Archaeometric analysis of ceramic production in Tiwanaku state (c.500-1000ce) : An exploratory study

The chemical and mineralogical characterization of seven ceramic fragments produced within Tiwanaku state (c.500-1000 ce) is reported. The instrumental techniques used included X-ray elemental and mineralogical chemical analysis, Raman spectroscopy, and scanning and light microscopy. The results indicate there are several clay types, although they show similarities, such as the use of a plant-based temper. The red colour of the decoration is hematite, and manganese oxides such as jacobsite are present in the black. The white colour is a mixture of gypsum and clay, and the orange is a mixture of hematite and clay. The use of colours, the quality of the clays and the temperatures reached during pottery firing point to expertise in ceramic production and to complex decision-making processes. The multi-elemental archaeometric approach documented here could become an important tool to shed a light on ancient ceramic technology and the internal variance of Tiwanaku pottery.Peer reviewe

Detection of PAHs on calixarene-functionalized metal surfaces by means of SERS spectroscopy

[ES]Se han detectado trazas de hidrocarburos aromaticos policiclicos (PAHs) por espectroscopia SERS. Para conseguir este fin, se han desarrollado nuevos sustratos SERS formados por nanoparticulas de plata, tanto en suspension como inmovilizadas sobre vidrio. Estas nanoparticulas se cubrieron de moleculas de calix[4]arenos autoensambladas. Entre las moleculas de calixarenos ensayadas, el 25,27-dicarboethoxy-26,28-dihydroxy-p-tert-butylcalix[4]areno presenta una mayor selectividad analitica hacia los PAHs formados por cuatro anillos bencenicos, principalmente el pireno. El mecanismo de la interaccion entre el calixareno y el PAH parece tener lugar a traves de un empaquetamiento ƒÎ . ƒÎ que conduce a una transferencia de carga entre el complejo y la superficie metalica. Esta interccion puede inducir tambien cambios en la carga superficial de las nanoparticulas metalicas[EN]Polycyclic Aromatic Hydrocarbons (PAHs) were detected at trace concentrations. In order to accomplish that, new SERS substrates were developed based on silver nanoparticles, both in suspension and immobilized in glass. These nanoparticles were covered by self-assembled calix[4]arene molecules. Among the assayed calixarene molecules, the 25,27-dicarboethoxy- 26,28-dihydroxy-p-tert-butylcalix[4]arene shows a higher analytical selectivity towards PAHs integrated by four benzene rings, mainly pyrene. The interaction mechanism between the calixarene and PAHs seems to take place through a ð–ð stacking leading to a charge-transfer between the complex and the metal surface. This interaction seems to also induce changes in the surface charge of the metallic particlesEste trabajo ha sido financiado parcialmente por el MEC (Proy.: FIS2004-00108), la Comunidad de Madrid (Proy.: MICROSERES; S-0505/TIC/0191) y el Acuerdo Bilateral CSIC-CONICYT (Proy.: 2005CL0002). Los autores expresan su agradecimiento a estos Organismos.pPeer reviewe

Vibrational interpretation of the structure of Co(II), VO2+ and Pb(II) naphthalocyanine complexes

The FT-IR and Raman spectra for the solid naphthalocyanine (H2Nc) and their Co(II), VO2+ and Pb(II) complexes were registered, and a band assignment was proposed. On this basis, the structure of the complexes was inferred: The Co(II) and VO2+ complexes are deformed macrocycles, and the Pb ion is out of the plane of the Nc fragment

Raman spectroscopy and x-ray fluorescence in molecular analysis of yellow blocks from the archeological site playa miller 7 (northern Chile)

Yellow blocks from the archaeological site Playa Miller 7 (PLM7), on the coast of Atacama Desert in northern Chile, were analyzed by Raman spectroscopy and X-ray fluorescence (XRF) portable. Our results identify for the first time the use of K-jarosite and natrojarosite in prehispanic times (approx. 2500 year BP). In search of a possible source of supply for this mineral hydrothermal origin, our surveys were focused on Andean geothermal areas with identification, so far, from a single source in the region of Arica and Parinacota: Jurasi (JU), located at 4000 mamsl. Comparison of the Raman spectra between samples archaeological and Jurasi, allow us to infer that this hydrothermal source could be used as obtaining source of yellow pigment by prehispanic inhabitant of Formative period (3700-1500 years B.P.)

Infrared and theoretical interpretation of the structure of naphthalocyanine and its copper(II) complex deposited onto a smooth copper surface

The infrared spectra of naphthalocyanine (H2Nc) and its copper(II) complex (CuNc) were registered in the region 4000-450 cm-1. These compounds were deposited onto a smooth copper surface and their specular infrared spectra were compared with those of the compounds dispersed in KBr and deposited onto a KBr monocrystal. The differences observed in the spectra of the macrocycle complex were interpreted in terms of slights structural modifications of the macrocycle complex caused by the interaction with the copper surface. The most probable orientation and the energy of the interaction were evaluated through out a simplified molecular model and using INDO/1 and Extended Hückel semiempirical methods. © 1998 Elsevier Science B.V. All rights reserved

Specular reflectance infrared spectra of the macrocycles cyclam and cyclamdione and their Cu( II) complexes deposited onto a smooth copper surface

An infrared study of the macrocycles cyclam, cyclamdione and its Cu(II) complexes has been performed. The specular reflectance infrared spectrum was recorded and analyzed for the ligands and complexes deposited onto a smooth copper surface. Several spectral modifications resulting from the macrocycle-metal surface interaction are interpreted in terms of molecular structural changes. An orientation of the ligands and complexes onto the metal surface is proposed. © 1997 Elsevier Science B.V

Analysis of biomolecules in cochineal dyed archaeological textiles by surface-enhanced Raman spectroscopy

11 pags., 5 figs.SERS spectroscopy is successfully employed in this work to reveal different components integrating the cochineal colorant employed for dying archaeological textile samples from the Arica Region in North Chile. This analysis was done by in-situ experiments that does not imply the material (colorant and biomolecules) extraction. The spectroscopic analysis of the archaeological textiles by SERS reveals the presence of bands attributed to carminic acid and nucleobases, mainly adenine and guanine. The identification of these biomolecules was also verified in raw cochineal extract and in cochineal dyed replica wool fibers fabricated by us following ancient receipts. The effect of Al on the complexation of carminic acid and other biomolecules was also tested in order to understand the changes induced by the metal interaction on the colorant structure. This study revealed that Al can also complex biomolecules existing in the cochineal extract. In particular, guanine residue seems to interact strongly with the metal, since SERS bands of this residue are enhanced. Furthermore, a theoretical analysis on the interaction of carminic acid and a silver surface was also performed in order to better understand the interaction mechanism between carminic acid and a metal surface that leads to the final SERS spectrum. The results of the present work will be very useful in the identification of different molecules and metal complexes that may be forming part of the cochineal colorant found in archaeological materials.S.S.C., M.C.V. and F.C. acknowledge the i-COOP+2015 Program of CSIC, project COOPB20146. C.S. acknowledges to Conicyt 21150397. F.C. acknowledges Fondecyt project 3150222 and CNE 10-1920 project funded by the Universidad de Playa Ancha (Concurso Regular de Investigación 2018). S.S.C. and F.C. also thanks the MINECO/ FEDER project FIS2017-84318-R

Surface vibrational study of macrocycle complexes: Co(II), Ni(II), Cu(II) and Zn(II) bis(phenylhydrazine)-1,10-phenanthroline

A complete assignment of the infrared spectra of the title macrocycles was carried out on the basis of well-documented references and a normal coordinate analysis based on a simplified molecular model. The structure of the complexes has been inferred from IR and UV-VIS data. Infrared reflection-absorption (IRRAS) spectra using a smooth copper surface and surface enhanced Raman spectra of samples dissolved in colloidal silver were registered. The non-planar structure of the coordination site and the sterical hindrance imposed by phenyl substituent fragments avoid any adsorbate-substrate interaction

Fluorescence and surface-enhanced vibrational spectroscopies of lawsone and plumbagin

<p>The natural dyes lawsone and plumbagin (1,4-naphthoquinones) were studied by using fluorescence, Raman, infrared (IR), surface-enhanced Raman scattering (SERS), and surface-enhanced IR absorption. From the absorption spectrum, it was possible to infer that the enol-lawsone tautomer concentration decreases in silver colloidal solution. Plumbagin dimers, both in water and in silver colloidal solution, were identified from the fluorescence band profile and surface-SERS spectrum. The SERS spectrum of lawsone was obtained by using silver colloidal solution after 12-hour settle; the keto and enol lawsone silver colloid interaction occurs. The assignment of Raman and IR bands of both dyes was calculated with density functional theory calculations. Only a monomeric structure of lawsone interacting with a silver cluster model was predicted. The monomer adopts a nearly coplanar orientation onto the silver surface; the shortest distance is 3.2 Å, suggesting an electrostatic interaction.</p