NIR Range Research Articles

Mushroom-structured silicon metasurface for broadband superabsorption from UV to NIR

Improving the light absorption capacity is essential in some systems that require a high photoelectric conversion efficiency. In this study, a silicon metasurface with mushroom structures is efficiently designed and fabricated based on metal thermal annealing and inductively coupled plasma processes. This metasurface exhibits nearly perfect broadband superabsorption properties across wavelengths in the UV to NIR range. Additionally, the effects of the diameter and height of the mushroom structure on the absorption properties of the silicon metasurface are analyzed by using the finite difference time domain method. Moreover, by carefully adjusting the film thickness and etching time, it is shown that the proposed mushroom-structured metasurface is applicable to systems requiring high absorptance, such as solar cells and photodetectors.

Induced absorption in quartz by picosecond pulse of 8 MeV electrons

The induced transient absorbance in irradiated fused silica could be crucial in analyzing and interpreting the results of pulse radiolysis for weakly absorbing transient species. In this study, we investigated the absorbance of quartz plates in the UV–Vis range in a timescale of 10 ns instead of 1 ns done in the previous study (Schmidhammer et al. (2012)) and we extended it to the NIR range. Herein, we report on the dynamics of radiolytic species induced in fused silica by 7 ps electron pulse (8 MeV). The results infer that at least two main species are induced in the material when subjected to picosecond electron pulse. One kind of species has strong absorption in the UV while the other species have broad absorbance with a maximum at 580 nm. Unlike in the UV and Vis spectral range, a low absorbance is observed also in the NIR, which decays immediately after the pulse within 11 ps. Our finding confirms and suggests that the prevailing induced absorbance in quartz cells should not be neglected when transient species of other solutions are considered in the sub- 10 ns pulse-probe measurements.

Controllable synthesis of hexagonal WO3 nanorod-cluster films with high electrochromic performance in NIR range

Hexagonal WO3 (h-WO3) nanorod-cluster films were controllably synthesized by a facile template-free hydrothermal technique. The pH value and the amount of urea in the precursor have critical influences on the crystal form and morphology of the WO3 film. The obtained uniform WO3 films feature a porous structure of clusters composed of h-WO3 nanorods with diameter of 6–10 nm and length of up to several hundred nanometers. Due to the novel microstructure and crystalline phase, the high electrochromic performance in NIR range with a high optical modulation of 46% in 1600 nm, fast switching speed (2.4 s for coloration and 3.6 s for bleaching), high coloration efficiency (106.1 cm2 C−1 in 1600 nm), and an excellent cycling stability (more than 96% charge capacity retained after 1000 cycles) was achieved.

Magnetic and GRPR-targeted reduced graphene oxide/doxorubicin nanocomposite for dual-targeted chemo-photothermal cancer therapy

Herein, we design a rGO-based magnetic nanocomposite by decorating rGO with citrate-coated magnetic nanoparticles (CMNP). The magnetic rGO (mrGO) was modified by phospholipid-polyethylene glycol to prepare PEGylated mrGO, for conjugating with gastrin-releasing peptide receptor (GRPR)-binding peptide (mrGOG). The anticancer drug doxorubicin (DOX) was bound to mrGO (mrGOG) by π-π stacking for drug delivery triggered by the low pH value in the endosome. The mrGOG showed enhanced photothermal effect under NIR irradiation, endorsing its role for dual targeted DOX delivery. With efficient DOX release in the endosomal environment and heat generation from light absorption in the NIR range, mrGOG/DOX could be used for combination chemo-photothermal therapy after intracellular uptake by cancer cells. We characterized the physico-chemical as well as biological properties of the synthesized nanocomposites. The mrGOG is stable in biological buffer solution, showing high biocompatibility and minimum hemolytic properties. Using U87 glioblastoma cells, we confirmed the magnetic drug targeting effect in vitro for selective cancer cell killing. The peptide ligand-mediated targeted delivery increases the efficiency of intracellular uptake of both nanocomposite and DOX up to ~3 times due to the over-expressed GRPR on U87 surface, leading to higher cytotoxicity. The increased cytotoxicity using mrGOG over mrGO was shown from a decreased IC50 value (0.70 to 0.48 μg/mL) and an increased cell apoptosis rate (19.8% to 47.1%). The IC50 and apoptosis rate changed further to 0.19 μg/mL and 76.8% in combination with NIR laser irradiation, with the photothermal effect supported from upregulation of heat shock protein HSP70 expression. Using U87 tumor xenograft model created in nude mice, we demonstrated that magnetic guidance after intravenous delivery of mrGOG/DOX could significantly reduce tumor size and prolong animal survival over free DOX and non-magnetic guided groups. Augmented with NIR laser treatment for 5 min, the anti-cancer efficacy significantly improves with elevated cell apoptosis and reduced cell proliferation. Together with safety profiles from hematological as well as major organ histological analysis of treated animals, the mrGOG nanocomposite is an effective nanomaterial for combination chemo-photothermal cancer therapy.

Development of Calibration Models to Predict Mean Fibre Diameter in Llama (Lama glama) Fleeces with Near Infrared Spectroscopy.

Simple SummaryIn the Puna region of Argentina, llama fibre production has enormous social, economic and environmental potential, but is still in its early stages of development. For this reason, classification and quality analysis systems used today are still deficient. Near infrared reflectance spectroscopy is a technological resource used in the agroindustry for quality analysis of organic compounds. In this work we studied the feasibility of this technology to evaluate the mean fibre diameter, which is one of the most important quality parameters in the textile industry. Despite some limitations, which are mainly related to fibre heterogeneity, the results obtained were encouraging as spectroscopy could be used in screening programmes as a sustainable, fast and low-cost method to improve fibre quality validation.Llama fibre has the potential to become the most valuable textile resource in the Puna region of Argentina. In this study near infrared reflectance spectroscopy was evaluated to predict the mean fibre diameter in llama fleeces. Analyses between sets of carded and non-carded samples in combination with spectral preprocessing techniques were carried out and a total of 169 spectral signatures of llama samples in Vis and NIR ranges (400–2500 nm) were obtained. Spectral preprocessing consisted in wavelength selection (Vis–NIR, NIR and discrete ranges) and multiplicative and derivative pretreatments; spectra without pretreatments were also included, while modified partial least squares (M-PLS) regression was used to develop prediction models. Predictability was evaluated through R2: standard cross validation error (SECV), external validation error (SEV) and residual predictive value (RPD). A total of 54 calibration models were developed in which the best model (R2 = 0.67; SECV = 1.965; SEV = 2.235 and RPD = 1.91) was obtained in the Vis–NIR range applying the first derivative pretreatment. ANOVA analysis showed differences between carded and non-carded sets and the models obtained could be used in screening programs and contribute to valorisation of llama fibre and sustainable development of textile industry in the Puna territory of Catamarca. The data presented in this paper are a contribution to enhance the scarce information on this subject.

Thickness induced modifications in the valence, conduction bands and optoelectronic properties of undoped and Nb-doped anatase TiO2 thin films

Nb-doped anatase TiO2 (NTO) is a promising wide band gap transparent semiconductor as it is an inexpensive, environment-friendly and chemically stable compound. However, its overall electronic structure and optoelectronic properties are tailored by tuning the microstructure, which are effected by varying process conditions. To this end, here series of thickening NTO and undoped anatase TiO2 (TO) films are deposited on quartz substrate in RF magnetron sputtering, followed by vacuum annealing at 823 K. Following fabrication, detailed electronic structure, defect states, microstructure and optoelectronic characterization of all these films are performed. Here, energy positions of the valence and conduction band edges are correlated with the oxygen and titanium content of these films. Whereas, TO films are found to be highly insulating, NTO films show highly conducting characteristics. The lowest electrical resistivity of 4.80 × 10−3 Ω cm is obtained for ~74 nm thick NTO film. Additionally, relative positions and intensities of the shallow donor level defect states of anatase are analyzed and compared with ZnO to gain fundamental insight into the differences in their electrical behavior. Along with visible region, these films also exhibit high transmittance in NIR range, thereby making these promising transparent conductors in the entire spectral range.

Estimation of Molar Absorption Coefficients of HbA1c in Near UV-Vis-SW NIR Light Spectrum

Diabetes is a serious group of diseases that can cause many complicated problems including sudden mortality. Glycated hemoglobin tests are considered as a reliable tool to diagnose diabetes. To estimate amount of glycated hemoglobin (HbA1c) present in Red Blood Cells (RBCs) optically, the molar absorption coefficient of HbA1c is necessary. We calculate the molar absorption coefficient of HbA1c from percent transmittance spectrum of HbA1c dissolved in water and calibrate the values for a range with molar absorption coefficients of glycated hemoglobin at 535nm Green light and 593nm Yellow light references. We estimate the molar absorption coefficient in the range of 300nm to 1100nm, and we have got a characteristic peak of HbA1c at 411nm (5.20×10<SUP>6</SUP>±1.39 ×10<SUP>6</SUP> M<SUP>-1</SUP>cm<SUP>-1</SUP>) and two more peaks at 540nm (5.63×10<SUP>5</SUP>±1.51×10<SUP>5</SUP> M<SUP>-1</SUP>cm<SUP>-1</SUP>) and 576nm (4.96×10<SUP>5</SUP>±1.33×10<SUP>5</SUP> M<SUP>-1</SUP>cm<SUP>-1</SUP>), respectively. The characteristic and secondary peaks found in our study are verified with previous studies and found consistent with them. The calculated molar absorption coefficient from Near UV to shortwave NIR range can enable the way of non-invasive estimation of HbA1c.

Application of Low-Cost MEMS Spectrometers for Forest Topsoil Properties Prediction.

Increasing temperatures and drought occurrences recently led to soil moisture depletion and increasing tree mortality. In the interest of sustainable forest management, the monitoring of forest soil properties will be of increasing importance in the future. Vis-NIR spectroscopy can be used as fast, non-destructive and cost-efficient method for soil parameter estimations. Microelectromechanical system devices (MEMS) have become available that are suitable for many application fields due to their low cost as well as their small size and weight. We investigated the performance of MEMS spectrometers in the visual and NIR range to estimate forest soil samples total C and N content of Ah and Oh horizons at the lab. The results were compared to a full-range device using PLSR and Cubist regression models at local (2.3 ha, n: Ah = 60, Oh = 50) and regional scale (State of Saxony, Germany, 184,000 km, n: Ah = 186 and Oh = 176). For each sample, spectral reflectance was collected using MEMS spectrometer in the visual (Hamamatsu C12880MA) and NIR (NeoSpetrac SWS62231) range and using a conventional full range device (Veris Spectrophotometer). Both data sets were split into a calibration (70%) and a validation set (30%) to evaluate prediction power. Models were calibrated for Oh and Ah horizon separately for both data sets. Using the regional data, we also used a combination of both horizons. Our results show that MEMS devices are suitable for C and N prediction of forest topsoil on regional scale. On local scale, only models for the Ah horizon yielded sufficient results. We found moderate and good model results using MEMS devices for Ah horizons at local scale ( 0.71, RPIQ 2.41) using Cubist regression. At regional scale, we achieved moderate results for C and N content using data from MEMS devices in Oh ( 0.57, RPIQ ≥ 2.42) and Ah horizon ( 0.54, RPIQ ). When combining Oh and Ah horizons, we achieved good prediction results using the MEMS sensors and Cubist ( 0.85, RPIQ ≥ 4.69). For the regional data, models using data derived by the Hamamatsu device in the visual range only were least precise. Combining visual and NIR data derived from MEMS spectrometers did in most cases improve the prediction accuracy. We directly compared our results to models based on data from a conventional full range device. Our results showed that the combination of both MEMS devices can compete with models based on full range spectrometers. MEMS approaches reached between 68% and 105% of the corresponding full ranges devices values. Local models tended to be more accurate than regional approaches for the Ah horizon. Our results suggest that MEMS spectrometers are suitable for forest soil C and N content estimation. They can contribute to improved monitoring in the future as their small size and weight could make in situ measurements feasible.

Direct Laser Writing for the Formation of Large‐Scale Gold Microbumps Arrays Generating Hybrid Lattice Plasmon Polaritons in Vis–NIR Range (Advanced Optical Materials 12/2021)

Evaldas Stankevicius and co-workers (article number 2100027) demonstrate the formation of large-scale gold microbump arrays generating hybrid lattice plasmon polaritons in the visible to near-infrared range using direct laser writing technique. The demonstrated method shows relevant technological progress in the formation of large-scale metallic gratings by using a cost-effective laser-based technique. It provides new opportunities for hybrid lattice plasmon polariton (HLPP)-based applications in biotechnology, photonics, and plasmonics.

NIR-II Upconversion Photoluminescence of Er3+ Doped LiYF4 and NaY(Gd)F4 Core-Shell Nanoparticles.

The availability of colloidal nano-materials with high efficiency, stability, and non-toxicity in the near infrared-II range is beneficial for biological diagnosis and therapy. Rare earth doped nanoparticles are ideal luminescent agents for bio-applications in the near infrared-II range due to the abundant energy level distribution. Among them, both excitation and emission range of Er3+ ions can be tuned into second biological window range. Herein, we report the synthesis of ∼15 nm LiYF4, NaYF4, and NaGdF4 nanoparticles doped with Er3+ ions and their core-shell structures. The luminescent properties are compared, showing that Er3+ ions with single-doped LiYF4 and NaYF4 nanoparticles generate stronger luminescence than Er3+ ions with doped NaGdF4, despite the difference in relative intensity at different regions. By epitaxial growth an inert homogeneous protective layer, the surface luminescence of the core-shell structure is further enhanced by about 5.1 times, 6.5 times, and 167.7 times for LiYF4, NaYF4, and NaGdF4, respectively. The excellent luminescence in both visible and NIR range of these core-shell nanoparticles makes them potential candidate for bio-applications.

NIR enhanced peroxidase-like activity of Au@CeO2 hybrid nanozyme by plasmon-induced hot electrons and photothermal effect for bacteria killing

The antibacterial application of nanozyme relies on high catalytic efficiency and advanced functions. Plasmon stimulation represents an appealing way to modulate the enzyme-like function, but the utilization efficiency of plasmon excitation remained relatively low. Herein, by selective deposition of a ceria nanozyme on the ends of Au nanorods, we reported a dumbbell-shaped Au@CeO2 hybrid nanozyme with strong surface plasmon resonance (SPR) response in NIR range. This spatially separated structure can simultaneously harvest the plasmon-induced hot carriers and thermal effect, and results in significantly enhanced peroxidase-like activity of Au@CeO2 upon 808 nm irradiation. By using ultrafast transient absorption and in situ irradiation XPS technique, the hot electrons transfer behavior from Au to CeO2 and leading to the change of Ce3+/Ce4+ ratio are disclosed as the main contribution to the activity enhancement. Benefiting from enhanced peroxidase-like activity, Au@CeO2 exhibits efficient broad-spectrum antibacterial activity under NIR irradiation. These results indicate a spatio-temporal way to optimize enzyme-like activity through efficient use of plasmon excitation will be value for improving antibacterial efficacy.

Direct Laser Writing for the Formation of Large‐Scale Gold Microbumps Arrays Generating Hybrid Lattice Plasmon Polaritons in Vis–NIR Range

AbstractSurface plasmon polaritons (SPPs) based light–matter interactions play a major role in photonic sensor applications. In order to implement such sensors in microchip devices or reduce the fabrication costs, a method with high flexibility and large‐scale capabilities must be developed. Here, the formation of large‐scale gold microbumps arrays by using a direct laser writing technique is presented. The fabricated arrays exhibit the hybrid lattice plasmon polaritons in the Vis–NIR range, in the same range as metallic gratings fabricated by lithography‐based techniques. The peak of hybrid lattice plasmon resonance depends on the period of the fabricated arrays, the thickness of the gold film, coupled light polarization, and sample orientation. The experimental results are in good agreement with the theoretical estimation. The demonstrated method shows relevant technological progress in the formation of large‐scale metallic gratings by using a cost‐effective laser‐based technique. It provides new opportunities for hybrid lattice plasmon polariton (HLPP)‐based applications in biotechnology, photonics, plasmonics, and so on.

Near-infrared spectroscopy: Alternative method for assessment of stable carbon isotopes in various soil profiles in Chile

The role of soil in the global carbon cycle and carbon–climate feedback mechanisms has attracted considerable interest in recent decades. Consequently, development of simple, rapid, and inexpensive methods to support the studies on carbon dynamics in soil is of interest. Near-infrared spectroscopy (NIRS) has emerged as a rapid and cost-effective method for measurements of soil properties. The aim of this study was to develop and validate a predictive model for δ13C values using NIRS in various soil profiles across Chile. Eleven sites were selected in the range of 30° to 50° S. These sites represent different soil moisture and soil temperature regimes, clay mineralogies, parent materials, and climates; in addition, they have prairie vegetation and contain C3-type vegetation. Air-dried soil samples were scanned in the NIR range at a resolution of 4 cm−1. The carbon isotopic composition, expressed as δ13C relative to the Vienna Pee Dee Belemnite standard, was analysed using an elemental analyser–isotope ratio mass spectrometer system. A prediction model for δ13C values based on NIRS data was developed through a partial least-squares regression (PLS) model using ten latent variables. A second model was generated using a random forest (RF) approach. The model performances were acceptable. The RF model provided the best results. The values of the root mean square error of prediction for the validation runs for δ13C obtained using the PLS and RF models were 1.38‰, and 1.15‰, respectively. These model performances indicate that NIRS can be used to predict δ13C for the selected dataset. The results of this study support the use of NIRS as a predictive method in soil analyses and as a nondestructive waste-free method for studies on carbon dynamics in soil.

Detection of the organic solvent vapors by the optical gas sensors based on polyaminoarenes

The important problem to ensure the safety of life is the development of effective methods for monitoring of toxic gases in the atmosphere and industrial premises. To ensure such control, various gas sensors are developed that work on the effects of changes in electrical resistance, optical absorption or radiation in a certain spectral range. Most known gas sensors have high operating temperatures, which creates some difficulties in their operation, so more and more attention is paid to sensors based on conjugated electrically conductive polymers, in particular, polyaminoarenes. In result of absorption of inorganic polar gases such as ammonia, nitrogen oxide, hydrogen chloride and others the significant changes in conductivity, optical absorption and morphology of polyaminoarene films are observed. However influence of organic solvent vapors on the optical spectra of polyaminoarene films for today is poorly studied. In the present work the functional polymer films of polyanisidine (PoA) and polytoluidine (PoTI) are proposed as sensitive elements of optical sensors operating at room temperatures. The sensitive films on the transparent SnO2 surface were prepared by electrodeposition. The influence of vapors of organic solvents (dimethylformamide, tetrahydrofuran, chloroform, nitrobenzene, toluene) on the optical characteristics of PoTi and PoA films was established. The optical absorption spectra investigated PoA film was characterized by two band with maximum near 360–410 nm (π–π* transition) and broad band in the range of 620–950 nm which is a superposition of the second and third bands. Influence of organic vapors causes the changes in films coloration. The maximum of sensitivity to the organic vapors for PoTI films in all cases is observed at λ &gt; 550 nm and extends to near-infra-red area indicating a formation of free charge carriers of polaron type. Nonpolar solvent vapors insignificantly affect the optical properties of polyaminoarene films responсes to spectral changes in the visible and NIR range of spectrum. A highest gas sensitivity of optical signal was observed under influence of dimethylformamide and tetrahydrofuran vapors. The time to establish the steady-state value of the optical response is 30–60 s for PoTi, while for PoA reaches 120–180 s depending on the nature of organic vapors.

Luminescence interference-free lifetime nanothermometry pinpoints in vivo temperature

Luminescence nanothermometry makes non-invasive and real-time temperature readings possible in living animals. However, the spectral fluctuation in tissues and fluids, as well as the interaction between fluorophores and environment hinders accuracy of the thermometry. Here, we report a luminescence lifetime-based nanothermometry which specifically addresses this problem. A temporal based calibration (lifetime sensing) in the NIR range, an endogenous thermal response as well as a polymer encapsulation evading environmental factors, altogether help to pinpoint temperature in vivo. Thanks to the highly condensed Nd-Yb ions in a well-protected tiny core-shell nanocrystal (overall 11 nm), a temperature sensitivity about 2.07% K−1 (with 5% Yb3+ doped nanoparticles) and an accuracy of 0.27 K (with 25% Yb3+ doped nanoparticles) in biological fluids are achieved. Hopefully, combining thermally activated energy transfer nanothermometer with anti-interference lifetime thermometry would provide a more accurate temperature measurement for biological and preclinical studies.

Highly Fluorescent Dianionic Polymethines with a 1,3,2-Dioxaborine Core

The difluoroboron β-diketonate ring is ever more used for creating bright polymethine-type fluorophores for the visible and NIR range. Here, we report the synthesis and spectral properties of a series of dianionic cyanine dyes of the rare A1-π-A-π-A1 type, with the central dioxaborine ring (A) embedded into the polymethine chain and various electron-acceptor terminal groups A1. Depending on the nature of the end group, the maxima of their intensive (with molar extinctions up to 380 000 M-1 cm-1) and narrow long-wavelength absorption band lie in the range of 530-770 nm. Their absorption and fluorescence bands are nearly mirror-like and characterized by weak solvatochromism; the marked hypsochromic shifts are observed only when going from polar aprotic solvents to methanol. The designed dianionic dyes have fluorescence quantum yields up to 92 % in the visible range, and even for the NIR dyes, the values of 18-37 % are observed in DMF.

Estimating the Reduced Scattering Coefficient of Turbid Media Using Spatially Offset Raman Spectroscopy.

We propose a new method for estimating the reduced scattering coefficient, μs', of turbid homogeneous samples using Spatially Offset Raman Spectroscopy (SORS). The concept is based around the variation of Raman signal with SORS spatial offset that is strongly μs'-dependent, as such, permitting the determination of μs'. The evaluation is carried out under the assumptions that absorption is negligible at the laser and Raman wavelengths and μs' is approximately the same for those two wavelengths. These conditions are often satisfied for samples analyzed in the NIR region of the spectrum where SORS is traditionally deployed. Through a calibration procedure on a PTFE model sample, it was possible to estimate the μs' coefficient of different turbid samples with an error (RMSEP) below 18%. The knowledge of μs' in the NIR range is highly valuable for facilitating accurate numerical simulations to optimize illumination and collection geometries in SORS, to derive in-depth information about the properties of SORS measurements or in other photon applications, dependent on photon propagation in turbid media with general impact across fields such as biomedical, pharmaceutical, security, forensic, and cultural sciences.

Deposition Time-dependent Study of Structural and Optical Properties of PbS Thin Films Grown by CBD Method

Background: Thin films of PbS were prepared onto glass substrates by using a simple and cost-effective CBD method. Methods: The influence of deposition time on structural, morphology and optical properties have been investigated systematically. The XRD analysis revealed that PbS films are polycrystalline with preferred orientation in (200) direction. Enhancement in crystallinity and PbS crystallite size has been observed with an increase in deposition time. The formation of single-phase PbS thin films has been further confirmed by Raman spectroscopy. The surface morphology analysis revealed the formation of prismatic and pebble-like PbS particles and with an increase in deposition time, these PbS particles are separated from each other without secondary growth. The data obtained from the EDX spectra show the formation of high-quality but slightly sulfur-rich PbS thin films over the entire range of deposition time studied. Results and Conclusion: All films show an increase in absorption with an increase in deposition time and strong absorption in the visible and sub-bandgap regime of the NIR range of the spectrum with red-shift in band edge. The optical band gap shows a decreasing trend, as deposition time increases but it is higher than the bandgap of bulk PbS.

Carboranealkynyl‐Protected Gold Nanoclusters: Size Conversion and UV/Vis–NIR Optical Properties

AbstractStructure evolution has become an effective way to assemble novel monolayer‐protected metal nanomolecules. However, evolution with alkynyl‐stabilized metal clusters still remains rarely explored. Herein, we present a carboranealkynyl‐protected gold nanocluster [Au28(C4B10H11)12(tht)8]3+ (Au28, tht=tetrahydrothiophene) possessing an open‐shell electronic structure with 13 free electrons, which was isolated by a facile self‐reduction method with 9‐HC≡C‐closo‐1,2‐C2B10H11 as the two‐in‐one reducing and protecting agent. Notably, Au28 undergoes a complete transformation in methanol into a stable and smaller‐sized nanocluster [Au23(C4B10H11)9(tht)6]2+ (Au23) bearing 12 valence electrons and crystal‐field‐like split superatomic 1D orbitals. The transformation process was systematically monitored with ESI‐MS and UV/Vis absorption spectra. Au28 and Au23 both display optical absorption covering the UV/Vis–NIR range and NIR emission, which facilitates their potential application in the biomedical and photocatalytic fields.

Copper Oxide Spectral Emission Detection in Chalcopyrite and Copper Concentrate Combustion

In this research, the spectral detection of copper oxide is reported from different combustion tests of chalcopyrite particles and copper concentrates. Combustion experiments were performed in a bench reactor. In all the tests, the radiation emitted from the sulfide particle reactions was captured in the VIS–NIR range. The obtained spectral data were processed by using the airPLS (adaptive iteratively reweighted penalized least squares) algorithm to remove their baseline, and principal component analysis (PCA) and the multivariate curve resolution method alternate least squares (MCR-ALS) methods were applied to identify the emission lines or spectral bands of copper oxides. The extracted spectral pattern is directly correlated with the emission profile reported in the literature, evidencing the potential of using spectral analysis techniques on copper sulfide combustion spectra.