Jose V Garcia-Ramos - Academia.edu (original) (raw)
Papers by Jose V Garcia-Ramos
![Research paper thumbnail of Functionalization of Ag nanoparticles with dithiocarbamate calix [4] arene as an effective supramolecular host for the surface-enhanced Raman scattering detection of …](https://attachments.academia-assets.com/72835680/thumbnails/1.jpg)
](Langmuir, 2006
We report the use of 25,27-diethyl-dithiocarbamic-26,28-dihydroxy-p-tert-butylcalix[4]arene in th... more We report the use of 25,27-diethyl-dithiocarbamic-26,28-dihydroxy-p-tert-butylcalix[4]arene in the functionalization of Ag nanoparticles for pyrene detection by surface-enhanced Raman scattering (SERS). SERS spectra provided information about the calixarene orientation on the metal ...
Langmuir : the ACS journal of surfaces and colloids, Jan 9, 2018
In this work we report a broad scenario for the patterning of semiconducting polymers by laser-in... more In this work we report a broad scenario for the patterning of semiconducting polymers by laser-induced periodic surface structures (LIPSS). Based on the LIPSS formation in the semicrystalline poly(3-hexylthiophene) (P3HT), we have extended the LIPSS fabrication to an essentially amorphous semiconducting polymer like poly[N-90-heptadecanyl-2,7-carbazole-alt-5,5-(40,70-di-2-thienyl-20,10,30-benzothiadiazole)] (PCDTBT). This polymer shows a good quality and well-ordered nanostructures not only at the 532 nm laser wavelength, as in the case of P3HT, but also at 266 nm providing gratings with smaller pitch. In addition, we have proven the feasibility of fabricating LIPSS in the P3HT/PCDTBT (1:1) blend, which can be considered as a model bulk-heterojunction for all-polymer solar cells. In spite of the heterogeneous roughness, due to phase separation in the blend, both P3HT and PCDTBT domains present well-defined LIPSS as well as a synergy for both components in the blend when irradiating ...
Journal of the Chemical Society, Faraday Transactions 2
One of the two fundamental mechanisms underlying Surface-Enhanced Raman Scattering (SERS) is the ... more One of the two fundamental mechanisms underlying Surface-Enhanced Raman Scattering (SERS) is the existence of large electromagnetic (EM) fields in the vicinity of the rough metal substrates that are used as substrates. Surface roughness below the micron scale plays a relevant role in this process, due to the roughness-induced excitation of surface-plasmon polaritons. Since in many scattering configurations dipolar and/or
3rd Iberoamerican Optics Meeting and 6th Latin American Meeting on Optics, Lasers, and Their Applications, 1999
ABSTRACT
![Research paper thumbnail of Reflection–absorption IR and surface-enhanced IR spectroscopy of tetracarboethoxy t-butyl-calix[4]arene, as a host molecule with potential applications in sensor devices](https://attachments.academia-assets.com/71095700/thumbnails/1.jpg)
](Vibrational Spectroscopy, 2007
A vibrational study of the calix[4]arene derivative 25,26,27,28-tetracarboethoxy-p-tert-butylcali... more A vibrational study of the calix[4]arene derivative 25,26,27,28-tetracarboethoxy-p-tert-butylcalix[4]arene (TCEC) is accomplished in this work. This characterization implies a study of its adsorption on metal (Cu and Ag) films by reflection-absorption IR spectroscopy (RAIRS) and surface-enhanced IR (SEIR) in transmission and reflection-absorption configurations. Metal surfaces for SEIR were obtained by a simple direct immobilization on Ge of Ag nanoparticles suspended in water. The goal of this research was an accurate vibrational characterization of the above calixarene molecule, paying special attention in the structural marker bands of ester groups, which play an important role in the molecular adsorption on such metals. The information derived from this study will serve to better understand the interaction of ester-functionalised calixarenes with these metals, in order to prepare sensor films with selective affinity towards polycyclic aromatic hydrocarbons (PAHs). The application of these surface techniques confirmed the importance of the ester groups in the immobilization and self-assembly of these host molecules to the metal surface and provided information about the orientation adopted by TCEC on the metal.
Lecture Notes in Physics, 2000
... with its far field expression, which yields the angular distribution of scattered light (θs b... more ... with its far field expression, which yields the angular distribution of scattered light (θs being the ... part of the plot) is scattered due to the surface roughness: The interference between the ... and scattered fields gives rise to the observed intensity pattern with horizontal fringes of length ...
Laser Applications in Life Sciences, 1991
ABSTRACT
In recent years the combination of Raman scattering and microscopy has opened a new frontier in t... more In recent years the combination of Raman scattering and microscopy has opened a new frontier in the biological application of Raman spectroscopy. Micro-Raman has taken advantage from the impressive technical improving of laser and detection devices which nowadays allows the study of materials with reduced dimensions and small objects such as cells or tissues. In addition Raman imaging provides a
The optical properties of metallic Nanoparticles have a big scientific and technological importan... more The optical properties of metallic Nanoparticles have a big scientific and technological importance. Such properties are determined by the Localized Surface Plasmons (LSP) the nanoparticles (NPs) support, which strongly depend on the NPs size and shape. The resonant excitation of the LSP leads to enormous enhancement of the electromagnetic field in close proximity of the NPs which originates a very
Physica Status Solidi B-basic Solid State Physics, 2000
ABSTRACT The determination of particle size distribution on aerosols and suspensions was carried ... more ABSTRACT The determination of particle size distribution on aerosols and suspensions was carried out by ultraviolet-visible-near infrared absorbance measurements following a new procedure for the case of absorbing (complex refractive index) particles. This procedure consists in an analysis of subranges of radii where the discretization curve is continuous, taking as final particle size distribution the inverse solution corresponding to the subrange for which the direct problem gives better results (minimun rme value). Following the procedure, silver colloidal particles in water suspensions were analyzed obtaining a retrieved particle size distribution with characteristics that agree very well with the manufacturing data.
Nanostructure Science and Technology, 2007
... JOSE A. SANCHEz-GIL,t JOSE V. GARCiA-RAMOS,t VINCENZO GIANNINI,t AND EUGENIO R. MENDEZ+ tlnst... more ... JOSE A. SANCHEz-GIL,t JOSE V. GARCiA-RAMOS,t VINCENZO GIANNINI,t AND EUGENIO R. MENDEZ+ tlnstituto de Estructura de La ... 34The ensembles of realizations thus generated are charac-terized by their fractal dimension D == 2 - H (H being the Hurst exponent) and ...
AIP Conference Proceedings, 2010
Langmuir, 2010
The adsorption of beta(2)-adrenergic agonist (βAA) drugs clenbuterol, salbutamol, and terbutaline... more The adsorption of beta(2)-adrenergic agonist (βAA) drugs clenbuterol, salbutamol, and terbutaline on metal surfaces has been investigated in this work by means of surface-enhanced Raman scattering (SERS). To assist in this investigation, a previous vibrational (IR and normal Raman) characterization of these drugs was performed, supported by ab initio density functional theory calculations. The application of SERS was aimed to apply this highly sensitive technique, based on localized surface plasmon resonance, in the detection of βAA at trace concentrations and as a possible alternative method which can be postulated in routine antidoping analysis. The adsorption of these drugs was studied in depth at different experimental conditions: on Au and Ag, at different pHs, and with varying adsorbate concentration. Moreover, plasmon resonance spectroscopy was employed to investigate the adsorption of these drugs on the metal nanoparticles as well as their aggregation. It was found that the adsorption of these molecules is more effective on gold nanoparticles and at acidic pH, based on the direct interaction of the aromatic or aliphatic moieties through ionic or coordination bonds with the metal. These drugs followed a Langmuir adsorption model from which the adsorption constant and the limit of detection can be determined.
The Journal of Physical Chemistry, 1996
... Fernández-Liencres, Amparo Navarro, Juan J. López, and Manuel Fernández. ... Viktor Szalay. R... more ... Fernández-Liencres, Amparo Navarro, Juan J. López, and Manuel Fernández. ... Viktor Szalay. Research Laboratory for Crystal Physics, Hungarian Academy of Sciences, PO Box 132, 1502 Budapest, Hungary. Teresa de los Arcos, José V. García-Ramos, and Rafael M. Escribano* ...
Vibrational Spectroscopy, 2008
A humic acid (HA) extracted from lignite was successfully used in surface-enhanced Raman scatteri... more A humic acid (HA) extracted from lignite was successfully used in surface-enhanced Raman scattering SERS experiments as molecular occlusion assembler deposited onto a Ag colloidal surface to detect the polycyclic aromatic hydrocarbons PAHs chrysene and pyrene. Thus, this is the first time that HA compounds are employed in the design of metal nanoparticles-based sensors for pollutants detection. Chrysene (Chr) and pyrene (Pyr) were detected at low concentration. A charge transfer between HA and the analyte characterizes their interaction. The interaction resulted to be more significant in the case of the pyrene molecule. Extended Hückel calculations based on a molecular model for the interacting PAHs/HA/Ag system support the experimental conclusions. The PAHs-HA distance is about 3.5 Å and the most probable orientation for both analytes is plane parallel to the aromatic fragments of HA. An energy transfer, from the silver surface to HA and from the analyte to HA, is concluded.
Vibrational Spectroscopy, 2008
A surface-enhanced Raman scattering (SERS) study of diquat (DQ) is reported in this work for the ... more A surface-enhanced Raman scattering (SERS) study of diquat (DQ) is reported in this work for the first time. Previously, we have accomplished the assignment of the Raman spectra of DQ and its radical cation DQ on the basis of theoretical DFT calculations. SERS spectra on Ag colloid were obtained at different conditions: varying the added anion, the surface coverage and the excitation wavelength. Structural marker bands related to the molecular planarity and the environment of N atoms were identified on the basis of the calculated frequencies and the SERS spectra. The analysis of SERS spectra at different conditions revealed that two DQ species are present on the metal surface: DQ attached to the surface through the formation of charge-transfer (CT) complexes with adsorbed anion, bearing a structure similar to that of DQ , and other DQ species which are adsorbed on the metal forming multilayers.
The Journal of Physical Chemistry C, 2008
The application of viologen dications in the creation of highly sensitive and selective hot spots... more The application of viologen dications in the creation of highly sensitive and selective hot spots between silver nanoparticles is reported in the present work. A method to follow the existence of such hot spots in macroscopic samples is proposed based on the plasmon absorption ...
![Research paper thumbnail of Selective Molecular Recognition of Polycyclic Aromatic Hydrocarbons (PAHs) on Calix[4]arene-Functionalized Ag Nanoparticles by Surface-Enhanced Raman Scattering](https://attachments.academia-assets.com/71095692/thumbnails/1.jpg)
](The Journal of Physical Chemistry B, 2004
Trace concentrations of polycyclic aromatic hydrocarbons (PAHs) have been successfully detected u... more Trace concentrations of polycyclic aromatic hydrocarbons (PAHs) have been successfully detected using surface-enhanced Raman scattering (SERS) spectroscopy. For such purpose, new SERS substrates have been developed, consisting of Ag nanoparticles, either in suspension or immobilized on glass, obtained by a new method and covered by adsorbed self-assembled calix[4]arene molecules. Among the assayed calix[4]arenes, the 25,27-dicarboethoxy-26,28-dihydroxy-p-tert-butylcalix[4]arene host molecule displays analytical selectivity to the PAH guest systems bearing four benzene rings, mainly pyrene. The host-guest interaction mechanism seems to take place through a π-π stacking interaction leading to a charge transfer between the complex and the metallic surface, which may also induce a notable influence on the surface charge of the metallic nanoparticle.
The Journal of Physical Chemistry A, 2003
... EA Carrasco F., M. Campos-Vallette, † P. Leyton, † G. DiazF., ‡ RE Clavijo, † JV García-Ramos... more ... EA Carrasco F., M. Campos-Vallette, † P. Leyton, † G. DiazF., ‡ RE Clavijo, † JV García-Ramos, § N. Inostroza, † C. Domingo, § S. Sanchez-Cortes,* § and R. Koch #. University of Chile, Faculty of Sciences, PO Box 653, Santiago ...
Langmuir, 2006
We report the use of 25,27-diethyl-dithiocarbamic-26,28-dihydroxy-p-tert-butylcalix[4]arene in th... more We report the use of 25,27-diethyl-dithiocarbamic-26,28-dihydroxy-p-tert-butylcalix[4]arene in the functionalization of Ag nanoparticles for pyrene detection by surface-enhanced Raman scattering (SERS). SERS spectra provided information about the calixarene orientation on the metal ...
Langmuir : the ACS journal of surfaces and colloids, Jan 9, 2018
In this work we report a broad scenario for the patterning of semiconducting polymers by laser-in... more In this work we report a broad scenario for the patterning of semiconducting polymers by laser-induced periodic surface structures (LIPSS). Based on the LIPSS formation in the semicrystalline poly(3-hexylthiophene) (P3HT), we have extended the LIPSS fabrication to an essentially amorphous semiconducting polymer like poly[N-90-heptadecanyl-2,7-carbazole-alt-5,5-(40,70-di-2-thienyl-20,10,30-benzothiadiazole)] (PCDTBT). This polymer shows a good quality and well-ordered nanostructures not only at the 532 nm laser wavelength, as in the case of P3HT, but also at 266 nm providing gratings with smaller pitch. In addition, we have proven the feasibility of fabricating LIPSS in the P3HT/PCDTBT (1:1) blend, which can be considered as a model bulk-heterojunction for all-polymer solar cells. In spite of the heterogeneous roughness, due to phase separation in the blend, both P3HT and PCDTBT domains present well-defined LIPSS as well as a synergy for both components in the blend when irradiating ...
Journal of the Chemical Society, Faraday Transactions 2
One of the two fundamental mechanisms underlying Surface-Enhanced Raman Scattering (SERS) is the ... more One of the two fundamental mechanisms underlying Surface-Enhanced Raman Scattering (SERS) is the existence of large electromagnetic (EM) fields in the vicinity of the rough metal substrates that are used as substrates. Surface roughness below the micron scale plays a relevant role in this process, due to the roughness-induced excitation of surface-plasmon polaritons. Since in many scattering configurations dipolar and/or
3rd Iberoamerican Optics Meeting and 6th Latin American Meeting on Optics, Lasers, and Their Applications, 1999
ABSTRACT
Vibrational Spectroscopy, 2007
A vibrational study of the calix[4]arene derivative 25,26,27,28-tetracarboethoxy-p-tert-butylcali... more A vibrational study of the calix[4]arene derivative 25,26,27,28-tetracarboethoxy-p-tert-butylcalix[4]arene (TCEC) is accomplished in this work. This characterization implies a study of its adsorption on metal (Cu and Ag) films by reflection-absorption IR spectroscopy (RAIRS) and surface-enhanced IR (SEIR) in transmission and reflection-absorption configurations. Metal surfaces for SEIR were obtained by a simple direct immobilization on Ge of Ag nanoparticles suspended in water. The goal of this research was an accurate vibrational characterization of the above calixarene molecule, paying special attention in the structural marker bands of ester groups, which play an important role in the molecular adsorption on such metals. The information derived from this study will serve to better understand the interaction of ester-functionalised calixarenes with these metals, in order to prepare sensor films with selective affinity towards polycyclic aromatic hydrocarbons (PAHs). The application of these surface techniques confirmed the importance of the ester groups in the immobilization and self-assembly of these host molecules to the metal surface and provided information about the orientation adopted by TCEC on the metal.
Lecture Notes in Physics, 2000
... with its far field expression, which yields the angular distribution of scattered light (θs b... more ... with its far field expression, which yields the angular distribution of scattered light (θs being the ... part of the plot) is scattered due to the surface roughness: The interference between the ... and scattered fields gives rise to the observed intensity pattern with horizontal fringes of length ...
Laser Applications in Life Sciences, 1991
ABSTRACT
In recent years the combination of Raman scattering and microscopy has opened a new frontier in t... more In recent years the combination of Raman scattering and microscopy has opened a new frontier in the biological application of Raman spectroscopy. Micro-Raman has taken advantage from the impressive technical improving of laser and detection devices which nowadays allows the study of materials with reduced dimensions and small objects such as cells or tissues. In addition Raman imaging provides a
The optical properties of metallic Nanoparticles have a big scientific and technological importan... more The optical properties of metallic Nanoparticles have a big scientific and technological importance. Such properties are determined by the Localized Surface Plasmons (LSP) the nanoparticles (NPs) support, which strongly depend on the NPs size and shape. The resonant excitation of the LSP leads to enormous enhancement of the electromagnetic field in close proximity of the NPs which originates a very
Physica Status Solidi B-basic Solid State Physics, 2000
ABSTRACT The determination of particle size distribution on aerosols and suspensions was carried ... more ABSTRACT The determination of particle size distribution on aerosols and suspensions was carried out by ultraviolet-visible-near infrared absorbance measurements following a new procedure for the case of absorbing (complex refractive index) particles. This procedure consists in an analysis of subranges of radii where the discretization curve is continuous, taking as final particle size distribution the inverse solution corresponding to the subrange for which the direct problem gives better results (minimun rme value). Following the procedure, silver colloidal particles in water suspensions were analyzed obtaining a retrieved particle size distribution with characteristics that agree very well with the manufacturing data.
Nanostructure Science and Technology, 2007
... JOSE A. SANCHEz-GIL,t JOSE V. GARCiA-RAMOS,t VINCENZO GIANNINI,t AND EUGENIO R. MENDEZ+ tlnst... more ... JOSE A. SANCHEz-GIL,t JOSE V. GARCiA-RAMOS,t VINCENZO GIANNINI,t AND EUGENIO R. MENDEZ+ tlnstituto de Estructura de La ... 34The ensembles of realizations thus generated are charac-terized by their fractal dimension D == 2 - H (H being the Hurst exponent) and ...
AIP Conference Proceedings, 2010
Langmuir, 2010
The adsorption of beta(2)-adrenergic agonist (βAA) drugs clenbuterol, salbutamol, and terbutaline... more The adsorption of beta(2)-adrenergic agonist (βAA) drugs clenbuterol, salbutamol, and terbutaline on metal surfaces has been investigated in this work by means of surface-enhanced Raman scattering (SERS). To assist in this investigation, a previous vibrational (IR and normal Raman) characterization of these drugs was performed, supported by ab initio density functional theory calculations. The application of SERS was aimed to apply this highly sensitive technique, based on localized surface plasmon resonance, in the detection of βAA at trace concentrations and as a possible alternative method which can be postulated in routine antidoping analysis. The adsorption of these drugs was studied in depth at different experimental conditions: on Au and Ag, at different pHs, and with varying adsorbate concentration. Moreover, plasmon resonance spectroscopy was employed to investigate the adsorption of these drugs on the metal nanoparticles as well as their aggregation. It was found that the adsorption of these molecules is more effective on gold nanoparticles and at acidic pH, based on the direct interaction of the aromatic or aliphatic moieties through ionic or coordination bonds with the metal. These drugs followed a Langmuir adsorption model from which the adsorption constant and the limit of detection can be determined.
The Journal of Physical Chemistry, 1996
... Fernández-Liencres, Amparo Navarro, Juan J. López, and Manuel Fernández. ... Viktor Szalay. R... more ... Fernández-Liencres, Amparo Navarro, Juan J. López, and Manuel Fernández. ... Viktor Szalay. Research Laboratory for Crystal Physics, Hungarian Academy of Sciences, PO Box 132, 1502 Budapest, Hungary. Teresa de los Arcos, José V. García-Ramos, and Rafael M. Escribano* ...
Vibrational Spectroscopy, 2008
A humic acid (HA) extracted from lignite was successfully used in surface-enhanced Raman scatteri... more A humic acid (HA) extracted from lignite was successfully used in surface-enhanced Raman scattering SERS experiments as molecular occlusion assembler deposited onto a Ag colloidal surface to detect the polycyclic aromatic hydrocarbons PAHs chrysene and pyrene. Thus, this is the first time that HA compounds are employed in the design of metal nanoparticles-based sensors for pollutants detection. Chrysene (Chr) and pyrene (Pyr) were detected at low concentration. A charge transfer between HA and the analyte characterizes their interaction. The interaction resulted to be more significant in the case of the pyrene molecule. Extended Hückel calculations based on a molecular model for the interacting PAHs/HA/Ag system support the experimental conclusions. The PAHs-HA distance is about 3.5 Å and the most probable orientation for both analytes is plane parallel to the aromatic fragments of HA. An energy transfer, from the silver surface to HA and from the analyte to HA, is concluded.
Vibrational Spectroscopy, 2008
A surface-enhanced Raman scattering (SERS) study of diquat (DQ) is reported in this work for the ... more A surface-enhanced Raman scattering (SERS) study of diquat (DQ) is reported in this work for the first time. Previously, we have accomplished the assignment of the Raman spectra of DQ and its radical cation DQ on the basis of theoretical DFT calculations. SERS spectra on Ag colloid were obtained at different conditions: varying the added anion, the surface coverage and the excitation wavelength. Structural marker bands related to the molecular planarity and the environment of N atoms were identified on the basis of the calculated frequencies and the SERS spectra. The analysis of SERS spectra at different conditions revealed that two DQ species are present on the metal surface: DQ attached to the surface through the formation of charge-transfer (CT) complexes with adsorbed anion, bearing a structure similar to that of DQ , and other DQ species which are adsorbed on the metal forming multilayers.
The Journal of Physical Chemistry C, 2008
The application of viologen dications in the creation of highly sensitive and selective hot spots... more The application of viologen dications in the creation of highly sensitive and selective hot spots between silver nanoparticles is reported in the present work. A method to follow the existence of such hot spots in macroscopic samples is proposed based on the plasmon absorption ...
The Journal of Physical Chemistry B, 2004
Trace concentrations of polycyclic aromatic hydrocarbons (PAHs) have been successfully detected u... more Trace concentrations of polycyclic aromatic hydrocarbons (PAHs) have been successfully detected using surface-enhanced Raman scattering (SERS) spectroscopy. For such purpose, new SERS substrates have been developed, consisting of Ag nanoparticles, either in suspension or immobilized on glass, obtained by a new method and covered by adsorbed self-assembled calix[4]arene molecules. Among the assayed calix[4]arenes, the 25,27-dicarboethoxy-26,28-dihydroxy-p-tert-butylcalix[4]arene host molecule displays analytical selectivity to the PAH guest systems bearing four benzene rings, mainly pyrene. The host-guest interaction mechanism seems to take place through a π-π stacking interaction leading to a charge transfer between the complex and the metallic surface, which may also induce a notable influence on the surface charge of the metallic nanoparticle.
The Journal of Physical Chemistry A, 2003
... EA Carrasco F., M. Campos-Vallette, † P. Leyton, † G. DiazF., ‡ RE Clavijo, † JV García-Ramos... more ... EA Carrasco F., M. Campos-Vallette, † P. Leyton, † G. DiazF., ‡ RE Clavijo, † JV García-Ramos, § N. Inostroza, † C. Domingo, § S. Sanchez-Cortes,* § and R. Koch #. University of Chile, Faculty of Sciences, PO Box 653, Santiago ...