A miniature UV-VIS spectrometer for the surface of Mars

A miniature spectrometer is in the process of development for a future Mars mission, to measure the UV-VIS spectrum encountered at the martian surface. With an intended mass of ~100 g, the spectrometer is planned as part of the ESA ExoMars mission

Uv-Vis Spectrum Analysis Of Heavy Metal Detection

UV-Vis spectroscopy is routinely used in the quantitative determination of solutions of transition metal ions and highly conjugated compounds. One of its applications is to find the molar absorptivity of different kind of heavy metals ions. Using molar absorptivity, concentration of heavy metals ions can be deduced based on the established calibration curve. This calibration curve first need to be constructed by repeatedly analyzed it UV-Vis spectrum analysis of the concerned ion with controlled concentration. The plot between known concentration and its corresponding absorptivity is used as a calibration curve to predict the unknown concentration of samples based on it absorptivity. The aim of this project is to study several different type of relationship between the Uv-vis spectroscopy absorptivity and heavy metals ion concentration. Conventionally, the relationship between absorptivity intensity variable and it corresponding concentration are all assume as linear. Heavy metals on the other hand show non-linear correlation and when the calibration curve wrongly adapts same construction method, it gives high errors. From three tested model fitted, experiment show that quadratic model is the most suited model to explain the relationship. Apart from the relationship between variable, this project also investigates a multipoint predictor to improve the calibration accuracy. We apply multivariate analysis to the several data extracted from various location of uv-vis spectrum and transform it to single most accurate predictor variable. Partial Least Square Regression (PLSR) analysis proven superior both in prediction of sample concentration and the degree of line fitting to the point compared to Principle Component Regression (PCR) analysis method. PLSR is capable in providing lowest error when linear regression calibration curve are required. Apart from those two factors, the project also uncovers several key factors in helping to improve the accuracy, one of the factor consist of the properties of raw data extraction decision. Different location of point extraction location and different number of point required vary by the transformation method used, but in most occasion, highest peak and second highest peak in spectrum show better potential for both single point raw data and multiple point extracted for preprocessing. Preprocessing step is another factor that supports the improvement of the calibration curve. Instead using the intensity of absorptivity in a wavelength spectrum, different between chosen two points is used as a raw data. Overall, the best calibration curve is the combination of preprocessing step and quadratic model fit

Quantitatively Correct UV-vis Spectrum of Ferrocene with TDB3LYP

Cataloged from PDF version of article.The ultraviolet-visible light (UV-vis) absorption spectrum of ferrocene is modeled with time-dependent density functional theory employing LSDA, BLYP, B3LYP, and CAM-B3LYP functionals in combination with 6-31G*, 6-31+G*, CC-PVTZ, and aug-CC-PVTZ basis sets. With the exception of LSDA, all functionals predict a reasonable Fe-CP distance of similar to 4.67 angstrom. Diffuse functions are essential for the strongly allowed states at high energy but of lesser consequence for the visible range of the spectrum. Dipole forbidden states are examined with vibrationally excited structures, obtained from the normal modes of the infrared (IR) spectrum. Despite earlier claims, TDB3LYP predicts the UV-vis spectrum of ferrocene quantitatively correct. TDBLYP predicts a large number of spurious charge-transfer states, TDCAM-B3LYP and TDwB97)CD are correct in the low-energy region but overestimate the energy of strongest peak of the spectrum by 0.8 eV. The amount of charge transfer involved in "d-d transitions" is equal to that in "charge-transfer states"

Low-cost, disposable colourimetric sensors for metal ions detection

Abstract In this work, two colourimetric sensors for metal ions detection are presented. The devices are obtained by fixing two classical dyes, Eriochrome Black T (EBT) and 1-(2-pyridylazo)-2-naphthol (PAN), on the commercial paper sheet "Colour Catcher®" (here named under the acronym CC) generally used in the washing machine to prevent colour run problems. The devices are optical sensors, since the indicator dye, fixed on the solid material, changes its spectral properties (colour and hence UV-vis spectrum) upon contact with the metal ion solution. We used the partial least squares (PLS) regression for obtaining the relationship between the metal ion content and the UV-vis spectrum change of each sensor

Dynamical Behavior of Probe Molecules and Dominant Role of Cosurfactants in Reverse Micelles

Reverse micelles (RM) are nanopools of water surrounded by surfactant molecules in a non-polar solvent. Our studies investigated properties of RM probe molecules in the interfacial boundary between water and non-polar solvents. Reichardt’s dye, a probe molecule, was used to uncover properties of RM. UV/vis spectroscopy of Reichardt’s dye reveals information about polarity and the dye’s approximate residential location and also helps confirm molecular orbital energy diagram. We discovered an interesting phenomenon with Reichardt’s dye in RM. Surprisingly, the UV/vis spectrum of Reicahrdt’s dye in CTAB RM with octanol as a cosurfactant exhibits decreasing absorbance and a blue shift. Reichardt’s dye in solely octanol shows an irreversible color change and similar UV/vis spectrum. Consequently, we conclude that Reichardt’s dye resides near the interfacial layer/solvent boundary. Other cosurfactants do not result in the time dependent behavior suggesting a more dynamic interaction between octanol and Reichardt’s dye

Dynamical Behavior of Probe Molecules and Dominant Role of Cosurfactants in Reverse Micelles

Reverse micelles (RM) are nanopools of water surrounded by surfactant molecules in a non-polar solvent. Our studies investigated properties of RM probe molecules in the interfacial boundary between water and non-polar solvents. Reichardt’s dye, a probe molecule, was used to uncover properties of RM. UV/vis spectroscopy of Reichardt’s dye reveals information about polarity and the dye’s approximate residential location and also helps confirm molecular orbital energy diagram. We discovered an interesting phenomenon with Reichardt’s dye in RM. Surprisingly, the UV/vis spectrum of Reicahrdt’s dye in CTAB RM with octanol as a cosurfactant exhibits decreasing absorbance and a blue shift. Reichardt’s dye in solely octanol shows an irreversible color change and similar UV/vis spectrum. Consequently, we conclude that Reichardt’s dye resides near the interfacial layer/solvent boundary. Other cosurfactants do not result in the time dependent behavior suggesting a more dynamic interaction between octanol and Reichardt’s dye

Uv-Vis Spectrum Analysis Of Heavy Metal Detection

UV-Vis spectroscopy is routinely used in the quantitative determination of solutions of transition metal ions and highly conjugated compounds. One of its applications is to find the molar absorptivity of different kind of heavy metals ions. Using molar absorptivity, concentration of heavy metals ions can be deduced based on the established calibration curve. This calibration curve first need to be constructed by repeatedly analyzed it UV-Vis spectrum analysis of the concerned ion with controlled concentration. The plot between known concentration and its corresponding absorptivity is used as a calibration curve to predict the unknown concentration of samples based on it absorptivity. The aim of this project is to study several different type of relationship between the Uv-vis spectroscopy absorptivity and heavy metals ion concentration. Conventionally, the relationship between absorptivity intensity variable and it corresponding concentration are all assume as linear. Heavy metals on the other hand show non-linear correlation and when the calibration curve wrongly adapts same construction method, it gives high errors. From three tested model fitted, experiment show that quadratic model is the most suited model to explain the relationship. Apart from the relationship between variable, this project also investigates a multipoint predictor to improve the calibration accuracy. We apply multivariate analysis to the several data extracted from various location of uv-vis spectrum and transform it to single most accurate predictor variable. Partial Least Square Regression (PLSR) analysis proven superior both in prediction of sample concentration and the degree of line fitting to the point compared to Principle Component Regression (PCR) analysis method. PLSR is capable in providing lowest error when linear regression calibration curve are required. Apart from those two factors, the project also uncovers several key factors in helping to improve the accuracy, one of the factor consist of the properties of raw data extraction decision. Different location of point extraction location and different number of point required vary by the transformation method used, but in most occasion, highest peak and second highest peak in spectrum show better potential for both single point raw data and multiple point extracted for preprocessing. Preprocessing step is another factor that supports the improvement of the calibration curve. Instead using the intensity of absorptivity in a wavelength spectrum, different between chosen two points is used as a raw data. Overall, the best calibration curve is the combination of preprocessing step and quadratic model fit

Longitudinal plasmonic detection of glucose using gold nanorods

Gold nanorod-based affinity sensors were developed utilizing concanavalin-A/dextran/glucose chemistry to detect glucose. The gold nanorods, synthesized using the seed-mediated method, were first coated with dextran sulfate. The dextran sulfate coating changed the local refractive index, which was observed as a red shift in the longitudinal plasmon band. After the addition of 8 μM concanavalin-A, gold nanorod aggregates were formed as shown by TEM analysis. The corresponding UV-Vis spectrum peak wavelength showed a red shift from 701 nm of dextran sulfate coated gold nanorods to 718 nm of concanavalin-A promoted gold nanorod aggregates. The gold nanorod aggregates were dissociated when 12 mM glucose was introduced, as illustrated by TEM images. The longitudinal plasmon resonance of the UV-Vis spectrum also showed a blue shift from 718 nm of dextran sulfate-coated gold nanorods associated by concanavalin-A to 714 nm of dissociated dextran sulfate-coated gold nanorods. The degree of the spectrum peak wavelength shift of the dextran sulfate-coated gold nanorods associated by concanavalin-A can be modulated using glucose ranging from 1 to 30 mM

Synthesis, structural and magnetic properties of TM22+[MOIV(CN)(8)]center dot nH(2)O

Octacyanomolybdates (OCMs) TM2 divided by[Mo(CN)(8)]center dot nHO, where TM is Mn, Fe, Co, Ni, Cu were synthesised and characterised by IR spectroscopy and UV-VIS spectroscopy. The UV-VIS spectrum showed the intervalence charge transfer (IVCT) band between Mo-IV-CN-Cu-II and Mo-V-CN-Cu-I around 510 nm. Studied OCMs adopt tetragonal crystal structure. The H-1 NMR signals reflect the magnetic moment of the TM2- ions (mu(P)). The decay rates of free induction decay (FID) signals increase as pp and the applied static rf-field increases. The spin-lattice relaxation times at 27.7 MHz vary from 0.0187 ins (Mn) up to 0.45 ms (Cu). Magnetization measurements indicate long-range magnetic ordering of Mn- and Co- OCMs with the Curie temperature T-c = 4 K. The remaining OCMs (TM is Fe, Ni, Cu) are paramagnetic down to T = 1.9 K

Geometrical, electronic structure, nonlinear optical and spectroscopic investigations of 4-(phenylthio)phthalonitrile dye sensitizer for solar cells using quantum chemical calculations

The geometries, electronic structures, polarizabilities, and hyperpolarizabilities of organic dye sensitizer 4-(phenylthio)phthalonitrile were studied based on Density Functional Theory (DFT) using the hybrid functional B3LYP. Ultraviolet-Visible (UV-Vis) spectrum was investigated by using a hybrid method which combines CIS-DFT (B3LYP). The absorption bands are assigned to n→π* transitions. The results were showed 4-(phenylthio) phthalonitrile used in Dye Sensitized Solar Cells (DSSC) give a good conversion efficiency