The density functional theory PBE/TZVP calculations of the geometric structures in the ground singlet state S₀ and the first excited triplet state T₁ have been carried out for molecules of Mg pheophorbide a (MgPhe) (i.e., for chlorophyll α, devoid the phytol “tail”), Mg bacteriopheophorbide α (MgBPhe), as well as Mg chlorin (MgC) and Mg bacteriochlorin (MgBC). It follows from the comparison of the bond lengths for MgC-MgPhe and MgBC-MgBPhe pairs that the central macrocycle of the first pair is more unstable to “splittings” of equivalent bond lengths both as a result of the S₀→T₁ transition and as the molecular structure becomes more complex (mainly due to cyclopentanone ring V formation). It is found that the symmetry of MgC in the T₁ state decreases as compared to the C_2v symmetry in the S₀ state while MgBC has the D_2h symmetry in both states. These peculiarities can relate to that in whole the central n system of the MgC-MgPhe pair is antiaromatic (contains 24 electrons which corresponds to the Htickel 4n rule), and the central n system of the MgBC-MgBPhe pair is aromatic (consists of 22 electrons and satisfies the Htickel 4n+2 rule). The energies of the T₁ state of the molecules studied are calculated. For MgPhe the computed values of E _T1 are 11400, 10850, and 10200 cm^-1 for the vertical S₀→T₁ transition, taking into account the optimization in the geometry in the T1 state and additionally taking into account the changes of the zeropoint vibrations at S₀→T₁ transition, respectively, that is in very good agreement with the experimental value of 10310 cm^-1 (for chlorophyll a). For MgBPhe, the corresponding calculated values ET1 are 8350, 8100, 7700 cm^-1, while the experimental one is 8190 cm^-1 (for bacteriochlorophyll α).

Room-temperature absorption by PH₃-H₂ mixtures in the ν₂ and ν₄ bands of phosphine (PH₃) has been measured for low pressures. Fits of these spectra are made to determine the width of isolated lines and line mixing in a first-order Rosenkranz approximation. From the previous determinations, we deduce remarks on the lack of accuracy of predicting the collisional process. With the first-order Rosenkranz approximation, the collisional parameters are considered linear with pressure. In this work, we have considered spectra recorded for three doublets: A₁ and A₂ lines in the ν₂ and ν₄ bands of PH₃ diluted with higher H₂ pressure. We show that the line shifts are non-linear with perturber pressures, which requires testing the fits of the recorded spectra with profiles developed in the second-order approximation of the perturbation theory. Consequently, the first- and second-order mixing coefficients are determined and discussed. Throughout this study, we also show that the change in the intensity distribution is provided by the population exchange between low energy levels for the two components of doublets A₁ and A₂ lines and is described through the second-order mixing parameter. Thereby, we show the mixing effect on line width.

The signals of the hydrogen and carbon atoms nuclei of isoxazolinyl steroids, i.e., structural analogs of ponasterone A and 9α,20-dihydroxyecdysone, were assigned by two-dimensional NMR spectroscopy. The characteristic features of neighboring functional groups affecting the chemical shift of carbon and hydrogen atoms in the NMR spectra were revealed. Some data on the spectral characteristics of the previously described compounds were refined.

The influence of the molecular structure of indotricarbocyanine dyes on their spectral luminescent and redox properties has been studied. The introduction of a chloro-orthophenylene bridge into the polymethine chain results in a significant hypsochromic shift of the absorption and fluorescence spectra, whereas a change in the substituents structure at the indolenine terminal groups affects the spectra insignificantly. The electrochemical properties of the polymethine dyes have been studied by cyclic voltammetry. The oxidation and reduction potentials of the dyes have been determined and the corresponding energies of the highest occupied and lowest unoccupied molecular orbitals have been calculated. The reduction of the dye molecules is an irreversible process, whereas the reversibility of the oxidation process depends on the structure of the polymethine chain and the nature of the counterion. The introduction of a chloro-ortophenylene bridge into the polymethine chain leads to a significant increase in the reversibility of the oxidation reaction of dyes due to a growth in the stability of dication-radicals. The oxidation of bromide ions has been shown to occur at smaller values of the potential compared to the oxidation of the dyes with substituted polymethine chain, which probably results in a decrease in the reversibility of the electrochemical oxidation of these dyes in the presence of bromide ions in solution.

The asymmetry of the recorded contours of the absorption lines of water vapor in a quartz tube at room temperature at pressures of 0.03-1 Torr was investigated. The measurements were carried out using the method of diode laser spectroscopy with an external optical cavity. In order to accurately define narrow contours of absorption lines off-axis alignment of the resonator was used. The measurements were carried out with different laser frequency tuning rates of 0.1-0.8 cm^-1/ms with mirrors with 99 and 99.98% reflectivity and different directions of laser frequency tuning. Line asymmetry occurs due to the time delay of radiation inside the cavity. The results of numerical modeling taking into account the filling of the cavity with laser radiation and its decaying in time at the cavity output are in good agreement with the experimental data.

For amorphous carbon there are compared the results of the experiment and calculation of the density of electronic states from the analytical form of the interband absorption spectrum. From the analytical form of the interband absorption spectrum the proportionality coefficient and the energy width of the mobility gap were also determined as adjustable parameters. For the interband absorption spectrum, described by the Davis-Mott approximation method according to the Kubo-Greenwood formula, for the parabolic allowed bands, a new expression is obtained that determines the density of electronic states in the valence band of amorphous semiconductors. Using this formula and the value of the interband absorption spectrum obtained from the experiment for amorphous carbon, the possibility of determining the density of electronic states in the valence band is shown.

The nonlinear equatorial Kerr effect in a planar nanostructure consisting of ferromagnetic and plasmon layers and located between two optically transparent dielectrics is studied theoretically. Calculations are made of nonlinear surface polarizations of interfaces between media that are sources of the second harmonic (SH), angular dependences of the intensities of the reflected SH and magnetic contrasts for different thicknesses of the noble metal layer. It is shown that when a p-polarization wave is incident on the nanostructure, the SH intensity is maximal in the region of the plasmon resonance of the basic frequency on the metal surface adjacent to the lower dielectric. A significant effect of the thickness and location of the plasmon layer on both the SH intensity and the magnetic contrast has been established.

The process of frequency doubling of the first type of interaction (oo-e) of intense short laser pulses in crystals with a regular domain structure has been studied by a numerically. The influences of the dispersion of the group velocity of the medium up to the third order and cubic nonlinearity of the Kerr type on the formation of the second harmonic pulse are analyzed. The case is considered when both the conditions of quasi-phase matching and the synchronism of group velocities are simultaneously satisfied. It is shown that, in this case, an insignificant change in the domain size from the exact value providing the condition of quasiphase matching leads to a significant increase in the efficiency (almost twofold) of second harmonic generation. Calculations show that the latter is due to the mutual compensation of phase shifts caused by the Kerr-type cubic nonlinearity, the dispersion of the medium and the additional value of the wave number of the nonlinear grating. Lithium niobate with a 5% addition of magnesium oxide (5 % MgO:LiNbO₃) was chosen as a periodically polarized crystal, in which it is possible to create the conditions of quasi-phase matching and synchronism of group velocities at a certain wavelength of the main radiation (~1560 nm)

Individual and mixed oxides of Zn, Mg, Si, Ti, modified with L-proline in the process of sol-gel synthesis, has been obtained. The IR spectra, in which changes in the parameters of vibration bands of the siliconoxygen and metal-oxygen bonds are observed after the removal of L-proline, have been studied in detail. The SiO₂-TiO₂ oxide is characterized by an increase in the number of basic centers after the removal of L-proline from the surface. The SiO2-Mg(OH)₂*L-proline composite increases the values of enantiomeric excess of asymmetric Biginelli reaction product up to 18%.

The structures of 7-amino-3-tert-butyl-4-oxo-1,4-dihydropyrazolo[5,1-c][1,2,4]triazin-8-carbonitrile and 8-ethyl carboxylate were studied by X-ray crystal diffraction analysis. Both molecules demonstrate planar conjugated heteronucleus with a marked tendency to formation of intra- and intermolecular hydrogen bonds. The molecular bond length and angles in single crystals were investigated.

We studied the substructures of LiF crystal samples grown by the Kiropoulos and Bridgman-Stockbarger methods. Measurements were made using the double-crystal X-ray diffractometry technique. The peak's angular full width at half maximum (FWHM) was calculated for each diffractogram. Statistical processing of the FWHM measurement data indicates that the samples grown by the Bridgman-Stockbarger method have a smaller angular misorientation of the substructure and include areas suitable for manufacturing crystalline X-ray analyzer blanks of the required size.

We investigated the optical and photocatalytic properties of CdS quantum dots doped with manganese ions. The synthesis of quantum dots was carried out by the colloidal method in the aqueous medium with mercaptoacetic acid as a stabilizer. The optical, dimensional, and paramagnetic properties of the obtained nanoparticles were studied. The photocatalytic properties of the quantum dots were studied via the model reaction of the destruction of rhodamine B. The influence of the manganese ions concentration and the temperature of the reaction mixture on the rate of photodegradation of the dye was studied.

LIBS spectra were obtained for 20 alkali halides using a hand-held instrument. The intensities of the strongest emission lines were determined for Li, Na, K, Rb, Cs, F, Cl, Br, and I, and their corresponding electronic transitions assigned. Halogen peak intensities are observed to be at least two orders of magnitude smaller than those of the alkali metals. Thus, halogens are difficult to detect and identify with certainty. Relative intensity ratios of halogen/alkali metal aid in identification of those non-metals, particularly in mineralogical samples.

The demand to improve the efficiency of precious metal trade has been increasing of late. Due to its non-destructive nature, energy-dispersive X-ray fluorescence has the potential to supplant the fire assay procedure. Improved accuracy in the measurement of gold purity can be achieved by optimizing the X-ray fluorescent signal by selecting a suitable collimator beam size. Four homogenous materials with different alloy matrix of gold-certified reference were investigated. The effects of collimator beam sizes on the accuracy of gold purity evaluation were observed. The findings can be treated as the foundation to improve the accuracy of gold purity measurement with X-ray fluorescence.

Herein, the chlorophyllin effect on the binding of proflavine, doxorubicin, ethidium bromide, and berberine to the DNA was studied by the spectrophotometry technique. For the titration data analysis, the multivariate curve resolution-alternating least squares method (MCR-ALS) was used. The pure spectra of all the absorbing particles in the systems and their concentration profiles were obtained. It was shown that chlorophyllin forms complexes with all the studied ligands. The equilibrium parameters of the ligand interactions with chlorophyllin and the DNA in the binary (ligand-chlorophyllin and ligand-DNA) and ternary (ligand-chlorophyllin-DNA) systems were obtained. It was found that in the presence of chlorophyllin, the number of ligand molecules bound to the DNA decreases. The main reason for this effect is heteroassociation since the calculated values of the constants for the interactions of the ligand with the DNA and chlorophyllin are similar. A comparison of the theoretical isotherms of ligands binding to the DNA in the ternary systems with ones obtained directly from the decomposition data was performed to test the presence of other mechanisms of the chlorophyllin competitive action. It is shown that taking into account only the heteroassociation of ligands is enough when describing the experimental isotherms. The protector action of chlorophyllin is not realized in the studied ternary systems; consequently, chlorophyllin does not interact with the DNA.

It was established that the spectral characteristics (intensity and position of absorption bands) of structurally similar natural cinnamic acids sorbed on the aluminum oxide surface depend on the surface concentration and the pH of aqueous solutions. The conditional molar absorption coefficients (g/(mole•cm)) of adsorbed cinnamic (ε^S_274nm = 1766), coumaric (ε^S_286nm = 2056), ferulic (ε^S_290nm = 1139), and caffeic (ε^S_350nm = = 1163) acids were determined. It was found that the optical density of cinnamic acids correlates with their concentration in the initial testified solution. Owing to this, highly dispersed aluminum oxide can be recommended as a solid-phase reagent for the evaluation of cinnamic, coumaric, ferulic, and caffeic acids in plant-derived products by spectrophotometry or visually test methods. The possibility of selective determination of caffeic acid was also shown.

Herein, a computational platform FluorSimStudio was developed for processing fluorescence decay curves in molecular systems, which implements the concept of complex analysis of experimental information based on the simulation modelling and data mining methods. Data analysis includes partitioning the fluorescence decay curves into clusters according to the degree of likeness to some measure of similarity, finding the median cluster members (medoids), applying the data reduction method and visualizing the experimental data in a two-dimensional space. Analysis of the decay curves is carried out by the analytical or simulation models of optical processes occurring in molecular systems. The visualization of data clusters in the original and transformed time spaces is done with the aim of user interaction. A functional scheme of the platform is proposed, the choice of software for ensuring high computing performance is substantiated, a web application of the platform is implemented (https://dsa-cm.shinyapps.io/FluorSimStudio), and the results of a comparative analysis of the simulation algorithms are presented. The performance of the computational platform was confirmed by examples of the analysis of data sets representing systems of free fluoro-phores and in the presence of the Forster electronic excitation energy transfer process. The computational platform is an open system and allows permanent addition of complex analysis models, taking into account the development of new algorithms for modelling the energy transfer processes in molecular systems, studied with the use of time-resolved fluorescence spectroscopy systems.

The calibration-free laser-induced breakdown spectroscopy (CF-LIBS) method is used to obtain the concentration of the constituents of samples because it overcomes the limitation of matrix-matched standards in the calibration curve method of quantification. However, there are often doubts that remain about the efficiency of the CF-LIBS method. Hence, in the present work, different certified reference materials (CRMs) of plants and soil were employed to check the capabilities of the CF-LIBS method. If the emission lines of an element are missing in the LIBS spectra, its contribution in the CF-LIBS result will be missing as well, which leads to incorrect quantification. Therefore, in order to overcome this problem in CF-LIBS, instead of only determining the elemental concentrations, an additional step to calculate the concentration ratio of all elements with respect to the concentration of a major element was added. The calculated concentration ratios for different elements are more accurate than the elemental concentration obtained by CF-LIBS. Along with the CF-LIBS method, the partial least square regression (PLSR) approach was also applied for the prediction of the concentration.

It is shown that the average distance between the combining electronic states, including ones under magnetically induced circular luminescence, is determined from the diffuse electron-vibrational (vibronic) absorption and emission spectra of the magnetically induced optical activity (MOA) at the thermal equilibrium of the initial states in the transition. It differs significantly from the average distance between the vibronic states combining in the transitions. The difference in the transition mechanisms is reflected in the difference not only in the spectra, but also in the purely electronic transitions of the MOA. The heterogeneity of the ensembles of MOA molecular chromophores is qualitatively manifested in the MOA spectra by the blurring of the indication of a purely electronic transition.

Herein, the spatial-energy profiles (SEPs) of the recorded signal was numerically studied at different shapes of the illumination pulse and ratios between the durations of illumination τ_р and registration τ_g pulses at a fixed delay distance. It was established that at τ_р < τ_g and τ_р = τ_g the characteristic distance of visibility ranges do not depend on the shape of the illumination pulse. For their determination it is possible to use the previously obtained expressions for illumination pulses of a rectangular shape. As a rule, for the cases considered at τ_р > τ_g SEP is a convex asymmetric curve with one maximum in a point S_max. For the simplest forms of illumination pulses designed by triangles or trapezoids the analytical expressions were obtained, allowing calculation of the value S_max on the known delay distance and the duration of the illumination pulse. For the ratio τ_р > τ_g, the method of the calibration constant was also proposed to determine the distance S_max at a real shape of the illumination pulse.

We developed and manufactured a laser atomic emission multichannel spectrometer (LAEMS) with an achromatic optical scheme for research and educational purposes. The new spectrometer fits all the requirements for equipment for laser-induced breakdown spectroscopy and also has a number of advantages due to the design and technical characteristics of its components. As an excitation source, the spectrometer includes two Nd:YAG lasers pumped by semiconductor laser diode arrays, with adjustable energy (from 0 to 100 mJ) and pulse interval (from 1 to 100 ps); the average pulse duration ≈15 ns. LAEMS permits to carry out studies using both single-pulse and double-pulse laser ablation and excitation of emission spectra. Using double pulse laser ablation on LAEMS, a significant (up to 10 times) increase in the analytical signal was recorded, with a slight (1.5-2 times) increase in the surface destruction.

The non-collinear three-fold acoustooptic diffraction of Bessel light beams by ultrasound in uniaxial crystals is investigated. An expression for the complex vector amplitude of a wave diffracted under conditions of exact Bragg synchronism is obtained in the vector-matrix form. It is established that when a Bessel light beam propagates at a small angle to the optical axis of the crystal, the diffracted light beams display three-fold Bragg diffraction with different efficiency. If the conditions of Bragg synchronism are exactly fulfilled, a diffraction case is possible when the diffracted light beams have the same intensity; in the absence of Bragg synchronism, this diffraction feature is not observed. With large frequency detuning of the Bragg synchronism, the light intensity in the third diffraction order is significantly reduced (up to zero).

Herein the energies of low-lying levels, wavelengths, transition rates, and line strengths for electric dipole allowed (E1) and forbidden (M1) lines in Ne- to Al-like ions of tantalum have been calculated using the GRASP2Kpackage, which is based on the multiconfiguration Dirac-Hartree-Fock (MCDHF) method. From our radiative decay rates, we also calculated the radiative lifetimes of some levels. The present results are in good agreement with other available theoretical and experimental values. We predict new data for several levels where no other theoretical and/or experimental results are available, stipulating the necessity of precise measurements.

Chlorophyll content is an important index for monitoring the health status of vegetation growth. Revealing the variation characteristics of the chlorophyll content in leaves of Populus euphratica plays an important role in evaluating the health and ecological conservation of Populus euphratica. In this study, leaves of healthy Populus euphratica and water-stressed Populus euphratica were collected from May to October, and the spectral reflectance was obtained at 390-1100 nm. At the same time, the chlorophyll content of Populus euphratica leaves was analyzed. The results indicated that from May to October, the chlorophyll content showed a trend of “two peaks and two valleys,” which decreased first, then increased and then decreased. In general, the chlorophyll content of healthy Populus euphratica leaves was higher than that of water-stressed Populus eu-phratica leaves. The ratio of chlorophyll a to chlorophyll b was maintained between 3.0 and 3.4 from May to August, while there was a significant increase in September and October. The ratio of chlorophyll a to chlorophyll b in healthy Populus euphratica leaves was significantly lower than that in water-stressed Populus euphratica leaves from June to September. The spectral curves of healthy Populus euphratica leaves were relatively consistent from May to August, and the curves in the near-infrared band were also concentrated. For the water-stressed Populus euphratica leaves, the curve in the near-infrared band was more dispersed. There were two absorption valleys at wavelengths of 500 and 675 nm, and some of the absorption characteristic parameters of the two absorption valleys had a significant correlation with the chlorophyll content. A partial least squares regression model constructed by these absorption parameters roughly estimated the chlorophyll content of the water-stressed Populus euphratica leaves.

The crystal structure of [3-(3-bromophenyl)-cis-4,5-dihydroisoxazole-4,5-diyl]bis(methylene)diacetate (BDBD) was determined using X-ray diffraction data. Hirschfeld surface and fingerprint plots were used to locate and analyze the molecular surface. The optimized molecular structures, frontier molecular orbitals, quantum chemical parameters, and NMR chemical shifts of the investigated compound were calculated with DFT at the B3LYP/6-311G(d,p) level of theory. The experimental NMR of the studied compound was measured in deuterochloroform (CDCl₃) solvent, employing tetramethylsilane as an internal standard. It was established that the experimental and simulated ¹H and ¹³C NMR spectra were in good agreement. Vibrational spectrum analysis was carried out by FT-IR spectroscopy in the range 400-4000 cm^-1 for the title molecule. The vibrationalfrequencies of the investigated compound were calculated with DFT at the B3LYP/6-311G(d,p) level of the theory. The wavenumbers received complete vibrational assignments based on their potential energy distribution. The experimental and simulated FT-IR spectra were in good agreement.

The proximate analysis of coal, which aims to estimate the moisture, volatile matter, and caloric value, is of great importance for coal processing and evaluation. However, traditional methods for proximate analysis in the laboratory are not only time-consuming and labor-intensive but also expensive. The near-infrared spectroscopy (NIRS) technique provides a rapid and nondestructive method for coal proximate analysis. We exploit two regression methods, random forest (RF) and extreme learning machine (ELM), to model the relationships among spectral data and proximate analysis parameters. In addition, given the poor stability and robustness caused by the random selection of parameters in ELM, we employ the particle swarm optimization algorithm (PSO) to optimize the structure of ELM (PSO-ELM). A total of 384 coal samples from Inner Mongolia are collected for model training and validation. The experimental results show that the proposed PSO-ELM algorithm achieves the best performance in terms of accuracy and efficiency, which indicates that NIRS combined with PSO-ELM has significant potential for accurate and rapid proximate analysis.

The nutrient profiling of green leafy vegetables is largely concentrated on biochemical assays and their elemental composition is often overlooked. At the same time, the investigation of the elemental composition of plants is essential, as they are required in several metabolic processes for the normal growth and development of the human body and their deficiency can lead to several clinical disorders. In this paper, we consider the potential of the synchrotron-radiation-induced energy dispersive X-ray fluorescence spectroscopy technique as a rapid, sensitive, and simultaneous multielemental detection tool to investigate the elemental composition of different elements present in some leafy vegetables: dill, fenugreek, mustard, and chenopodium. The X-ray fluorescence spectra of the leaves of dill, fenugreek, mustard, and chenopodium were excited by synchrotron X-ray radiation having an energy of 15 keV and recorded in the energy range <20 keV. The recorded spectrum shows the presence of potassium, calcium, manganese, iron, nickel, copper, zinc, arsenic, and selenium with varying concentrations in different leafy vegetables. PyMca software was applied to determine the concentration of the various detected elements. The relative quantitative comparison of the detected elements shows that chenopodium leaves are a rich source of potassium among all the leafy vegetables studied. The leaves of mustard and chenopodium are abundant in calcium, while the leaves of dill and fenugreek have a higher content of trace elements like manganese, iron, copper, nickel, selenium and zinc. Herein, the role of the detected elements in human and plant health is also described.

We aimed to assess the near infrared spectroscopy as a method for non-invasive on-line detection of hyperglycemia from spent hemodialysis effluent. We used partial least squares regression and several machine learning algorithms: random forest (RF), logistic regression, K-nearest neighbor (KNN), support vector machine (SVM), decision tree classifier, and Gaussian naive Bayes (NB) to classify normoglycemia from hyperglycemia. These classifier methods were used on the same dataset and evaluated by the area under the curve. The serum glucose levels were presented in the form of a binomial variable, where 0 indicated a glucose level within reference range and 1 a glucose level beyond the normal limit. For this reason, the methods of machine learning were applied as more specific methods of classification. RF and SVM have shown the best classification accuracy in predicting hyperglycemia, while decision tree and NB showed average accuracy.

The gas chromatography-mass spectrometry and dielectric spectroscopy techniques are used to characterize the thermodynamic properties of the essential oils extracted from two main Mediterranean wildland fuels, namely eucalyptus leaves and Pinus halepensis needles. These oils are assumed to be representative of the fuels organic volatile components that exhibit different fire behaviors. The relaxation frequencies determined from the peak of the imaginary permittivity spectra using the Havriliak-Negami empirical law revealed the Arrhenius dependence on temperature. Two activation energies are obtained: the first is around 4.13 kJ /mol for both species, and the second activation energy is around 1.27 kJ/mol for the Pinus halepensis essential oil and around 2.15 kJ/mol for the eucalyptus essential oil. Qualitative and quantitative composition differences are observed with GC-MS measurements for eucalyptus leaves and Pinus halepensis needles essential oils.

A reproducible, sensitive, and cost-effective spectrofluorimetric method has been developed for the quantification of azelastine hydrochloride in its bulk and nasal formulations. The stability-indicating potential of the method was assessed by recovery studies in the forced degraded solutions of the drug. The method was validated in accordance with the ICH guidelines with respect to linearity, accuracy, precision, limit of detection (LOD), limit of quantification (LOQ), and robustness. Excellent linearity was noted in the concentration range 2.0-40.0 μg/ml with a correlation coefficient (R²) of 0.9961. The limits of detection and quantitation for the proposed method were found to be 0.1598 μg/ml and 0.4845 μg/ml respectively. Excellent recovery of the drug was obtained from the proposed method in the nasal spray formulation of the drug (96.5, 0.66% RSD). The stability-indicating potential of the method was assessed from recovery studies of the drug from various forced-degraded samples spiked with known drug concentrations. The studies indicated a high rate of degradation in alkaline, oxidative, and photolytic stress degraded solutions.

Application of near-infrared spectroscopy to the prediction of sample content is strongly limited by signal peak overlap. To analyze the spectral information directly related to the target components and to make the chemometric model more explanatory, an independent characteristic projection algorithm is proposed. The algorithm was applied to the independent spectral analysis of a single sample using corn as a representative example. Moisture, oil, protein, and starch, which are the four main components of corn, were the target components. The pure component spectra were used the projection directions to decompose the near-infrared spectrum of a single corn sample; then four decomposed spectra corresponding to the four pure component spectra were obtained. Their corresponding relationship was determined using their correlation coefficients and by comparing their characteristic peaks, and the molecular absorption patterns corresponding to the characteristic absorption peaks of each decomposed spectrum were analyzed in detail. The theoretical analysis and experimental results indicate that the independent characteristic projection algorithm can be applied to single-sample spectral analysis to extract more complete physicochemical information about the target components and provide a theoretical basis for establishing a robust near-infrared spectral chemometric model with great extrapolation capability and stability.

For hyperspectral unmixing, a multi-scale spatial regularization method based on a modified image segmentation algorithm to generate super-pixels is proposed in which the super-pixels are used to extract contextual information from spatial correlations and spectral similarity in hyperspectral images (HSIs). The unmixing problem is decomposed into two simple unmixing subproblems regarding the approximate super-pixels and the original pixels. The unmixing results of these two subproblems have spatial-correlation constraints. Introducing a novel regularization term to constrain the abundance matrix to promote the homogeneous abundances helps in making effective use of the spatial correlations and spectral similarity of the abundances from HSIs. Experimental results obtained from synthetic data demonstrate that the proposed algorithm yields an accuracy greater than other conventional methods.