows. The article is structured in three different sections: The introduction is a perspective on the importance of software on scanning probe microscopy. The second section is devoted to describe the general structure o...
Scanning force microscopy related techniques are applied to study surface nanoscale properties. We show that nanogoniometry
can be combined with local electrostatic measurements – electrostatic force microscopy and Kelvin probe microscopy – to identify
surface planes families and to study their local electrical properties. The scanning force micros...
Quantitative characterization of tip–sample interaction in scanning force microscopy is fundamental for optimum image acquisition as well as data interpretation. In this work we discuss how to characterize the electrostatic and van der Waals contribution to tip–sample interaction in non-contact scanning force microscopy precisely. The spectroscopic...
Mixtures of poly(3-octylthiophene) (P3OT) with graphite nanoparticles have been investigated by scanning force microscopy (SFM) techniques. The morphology as well as the mechanical and electrical properties of the blends has been characterized at the nanoscale level as a function of the carbon nanoparticle content in the blend. An increase in the c...
ZnO thin films have been grown along the nonpolar [10 1 0] direction by metal organic vapor phase epitaxy. The ZnO (10 1 0) surface develops well defined facets. The orientation of the topographic normals reveals that the inclination angle of the facets increases as thicker films are considered, attaining a maximum value of about 28.4°. This angle...
The surface electrical properties of ZnO thin films grown along the nonpolar [1120] direction have been investigated by Kelvin probe microscopy on a nanometer scale. Two different charge domains, with a 75 meV work function difference, coexist within the ZnO surface, which is covered by rhombohedral pyramids whose sidewalls are shown to be {1011}-t...
Locally resolved electrostatic force spectroscopy is combined with Kelvin force microscopy to compare the results obtained using either the force or the frequency as signal source for tip-sample interaction. A two-component locally heterogeneous sample-islands of octadecanethiol molecules self-assembled on Au(111)-is used as a nanometer scale model...
Alzheimer paired helical filaments (PHF) have been investigated with atomic force microscopy (AFM) under physiological conditions. Dynamic mode (DM) and jumping mode (JM) AFM have been employed as imaging techniques. Data obtained in solution have been compared to data obtained in ambient air with DM. In liquids, PHF particles show distortion and i...
The capabilities of the atomic force microscope for imaging biomolecules under physiological conditions has been systematically investigated. Contact, dynamic, and jumping modes have been applied to four different biological systems: DNA, purple membrane, Alzheimer paired helical filaments, and the bacteriophage phi29. These samples have been selec...
The measured height of DNA molecules adsorbed on a mica substrate by scanning probe microscopy is always less than the theoretical diameter. In this paper we show that, when imaged in ambient conditions, the molecules are usually immersed in the salt layer used to adsorb them to the substrate. This layer distorts the measurement of DNA height and i...
We have studied the interaction forces and electrical conduction properties arising between multiwall carbon nanotube tips and the Au(111) surface in air, by means of amplitude modulation scanning force microscopy, also called intermittent contact. We have centered our work on tips with metallic electronic structure and for the specific parameters...
In this work, we introduce jumping mode (JM) scanning force microscopy (SFM) as a suitable technique for imaging soft samples in liquid environment like DNA adsorbed on mica. JM reveals as a non-intrusive technique where shear forces are minimized by performing the scanning motion without tip–sample contact. We find no visible damage on DNA samples...
In the present work the electrostatic interaction of a real scanning force microscopy (SFM) probe with a sample is studied theoretically as well as experimentally. To model the probe, a complex system composed of a macroscopic cantilever, a mesoscopic tip cone and a nanometric tip apex is proposed. The corresponding interaction is calculated analyt...
Modified DNA species have attracted the interest of the scientific community in the last years in a search for an appropriate molecular wire for the incoming nanotechnology. M-DNA, a complex of DNA with divalent metallic ions, is one of the candidates for a molecular wire. In this paper we describe the procedure to fabricate M-DNA using NiCl2 and C...
In this work we present two scanning force microscopy (SFM) techniques applied to the electrical characterization of V2O5 nanofibres with one end connected to a metallic electrode: first a non-contact imaging technique combined with the acquisition of current versus voltage curves in a selected spot, and second jumping mode SFM that allows simultan...
In this work theoretical considerations of the performance of scanning force microscopy jumping mode and tapping mode in liquids are discussed. A priori, jumping mode should improve in a liquid environment compared to in air while the situation for tapping mode should become worse. In order to confirm this we present jumping and tapping mode images...
A fundamental requirement for a molecule to be considered a molecular wire (MW) is the ability to transport electrical charge with a reasonably low resistance. We have carried out two experiments that measure first, the charge transfer from an electrode to the molecule, and second, the dielectric response of the MW. The latter experiment requires n...
We have developed a set of working modes for scanning probe microscopy (SPM), which generalizes the usual method of acquiring data. We call these modes three-dimensional (3D) modes. Using these modes it is possible to measure typical SPM magnitudes, such as, for example, the tunnel current, the normal force and the amplitude or frequency of the can...
Experimental measurements of the electrostatic properties of long molecules are presented in this work. It is shown that, in the case of carbon nanotubes, the electrostatic force between the scanning force microscopy tip and the sample enhances the network of nanotubes electrically connected to a metal electrode. On λ-DNA molecules the same kind of...
The capability of controllable and repeatable positioning in the subnanometer range is fundamental not only for scanning probe microscope applications, but also for nanotechnology in general. Up to now, piezoceramic actuators have been used for this purpose. However, these actuators are far from being ideal transducers. For precise metrological app...
In this letter, a method is presented to perform current versus voltage measurements on carbon nanotubes using the tip of a scanning force microscope as an electrode that can be positioned along the molecule. This method allows current versus voltage measurements to be carried out at any spot along a nanotube. By using this method, we present indic...
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In this work fundamental properties of the electrical transport of single-walled carbon nanotubes as a function of their length are investigated. For this purpose, we have developed a new technique that allows us to characterize electronic transport properties of single-walled carbon nanotubes by probing them at different spots. This technique uses...
Force measurements with atomic force microscopy (AFM) in liquid are subjected to the hydrodynamic drag force artifact (Fd) due to viscous friction of the cantilever with the liquid. This artifact may be especially relevant in microrheological studies of soft samples. Common approaches estimate Fd at a certain distance above the sample and subtract...
The structure of the Paired Helical filaments (PHF), a polymer of the microtubule associated protein tau, has been studied by Atomic Force Microscopy (AFM) and by cryoelectron microscopy. Mica and graphite were used as substrates in the AFM analysis with no differences in the results. A banding pattern of 8–12 nm width within the helical structure...
The electrostatic interaction between a model probe and a sample in a scanning probe microscope is analyzed. A simple model for a real experimental setup is proposed and solved by means of an appropriate approximation. In addition, a quantitative definition for resolution is presented. We find that generally the total force between tip and sample i...
In this letter, a method is presented to qualitatively investigate the electrical connection between single-walled carbon nanotubes and gold electrodes. By applying a time independent bias voltage to the scanning force microscope tip, there is a clear apparent growth effect in the topography of the electrically connected carbon nanotubes. This effe...
In this work, a study of the possibilities of the Scanning Force Microscope (SFM) for studying transport properties of carbon nanotubes (CNTs) was done. Single-walled carbon nanotubes were deposited on SiO<sub>2</sub>. Afterwards, using a mask, the surface was covered with gold, so that some of the carbon nanotubes in the surface stick out undernea...
