In this paper we proposed an equation system describing resonance stimulated and spontaneous Raman scattering in view of the impact of optical radiation on the population of the energy levels of scattering centers. The dependence of the contribution of the resonant transition in the Raman gain coefficient on the mismatch of resonance is analyzed in the simplest case.

We investigated the exciton spectra of luminescence of ZnO crystals within the temperature interval 10–300 K. In a number of zinc oxide samples at temperatures above 150 K there is anomalous behavior of the temperature characteristics of the exciton-phonon luminescence (EPL) of free excitons, which can be interpreted as a manifestation of the exciton-electron interaction. The features of the temperature behavior of the EPL of free excitons are closely related to the defective composition and total disturbance of the translational symmetry of crystals, which allows us to offer a non-destructive method for their quality control. We described the conditions for registration of an unusual luminescence spectrum of ZnO associated with inelastic scattering of free excitons accompanied by the radiation of excited excitons and exciton-phonon complexes.

We made a comparative investigation of the defective structure of nominally pure congruent and stoichiometric LiNbO₃ crystals as well as a set of congruent magnesium doped crystals within the concentration range 0.19—5.91 mol.% MgO including two concentration thresholds of 3.0 and ~5.5 mol.% MgO. We detected that in the IR absorption spectrum the main band parameters (frequency, half-width, and intensity), related to the valence vibrations of OH groups, near the concentration threshold at 5.5 mol.% MgO display abrupt changes. It is established that the blue shift of the band of the valence vibrations of OH-groups on 50 cm^-1 takes place owing to the Mg_Li⁺-Mg_Nb^3--ОН^- complex formation when the Mg concentration achieves the second concentration threshold.

We investigate the photoconductive and photovoltaic properties of film composites based on poly-N-epoxypropyl-carbazole with additives of new merocyanine dyes – derivatives of fluoren. It is established that these composites have the hole type of photoconductivity, and their internal photoeffect is determined by the photogeneration of charge carriers from the dye molecules and the transfer of the holes to the donor fragments of the polymer matrix in accordance with the jump conduction type. We conclude that the photovoltaic response increases upon application of new dyes the electronic structure of which is close to the structure of an ideal polymenine.

We study the silica gel-glasses obtained by vitrification in air or in a gas mixture of H₂:Ar xerogels doped with Sm, Al, and Ba. It is found that during their synthesis it is possible to form impurity hexagonal and tetragonal crystallites of SiO₂ and tetragonal crystallites of SmSi₂. When the reducing synthesis conditions are applied, the incorporation of samarium in glass simultaneously in two oxidation states (3+ and 2+) takes place. Meanwhile, Sm-Al-containing glasses provide a sufficiently effective sensitization of the luminescence of Sm²⁺ ions by Sm³⁺ ions, while in Sm-Al-Ва-containing glasses this effect is absent because Sm²⁺ ions are localized mainly in the glass sublattice formed with the participation of Ba²⁺ ions. Based on the spectra obtained, the positions of the energy states of the Sm²⁺ and Sm³⁺ ions in such glasses are calculated.

We investigated the absorption spectra of (N(C₂H₅)₄)₂CoCl₂Br₂ (TEACCB-2) crystals and determined the parameters of their structure. The absorption bands related to the internal electronic transitions in the Co²⁺ ion were identified. The impact of phase transitions on the temperature evolution of the absorption spectra was studied. It was shown that the low-energy “tail” of the absorption edge in this material, formed with the participation of the “ligand-metal” charge-transfer electron transitions, possessed an exponential shape which was described by the empirical Urbach’s rule in the two high-temperature crystal phases. On the basis of the analysis of the temperature changes of the main characteristics of the obtained spectra we corrected the temperatures and the phase transition type at T₁ = 244 K and T₂ = 228 K (in the cooling regime). Besides, for the first time an anomaly was detected at the temperature T₃ = 200 K in TEACCB-2 bulk crystals, which was previously observed in the absorption spectrum of TEACCB-2 nanocrystals. This anomaly can be attributed to the phase transition.

We study the mechanisms of formation of the optical center with a zero-phonon line (ZPL) at 580 nm (H19 center) displayed in the photoluminescence (PL) spectra of neutron-irradiated or ion-implanted natural and chemical vapor-deposited diamonds after their high-temperature vacuum annealing. It is shown that the amplitude of the H19 center band at 580 nm increases exponentially with increasing the annealing temperature. From studying the PL spectra temperature dependence and the effects of local mechanical stresses on the position and full width at half maximum of the ZPL peak at 580 nm and its phonon wing one can conclude that the H19 optical center is a complex intrinsic vacancy defect.

Optical properties of spherical metal-oxide nanoparticles are studied in the framework of the Drude theory. The frequency dependences of the real and imaginary parts of the dielectric constant, the coherence loss parameter and the absorption coefficient of two-layer Ag, Al, Cu nanoparticles with a radius of 10–30 nm in different matrices are calculated. It is found that the behavior of the frequency dependences of the imaginary part of the dielectric constant and the absorption coefficient in the low-frequency region is determined by the contribution of the electron surface scattering mechanisms.

The possibilities of spectroscopy in a multilayer cell with a rarefied gas medium are theoretically investigated, when this cell can be used as a compact analogue of a large number of plane-parallel beams of atoms (or molecules) on the optically excited quantum level. Such a situation is realized, in particular, for metastable and also highly excited long-lived Rydberg states of atoms and molecules. The efficiency of the velocity selection of atoms (molecules) on a similar quantum level excited by broadband optical pumping, due to their characteristic transit and collisional relaxation in the cell under consideration, is established. As a result of this selection, narrow sub-Doppler resonances arise at the frequencies of optical transitions from a given level in the absorption of a probe monochromatic light beam.

The interaction of two gold(III) complexes [Au(phen)Cl₂](Cl) (1) and [Au(pdon)Cl₂](Cl) (2) with calf thymus-DNA (CT-DNA) has been investigated by absorption and fluorescence emission. Both complexes 1 and 2 show medium interaction ability with CT-DNA with the intrinsic binding constants K_b of 4.98×10⁵ and 1.98×10⁵ M^-1 at room temperature, respectively, which is the same as earlier reports for typical classical intercalators. Moreover, complex 1 demonstrates a better antitumor effect on the tested cancer cells.

A diffuse reflectance visible light spectroscopy method has been developed to estimate bovine cartilage thickness in real time. The system consists of a miniature UV-VIS spectrometer, a halogen tungsten light source, and an optical fiber probe including two 400 μm diameter fibers with a center to center separation of 1.2 mm was used to acquire the spectra. A total of four patellae obtained from bovine just after sacrifice. In the study, ten cattle patella cartilage samples were prepared in a cylindrical shape and thinned by a 200 µm step. Spectra were acquired from the 123 cartilage samples. Cartilage samples were divided into training and validation groups. A correlation between the thickness of the cartilage samples and the absorption spectra was obtained using the data of the training group. The relative thickness of the cartilage was estimated with an average error of 15% in the validation group using the correlation. Diffuse reflectance spectroscopy has the potential to estimate the thickness of cartilage lesions during arthroscopic evaluation of knee cartilages.

A novel UV spectrophotometric method has been developed for the determination of thiamphenicol in a solid dosage form. The spectrophotometric detection was carried out at an absorption maximum wavelength of 224 nm using water as solvent. The method was validated for specificity, linearity, precision, accuracy, robustness, and limit of detection (LOD) and limit of quantitation (LOQ). The detector response for thiamphenicol was linear in the selected concentration range of 5 to 25 µg/ml with a correlation coefficient of 0.9975. The precision (RSD) among six sample preparations was 0.65 and 1.50 % for analysts 1 and 2, respectively. The average recovery was 99.91 ± 0.65%. The LOD and LOQ were respectively 0.59 and 1.99 µg/ml. The results demonstrated that the excipients in thiamphenicol soft capsules did not interfere with the spectrophotometric determination of the drug. Using the Youden and Steiner approach, the method proved to be robust. The proposed method can be conveniently employed for routine analysis of thiamphenicol in bulk drug and soft capsules.

The effect of 2-hexadecenal on the formation of reactive oxygen and chlorine species (ROCS) in neutrophils stimulated to phagocytosis has been determined by chemiluminescent method. It has been established that at low concentrations this aldehyde demonstrates a priming effect on the cells, enhancing ROCS production, and at higher concentrations – significantly suppresses this process. Comparison the results of chemiluminescent and fluorescent analysis of the cell characteristics suggests that 2-hexadecenal is a signaling molecule, which exhibits the properties of the neutrophil function regulator by modifying the processes of intracellular signaling associated with changes in ROCS production, cytoskeleton reorganization, increase in unbound calcium ions levels in cytoplasm, reduction of mitochondrial membrane potential. It also induces apoptosis.

The objective of this study was to evaluate the influence of partly aqueous solvent mixtures on the solubility and azohydrazone equilibrium processes for a group of phenylazohydroxynaphthalenes, AZ-01, AZ-02, AZ-03, and AZ-04, whose applications as potential color additives and chemosensors have been demonstrated in previous studies. The UV-visible spectrum was acquired between 190-900 nm at concentrations of the dyes that precluded molecular aggregation for each dye in aqueous dimethylformamide and dimethylsulfoxide binary mixtures of varying compositions. The plots of E₁₂ against mole fractions of the co-solvent showed deviation from ideality in the behaviors of the four dyes in the aqueous solvent mixtures. The solvation data were largely influenced by the structural chemistry of the dyes. In particular, AZ-01, which contains a free parahydroxyl group that can donate hydrogen to hydrogen bond acceptor solvents showed substantial bathochromic shifts in the aqueous DMF and DMSO mixtures as well as a local accumulation of the organic solvent in its solvation sphere. Conversely, the positional isomer AZ-02 with its ortho hydroxyl group being involved in intramolecular hydrazone rearrangement exhibited dielectric enrichment in both aqueous solvent mixtures. In addition, synergism through formation of the water-DMSO and water-DMF complexes was observed with all the dyes in the solvent mixtures with AZ-01 being solvated by the more polar component of the complex while AZ-02 and AZ-04 were solvated by the less polar solvent mixture component. Thus, the preferential solvation of the phenylazohydroxynaphthalene series from AZ-01 to AZ-04 in the partly aqueous DMSO and DMF solvent mixtures has been successfully studied using UV-visible spectroscopy.

The method and algorithm for ozone total column (OTC) determining based on spectroscopic measurements of outgoing thermal radiation by IKFS-2 spectrometer (on-board “Meteor-M2 N 2” satellite) are described. Algorithm is based on an artificial neural network method and OMI satellite measurements. The results of comparison of OTC measurements by IKFS-2 spectrometer and by ground-based instruments (Dobson, Brewer, and M-124 ozonometer) are given. It is shown that systematic discrepancy between satellite and ground-based measurements in most cases is not higher than 1%, RMSD values are within 3.0–4.5%. The empirical assessment of retrieval errors demonstrates that Dobson and Brewer OTC measurement random total errors are 1% (in direct solar radiation measurements mode), OMI and IKFS-2 satellite measurements give 2.8 and 3.6% random errors, respectively.

Near-infrared spectroscopy (NIRS) is an effective and efficient technique for evaluating coal quality. The original spectra might be contaminated by scattering interference and random noise. We propose a novel artifact removal framework to recover the buried information and to overcome limitations of currently available pre-processing techniques, such as the multiplicative scatter correction (MSC), as well as a smoothing process. The two-step framework is mainly constructed by MSC and Savitzky-Golay convolution (S-SGC).Moreover, a particle swarm optimization (PSO) algorithm is used to search the optimal parameters within the framework. In addition, the spectra are collected from coal samples with different particle sizes (i.e., 0.2 and 3 mm), which may carry different characteristics and interfering information. We have analyzed seven kinds of coal properties, such as moisture (%), ash (%), volatile matter (%), and heating value (MJ/kg) via partial least square regression (PLSR) models in order to verify the effectiveness of the proposed method. The results show that the proposed two-step method provides superior performances for zooming in the spectral characteristic peaks and filtering the random noise simultaneously, which mainly benefits from the appropriate combination of MSC and S-SGC.

Investigations were initiated for developing a rapid and non-destructive detection method to measure the illegal additive of melamine into milk powder by using terahertz (THz) spectroscopy and the correlation analysis algorithm. The absorption coefficients exhibited a maximum absorption peak at 2.04 THz, which would normally increase along with the concentration of melamine additive. In the current study, correlation analysis was carried out to select a pair-variable at 2.04 and 2.34 THz for improving the predictive ability of the multiple linear regressions (MLR) model. Compared with the partial least square (PLS) model in full spectrum, the MLR model for powder samples could be considered successful in terms of quality control of milk powder with correlation coefficient (R²) of 0.97 and root mean square error of prediction (RMSEP) of 1.38%. At the same time, the MLR model was simple and easier to interpret than the PLS one. The results of the research suggested that THz spectroscopy in combination with the correlation analysis algorithm has a significant potential in the quantitative analysis of the illegal additive of melamine in milk powder.

It was established that quercetin and rutin during sorption on alumina form colored chelate complexes with alumina surface groups, similar to complexes with Al (III) ions in solution. The optical density of the aluminum oxide dispersion in the presence of these hydroxyflavones is maximum in a neutral environment and linearly depends on their concentration in the initial solution. The conditional molar absorption coefficients of surface quercetin (ε^S₄₃₄ = 4386 g·mole^–1 cm^–1) and rutin (ε^S₄₀₃ = 5280 g·mole^–1 cm^–1) complexes were determined. It is shown that highly dispersed aluminum oxide can be proposed as a solid-phase reagent for the determination of quercetin and rutin in the preparations of medicinal plants by the spectrophotometric or visual test method.

Spectrometers with a diffraction grating of the visible and near IR range have a feature that consists in superimposing a spectrum of the second diffraction order on the first. This leads to distortions of the recorded spectrum in its long-wave region. A second-order diffraction correction method is proposed, based on the representation of the spectrum as the sum of Gauss functions, the parameters of which are determined experimentally for individual wavelengths with subsequent numerical interpolation. Parameterization of the line shape in the second order is also used. The details of the required experiment are described and the method is tested on the example of the SSP-600N spectrometer.

The linear algorithm for analysis of variable-frequency phase shift dependencies measured by the frequency-domain method is considered. The analysis is performed in terms of a multi-exponential model adapted for frequency domain. The algorithm is based on the linearization of the model with respect to the coefficients depending on the estimated parameters, and subsequent application of the linear weighted least squares method. The accuracy of the obtained parameter estimations depends on the way of determining the involved weighting factors. Comparative testing of the algorithm with several ways for calculating the weighting factors is done, the reasons affecting their quality were investigated. An approach for calculating weighting factors is proposed that increases the efficiency of the algorithm.

The radiating characteristics of high-current short-arc pulsed discharges in xenon have been investigated at operating voltages from 0.5 to 2.0 kV, discharge energies from 0.25 to 8.0 J, xenon pressures of 4.0 and 6.5 atm, and interelectrode distance of 4 and 6 mm. High radiation fluxes are obtained in the spectral range 200–300 nm corresponding to a bactericidal effect, which allows us to consider the short-arc xenon lamp as a promising source of UV radiation for use in bactericidal devices for various purposes.

The chemical composition of Pr³⁺-doped strontium-aluminum-bismuth-borate glasses with different concentrations, that is, (50 - x)B₂O₃ + 20Bi₂O₃ + 7AlF₃ + 8SrO + 15SrF₂ + xPr₂(CO₃)₃ (where x = 0.1, 0.5, 1.0, and 1.5 mol.%), have been prepared by the melt quenching technique. XRD, SEM, and EDS studies reveal the structural and amorphous properties of the prepared glasses. Different borate groups are analyzed by FTIR measurements. Judd-Ofelt (J-O) intensity parameters, Ω_λ(λ = 2, 4, and 6) are calculated from the absorption spectrum to identify the nature of Pr³⁺ ions with their surrounding ligands. Using the J-O parameters, the radiative properties such as radiative transition probabilities (A_R) and radiative lifetimes (τ_cal) are evaluated for various excited transitions of Pr³⁺ ions. Stimulated emission cross-sections (σ_p^E) and branching ratios (β_R) for the emission transitions are evaluated by the photoluminescence spectra. The higher values of σ_p^Eand β_R are identified for the emission transitions ³P₀→³H₄ and ¹D₂→³H₄ of SABiBPr15 and SABiBPr01 glasses; these glasses are suitable for light emitting materials. The chromaticity color coordinates are calculated to find the average color of the emission spectra.

The Faraday rotation and magnetic circular dichroism (MCD) in media containing spherical layered nanoparticles with a ferromagnetic core and a plasmon shell or two-particle clusters consisting of ferro-magnetic and plasmonic nanoparticles are studied theoretically. For these systems, in the quasistatic approximation of electrodynamics, calculations of the optical absorption spectra, the MCD spectra, the orientation angle of the polarization ellipse, and the ellipticity of the light wave are carried out. It is shown that the magneto-optical response of media with magnetoplasmon inclusions depends on the size of the ferromagnetic component of the inclusion. Moreover, this dependence is more pronounced for bilayer particles, and the response in the region of plasmon resonance of the noble metal is greater than for two-particle clusters.

The optimal geometry, vibrational spectrum and wave functions of 33 oxyanion complexes HOH…A⁻ are calculated by the density functional theory method in the M06-2X/6-311++G(d, p) approximation. The QTAIM analysis of the topological characteristics of the electron density distribution at the critical point (3, –1) on the O...H bond line of oxyanions with a water molecule has been performed. The parametric dependence of the frequency shift ν(OH) has been obtained for the water molecules having H-bond with the anion, which takes into account both the local electron density, and the density of kinetic, potential and total electron energies.

The possibility of using a simplified expression of the kinetic energy operator in generalized coordinates when solving quantum chemical problems for large molecules is shown.

The surface structure and cathodoluminescence (CL) spectra of thin Y₂O₃:Eu and Gd₂O₃:Eu films obtained by RF sputtering have been investigated. Based on the shape analysis of the CL spectra, the possibility of creating irregular solutions of oxides of yttrium and europium, gadolinium and europium in the corresponding films is shown. It has been established that Eu³⁺ ions more uniformly replace Gd³⁺ ions in the Gd₂O₃:Eu cubic lattice with respect to the substitution of Eu³⁺ ions for Y³⁺ ions in the Y₂O₃ cubic lattice.

We have disclosed the synthesis of pyranoquinoline derivatives via a one-pot reaction of 4-nitrobenzaldehyde, malononitrile/ethyl cyanoacetate and 8-hydroxyquinoline using 30 mol.% DMAP in ethanol under reflux conditions. The Fourier transform infrared spectra of ethyl 2-amino-4-(4-nitrophenyl)-4H-pyrano[3,2-h]quinoline-3-carboxylate were recorded within the range 4000-400 cm^{- 1} . The Hartree-Fock and density functional theory on the 6-311G basis set have been utilized to calculate molecular geometry, vibrational frequencies, atomic charges and thermodynamic parameters. Further, the vibrational energy distribution analysis program was applied to assign the vibrational wavenumbers based on potential energy distribution. The HOMO-LUMO energies, the temperature dependence of the thermodynamic properties and the total electron density, and molecular electrostatic potential maps are also studied.

This paper reports a novel way for the synthesis of Ge doped ZnO particles by a mechanically milled Ge and ZnO powder mixture (ZnO:Ge) followed by thermal annealing in Ar + 5%H₂ to achieve near-band-edge (NBE) emission of ZnO with controllable intensities. The Ge doped ZnO particles were synthesized by mechanical milling of a ZnO and Ge powder mixture up to 50 h in particularly, using different ZnO:Ge ratios and annealing temperatures. The Ge doped ZnO particles were observed to have a rounded morphology with a diameter of ~500 nm when an annealing temperature of 1000^oC was used. The Ge doped ZnO particles showed NBE emission of ~380 nm with a suppressed visible band of ~500 nm as a function of the Ge content and annealing temperatures. These results suggest that the current method is very useful for synthesis of Ge doped ZnO particles to obtain NBE emission, which is of particular importance for potential application in the optoelectronic and UV detector field.

The resolving power of spectrophotometric assisted mathematical techniques was demonstrated for the simultaneous determination of the challenging ternary mixture of paracetamol (PAR), orphenadrine citrate (Or.cit) and caffeine (CAF), where PAR, which has the highest absorptivity, is formulated in a very high concentration compared with Or.cit and CAF. Simultaneous area ratio subtraction (SARS), derivative spectrophotometry (D), constant multiplication (CM), and dual wavelength resolution techniques (DW) were able to resolve the three drugs. In SARS, PAR concentration was determined directly at 304 nm in the division spectra using PAR normalized spectrum as a divisor. After subtraction of the constant and multiplying by PAR normalized spectrum; CAF and Or.cit can be determined by first and fourth derivative methods, respectively, from the division spectra. Also, Or.cit and CAF can be obtained by the DW method and CM method, respectively, upon the division of the obtained ratio spectra by CAF spectrum. The proposed methods were validated with good accuracy and precision over the concentration ranges of 20-90, 3-40 and 1-20 mg/mL for PAR, Or.cit, and CAF, respectively. Specificity of the proposed methods was assessed by analyzing laboratory prepared mixtures containing different ratios of the cited drugs. The proposed methods were applied successfully for the determination of PAR, Or.cit, and CAF in their dosage form without any interference.

Four simple, precise, low-cost, sensitive, and diversely applicable UV-Vis spectrophotometric methods have been developed for the assay of dexmedetomidine hydrochloride in pure and pharmaceutical dosage forms. The methods are based on the oxidation of the drug by N-bromosuccinimide (NBS) (excess) at room temperature and estimating the amount of unconsumed NBS by amaranth dye at λ_max = 530 nm (method A), safranin dye at λ_max = 530 nm (method B), aniline blue at λ_max = 610 nm (method C), or rhodamine B at λ_max = 560 nm (method D). Regression analysis of Beer-Lambert’s plots proves excellent correlation in the concentration ranges 2-9, 4-11, 2-10, and 1.2-3.5 μg/ml for methods A, B, C, and D, respectively. The apparent molar absorptivity, Sandell’s sensitivity, and detection and quantification limits are calculated. The proposed methods can be applied to drug formulation and recommended for routine analysis in quality control laboratories. Statistical comparison of the results with the reference method shows excellent agreement.

Herein, the interaction between gliclazide (GCZ) and pepsin (PEP) was explored under simulated physiological conditions by multiple spectroscopy methods and molecular docking. The results showed that a new complex of 1:1 was formed between GCZ and PEP, thereby quenching the endogenous fluorescence of PEP. The addition of GCZ changed the conformation of PEP and increased the α-helix content in PEP from 20.16% to 21.13%. Using the binding constant K_a of the reaction between GCZ and PEP and the number of binding sites n, the binding rate formulas of GCZ and PEP were deduced. It was estimated that when the patient takes 40 mg of GCZ, the PEP in the gastric juice will be reduced by 96.69%. That meant taking GCZ will seriously affect the patient's digestive function. The results of molecular docking indicated that the GCZ binding site was located in the active center of PEP. The interaction of the two was driven by electrostatic attraction and hydrogen bonding forces.

The interaction of nicotinic acid (Nic) and picolinic acid (Pic), as two pyridine carboxylic acids, with human serum albumin (HSA) as a major transport protein in the blood was investigated using UV-Vis, fluorimetry, circular dichroism (CD), and molecular docking studies. The melting point (T_m) and ΔG⁰_(298K) of HSA, as two thermodynamic parameters, were obtained from thermal denaturation of HSA with and without the presence of Nic and Pic. T_m values of 332.5, 336.4, and 333.9 K, and ΔG⁰_298K of 97.4, 99.9, and 118.9 kJ/mol were recorded for HSA alone and following incubation with Nic and Pic, respectively. In chemical denaturation experiments utilizing guanidine hydrochloride (GuHcl), value of ΔG⁰_H2O of 12.5, 16, and 15.3 kJ/mol, [Ligand]_1/2 of 2.2, 2.4, and 2.3 M, and m of 5.6, 6.6, and 6.6 kJ/(mol × M) were recorded, respectively. The results of CD, UV-Vis spectroscopy, and molecular dynamics (MD) simulations showed that the binding of Nic and Pic to HSA induced conformational changes in HSA. Furthermore, the study of molecular docking indicated that the binding affinity of the Nic and Pic to site І (subdomain ІІA) is greater than that of site ІI (subdomain ІІIA) of HSA. These results provide valuable insights into the binding mechanisms of Nic and Pic to a plasma protein that is known to play an important role in the delivery of drugs to target organs.

Spectroscopy has been applied in monitoring soil nutrient concentrations. Two types of soil samples, sandy loam and silty loam, were selected as the research objects. The UV-visible-near infrared reflectance spectroscopy data and total carbon (TC), total nitrogen (TN), total phosphorus (TP), total potassium (TK), available nitrogen (AN), available phosphorus (AP), available potassium (FK), and slowly available potassium (SK) concentrations were measured. We compared the prediction results within and between two different types of soil with regard to the soil nutrient concentrations using four modelling methods, which were principal component regression (PCR), partial least squares regression (PLSR), least squares support vector machine (LS-SVM), and back propagation neural network (BPNN) models. In the prediction results within a given type of soil, LS-SVM and PLSR had better stability. In the prediction results of different types of soil, BPNN and LS-SVM had a high accuracy in most soil nutrient concentrations. By comparing different modelling methods, this study provides a basis for the subsequent selection of suitable models based on spectral technology to establish various soil nutrient models.