NIR PL Spectra

The NIR emission spectra of samples with a fixed Dy2S3 concentration at 0.025 mol% and an increasing Tm2S3 concentration from 0 mol% to 0.15 mol% are shown in Fig. 6.9, while those with a fixed Tm2S3 concentration (0.1 mol%) and varying Dy2S3 concentrations from 0 mol% to 0.05 mol% in are shown in Fig. 6.10. 

It Is seen from Fig. 6.9 that with a pump excitation at 808 nm there Is no obvious emission observed for the single-doped Dy sample (Gl), which is consistent with its absorption spectrum in Fig. 6.8. For codoped samples G2-G7, however, a strong Dy emission at 1,330 nm ( Fn/2+ Hg/2 appears, and it becomes stronger 

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The incorporation of metallic NPs in RE-doped glasses has been intensively investigated in recent years for its positive effects on the PL behaviors of RE ions. Among various RE ions, the trivalent thulium ion exhibits rich emissions from visible bands to the mid-lR region, and its absorption band for the H4 state at 0.8 pm facilitates the use of the commercial GaAlAs diode laser as a pump source. In the present work, the NIR PL spectra of the Tm -doped 70GeS2-... 

The particle size and composition of the dispersed phase of the colloidal dispersions were studied by transmission electron microscopy (TEM), X-ray diffraction (XRD), UV-vis and photoluminescence (PL) spectroscopy. The TEM experiments were carried out on a LEO-906 device. The samples were obtained by placing a drop of the colloidal solution in toluene on TEM copper grid coated with a thin layer of carbon and evaporated in air at room temperature. XRD patterns of powders were obtained by a diffractometer HZG 4A using CuKa radiation. The UV-vis spectra of the colloidal dispersions were recorded using Cary 500 Scan UV-VIS-NIR spectrophotometer with a 1-cm quartz cell. The PL spectra were recorded using a SFL-1211A spectrofluorimeter. 

Spectral and Predictive Variance Captured by Successive PLS Factors for Determination of Oil in Corn Flour Samples. The NIR Reflection Spectra Were Pretreated by MSC and Mean Centering... 

Again using the same structural modification approach, the Cambridge group [768] synthesized the CN-thiophene derivative shown in Fig. 6-1 la. This very low bandgap material displayed the absorption, EL and PL spectra shown in Fig. 16-1 lb. and emitted well into the NIR, up to ca. 1000 nm. This CP, whose LUMO lay closer to the Fermi level of Ca than of Al, functioned well only with the former metal, in the... 

In the majority of quantitative problems, as most in food chemistry are, calibration models are constructed for a large number of parameters, for example near-infrared (NIR), fluorescence spectra or chromatographic profiles. Such parameters are highly correlated and their effective modelling requires the use of latent variables. Partial least squares (PLS) regression is one of the most popular multivariate modelling techniques that can deal with the multicoUinearity problem. The classic PLS model can be presented mathematically as ... 

If an MLR equation needs more than five wavelengths, it is often better to apply one of the other multivariate algorithms mentioned above. Since the information which an analyst seeks is spread throughout the sample, methods such as PLS and PCA use much or all of the NIR spectra to determine the information sought. 

In order to chemically analyse a sample of com for its protein content, a rather complex analytical procedure (e.g. Kjeldahl analysis) is required, a slow and expensive process. In our example, the PCR/PLS group of methods replaces this procedure with a much faster spectroscopic analysis. First, a mathematical relationship is established from a calibration set, comprising a matrix of NIR-spectra of the collection of samples and the vector of... 

Quinn et al. followed the reaction of a nucleoside with trityl chloride in pyridine at 50 °C on the laboratory scale. This reaction is the first step of an industrially significant process. The UV-vis spectra were analyzed with chemometric analysis where automatic window factor analysis (WFA) yielded better results than PLS. A reactive intermediate, a solvated carbocation, was identified that had not been found with HPLC (quenching upon aliquot dilution) or NIR, respectively. Small, sudden process upsets could be detected. 

The total solid (dry matter) content of potato can be obtained by freeze-drying. Dry matter content is determined from the difference in the weight of potato samples before and after freeze-drying. The potato dry matter can also be estimated from the specific gravity measurements. In recent years, near infrared (NIR) spectroscopy has been used to measure specific gravity of potatoes. The NIR spectra (700-1100 nm) of potato samples are acquired, and partial least squares (PLS) regression analysis can be used to develop a predictive model for specific gravity (Scanlon et al., 1999). 

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