Search results for "ftir"
showing 10 items of 146 documents
Contribution and limitation of infrared spectroscopy technique to understand physisorption processes on MFI zeolites
2011
This manuscript is devoted to the study of adsorption processes by FTIR spectroscopy. The experimental results concern the adsorption of ethylene, trichloroethylene, tetrachloroethylene, sulfur hexafluoride or p-xylene on MFI zeolites, more especially on silicalite-1. The first step of the work was to develop a new experimental device and procedure in order to obtain reliable absorption infrared data and to improve results previously obtained by a prototype. The first main result is to characterize, maybe for the first time, the evolution of the spectrum of the adsorbent all during the adsorption process. Experiments reveal that the zeolite infrared spectrum undergoes strong modifications w…
Aportación de nuevas metodologías multitécnica en el estudio y conservación de patrimonio numismático de procedencia subacuática
2019
Este trabajo presenta un estudio del estado de conservación de monedas con base de cobre procedente del Museo Nacional de Arqueología Subacuática. La metodología multitécnica incluye instrumentación convencional como microscopía óptica, espectroscopia FTIR y técnicas avanzadas nanoinvasivas como voltamperometría de micropartículas y haz de iones focalizados-FESEM-EDX. Así se ha podido identificar el tipo de aleación, productos de corrosión, depósitos superficiales y antiguas intervenciones. Cabe señalar la identificación de mecanismos de alteración atípicos como la formación de complejos carboxilados de iones metálicos generados en los procesos electroquímicos de corrosión del metal o aleac…
Mikroplastmasas sastāva un telpiskās izplatības raksturojums Latvijas jurisdikcijā esošo jūras ūdeņu virskārtā - Austrumgotlandes baseinā un Rīgas lī…
2021
Latvijas jūras ūdeņos tika ievākti 46 ūdens virskārtas plastmasas paraugi, izmantojot Manta tīklu. Organiskā materiāla sadalīšanai secīgi tika izmantots nātrija hidroksīds, ūdeņraža peroksīds un enzīmi. Plastmasas daļiņas tika identificētas un raksturotas vizuāli, un noteikts to veidojošais polimērs. Plastmasas daļiņas bija sastopamas visās paraugu ņemšanas vietās koncentrācijā no 0,09 līdz 4,43 daļiņām/m3. Izplatītākais daļiņu veids bija šķiedras (54,92%) un plastmasas fragmenti (40,18%). Dominējošie polimēri bija polietilēns (80,18%) un polipropilēns (11,81%), tomēr relatīvā proporcija starp polimēru veidiem katrā stacijā ievērojami atšķīrās. Precīzākai plastmasas piesārņojuma novērtēšana…
Mikroplastmasas izplatība Baltijas jūras Austrumgotlandes un Rīgas līča Latvijas jurisdikcijas ūdeņu sedimentu virsējā slānī
2021
Bakalaura darba veikšanai tika ievākti 13 mikroplastmasas paraugi no Baltijas jūras Austrumgotlandes un Rīgas līča Latvijas jurisdikcijas ūdeņu sedimentu virsējā slāņa. Tie secīgi tika apstrādāti izmantojot blīvumseparāciju un organiskā materiāla ķīmiskās sadalīšanas metodi. Tika veikta paraugu vizuālā analīze un noteikts plastmasas daļiņu veidojošais polimērs, izmantojot Mikro Furjē transformācijas infrasarkanās gaismas spektroskopijas metodi. Tika izstrādāta un attīstīta sedimentu mikroplastmasas paraugu apstrādes metode, nosakot piemērotāko apakšējā izmēra robežu, šķirpiltuves tilpumu, blīvumseparācijas atkārtošanas skaitu, kā arī enzimātisko reakciju piemērošanu paraugu apstrādei. Mikro…
A FTIR study on low hydration saccharide amorphous matrices: Thermal behaviour of the Water Association Band
2011
Abstract We report a study on the thermal behaviour of the infrared Water Association Band (WAB) in dry binary saccharide–water systems (containing trehalose, sucrose, maltose, and raffinose). This is a follow-up of preceding studies on analogous carboxymyoglobin-saccharide–water ternary systems, which pointed out a mutual protein-matrix influence (coupling). A comparison between binary and ternary systems, for all the saccharides studied, evidences a reduction in the residual water content in the latter and, except for trehalose, a sizable modification in the thermal behaviour, which is discussed in terms of structure and hydrogen bonding properties of the sugars. The study allowed us also…
The majolica production of Northern central Sicily (16th - 18th Century AD): Archaeometric evidence
2007
Investigation of phthalocyanine crystals exposed to NO2 ambient gas
2002
Crystals of free base phthalocyanine (H2pc) and its unsubstituted metal derivatives Mpc (where M=Ni, Cu, Zn, Pb, and pc=C32H16N8 2−=phthalocyanine ligand) were examined after being exposed to NO2 ambient gas. Scanning electron microscopy (SEM) supported by X-ray microprobe analysis (EDAX), UV–Vis and FTIR spectroscopy as well as X-ray powder diffractometry (XRD) were applied to study the crystals chemistry and surface morphology. The NO2 molecules were found to penetrate the crystal unit which led to the breakdown of the phthalocyanine macrocycle. The surface of the doped crystals has been scaled and covered by a layer composed predominantly of phthalimide. Despite vacuum desorption, it has…
Characterization of prehispanic cosmetics found in a burial of the ancient city of Teotihuacan (Mexico)
2012
The present paper reports the chemical data obtained on samples of pigmenting materials contained in 31 miniature vessels found in a burial found in Teopancazco, a multiethnic neighborhood center located in the southeastern sector of the archaeological site of Teotihuacan (Central Mexico) and the analytical protocol established for the complete characterization of these archaeological materials. For this purpose a multi-technique approach based on the combination of several non destructive and micro-destructive instrumental techniques, namely, light microscopy (LM), scanning electron microscopy-X-ray micro-analysis (SEMe EDX), transmission electron microscopy (TEM), voltammetry of micropart…
High resolution study of the six lowest doubly excited vibrational states of PH2D
2005
Abstract The five lowest doubly excited deformational vibrational bands ν 4 + ν 6 , 2 ν 6 , ν 3 + ν 4 , ν 3 + ν 6 , and 2 ν 3 of PH 2 D have been recorded for the first time using a Bruker 120 HR interferometer with a resolution 0.0033 cm −1 and analysed. Some transitions belonging to a very weak band 2 ν 4 have been also assigned. From the fit 24 and 86, respectively, diagonal and resonance interaction parameters were obtained which reproduce 1089 upper energy levels obtained from more than 4600 assigned transitions with the rms deviation of 0.00059 cm −1 .
Infrared Spectroscopy of Ruthenium Tetroxide and High-resolution analysis of the v3 band
2015
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