Infrared Reflectance Spectra Research Articles

Study on Characteristic Spectrum and Multiple Classifier Fusion With Different Particle Size in Marine Sediments

Marine sediments record much information of the ecological process, which highly correlated with global and local environmental change. Particle size and its distributions of sediments indicate different ecological functions, thus are the key questions in marine ecology. The analysis method is tedious and laborious, which is not conducive for in-situ monitoring. Here, a spectral analysis was explored using surface sediments sampled in the intertidal zone of Dongdayang village, Qingdao, China. These samples were dried and sieved to pass through the mesh size of 0.3 mm, 0.2 mm, 0.1 mm, and 0.075 mm, respectively. Then, four types of subsamples were collected with the particle size of 0.3-0.2 mm, 0.2-0.1 mm, 0.1-0.075 mm, and <; 0.075 mm, respectively. The visible and near infrared reflectance spectra (226-975nm) of these subsamples with different particle size were measured. Results showed that there was a negative correlation between the spectral reflectance and the particle size. And the characteristic spectra for particle size classification were 926-975nm. These particle size were classified by the support vector machine algorithm. The classification accuracy for the calibration set and validation set was 100% and 89.06%, respectively. Furthermore, the fusion classifier was compared with the single classifier. Three spectral bands were selected as the single particle size classifier, that is 226-325nm, 826-925nm and 226-975nm. These three single classifiers were fused by voting method, forming multiple classifier fusion. A fusion classifier was recommended whose validation set had the classification accuracy of 93.75%, better than any single classifier. Multiple classifier fusion is a good tool for searching the characteristic spectra of the chemical and physical parameter in sediments. This method provides a solution for the division of particle size in sediment.

Field Manipulation of Infrared Absorption Properties in Thin Films

Infrared (IR) spectroscopy is a sensitive technique for fast and comprehensive analyses of organic and hybrid organic–inorganic materials, surfaces, and thin films. For interpretation of reflection and absorption IR spectra of thin films, vibrational bands in unpolarized IR spectra are often directly inspected. This approach can lead to misinterpretations. Herein, the influence of anisotropy and oscillator strength on the frequency and shape of observed vibrational bands in IR spectra of thin films is investigated. IR ellipsometric, polarization‐dependent reflectance spectra and polarization‐dependent atomic force microscope–IR spectroscopy (AFM–IR) nanopolarimetric absorption measurements of an about 84 nm thick anisotropic polyimide film (PI‐2611) are compared. The s‐ and p‐polarized spectra are used for separation of in‐plane and out‐of‐plane absorption components. The far‐field spectra are interpreted by analytical modeling. In detail, the frequency range of bands related to antiphase and in‐phase C═O stretching vibrations of the imide rings is investigated. For the antiphase C═O vibration as a relatively strong oscillator, the manipulation of absorption by the incident radiation‐induced electric fields in direction normal to the surface can be revealed in p‐polarized reflectance spectra and is identifiable in the p‐polarized IR nanopolarimetric absorption spectra.

Crystal growth, IR specular reflectance and polarized Raman studies of LiNa5Mo9O30 polar single crystal.

A non-centrosymmetric, polar LiNa5Mo9O30 single crystal was grown using Kyropoulos technique and characterized by polarized Raman scattering and polarized infrared specular reflection spectroscopy at room temperature. The comparison to the polycrystalline spectra has been made and assignment of all observed modes to the respective vibrations and their symmetry has been proposed. Based on the four parameter model the infrared reflection spectra were analyzed and the LO-TO splitting has been determined for the observed modes. Stronger anharmonicity of bands assigned to stretching vibrations of the Mo-O⋯Mo bridges has been evidenced. Our results show that this crystal is attractive and promising SRS-active nonlinear optical material for up- and down-Raman laser-frequency converters with the most intense lasing lines at 947 and 884cm-1. Dielectric permittivity studies in the frequency domain exhibit two anomalies that are assigned to thermally activated relaxation and conductivity processes. The observed increase in electrical conductivity above 400K is dominated by ionic contribution and change of the conductivity mechanism.

Structure and microwave dielectric properties of Ba3Nb4-4xTi4+5xO21 ceramics with medium-high permittivity

A series of Ba3Nb4-4xTi4+5xO21 (x = 0.1, 0.2, and 0.3) ceramics with hexagonal structure was synthesized by a solid-state reaction method. The relationships between the composition, crystal structure, and microwave dielectric properties were investigated in terms of ionic polarizability, packing factor, bond valence, octahedral distortion, transmission electron microscopy, Raman spectroscopy and infrared reflectivity spectra. As the x value increases from 0.1 to 0.2, the compounds crystallize in a hexagonal-bronze type (S.G. P63/mcm) structure, whereas the further increase of the x results in Ba6Nb2Ti14O39 appearing as a secondary phase for x = 0.3. The relative density and Q × f firstly increase to a maximum value and then decline, however, the εr and τf values slightly decrease as the x increases. It might be inferred that the excess cation from B-site jump into the C-site strengthening the lattice structure and reducing the dielectric loss and ionic polarizability. The microwave dielectric properties of Ba3Nb3.2Ti5O21 ceramic were obtained after sintering at 1210 °C for 6 h, with permittivity (εr) ∼60.3, quality factor (Q × f) = 9,400 GHz, temperature coefficient of resonant frequency (τf) ∼ 109.7 ppm/°C (10−6/°C). The intrinsic dielectric parameters of Ba3Nb3.2Ti5O21 with εr∼55, Q × f = 19,480 GHz were also obtained by infrared reflectivity spectra.

Linking mineralogy and spectroscopy of highly aqueously alteredCMandCIcarbonaceous chondrites in preparation for primitive asteroid sample return

AbstractThe highly hydrated, petrologic type 1CMandCIcarbonaceous chondrites likely derived from primitive, water‐rich asteroids, two of which are the targets forJAXA's Hayabusa2 andNASA'sOSIRIS‐REx missions. We have collected visible and near‐infrared (VNIR) and mid infrared (MIR) reflectance spectra from well‐characterizedCM1/2,CM1, andCI1 chondrites and identified trends related to their mineralogy and degree of secondary processing. The spectral slope between 0.65 and 1.05 μm decreases with increasing total phyllosilicate abundance and increasing magnetite abundance, both of which are associated with more extensive aqueous alteration. Furthermore, features at ~3 μm shift from centers near 2.80 μm in the intermediately alteredCM1/2 chondrites to near 2.73 μm in the highly alteredCM1 chondrites. The Christiansen features (CF) and the transparency features shift to shorter wavelengths as the phyllosilicate composition of the meteorites becomes more Mg‐rich, which occurs as aqueous alteration proceeds. Spectra also show a feature near 6 μm, which is related to the presence of phyllosilicates, but is not a reliable parameter for estimating the degree of aqueous alteration. The observed trends can be used to estimate the surface mineralogy and the degree of aqueous alteration in remote observations of asteroids. For example, (1) Ceres has a sharp feature near 2.72 μm, which is similar in both position and shape to the same feature in the spectra of the highly alteredCM1MIL05137, suggesting abundant Mg‐rich phyllosilicates on the surface. Notably, bothOSIRIS‐REx and Hayabusa2 have onboard instruments which cover theVNIRandMIRwavelength ranges, so the results presented here will help in corroborating initial results from Bennu and Ryugu.

Structural Characterization, Optical Absorption and Electrical Conduction in Ordered Defect Compound Cu3In5Se9 of the Ternary Cu-In-Se Semiconductor System

The optical absorption coefficient α and electrical conduction as a function of temperature of the semiconductor Cu3In5Se9, an ordered defect compound which crystallizes in a tetragonal structure with space group P$$ \bar{4} $$2c, have been studied. The band gap energy EG varies between 0.994 eV and 0.983 eV in the temperature range between 25 and 300 K. The exponential variation of α with photon energy, observed just below the fundamental absorption edge, confirms the existence in Cu3In5Se9 of the Urbach’s tail. The phonon energy hνp associated with this tail is 101 meV. This is about three times higher than the highest optical phonon mode reported for Cu3In5Se9 from infrared reflectivity spectra. The origin of this high energy is attributed due to the contribution of localized modes produced by structural disorders due to deviation from ideal stoichiometry and donor–acceptor defects pairs. From the analysis of electrical data of n-type Cu3In5Se9 in the temperature range from 80 K to 300 K, it was found that above 100 K the electrical conduction is due to the activation of two shallow donor levels of about 40 meV and 80 meV, probably due to selenium vacancies.

Structure, microwave dielectric performance, and infrared reflectivity spectrum of olivine‐type Mg2Ge0.98O4 ceramic

AbstractAn ultra‐low dielectric loss ceramics Mg2Ge0.98O4 with olivine structure was fabricated by conventional solid‐state route. The phase composition, crystal structure, and microwave dielectric properties were investigated. The phase of Mg2Ge0.98O4 is formed to the orthorhombic forsterite structure with a space group Pmnb (62). The dense microstructure and excellent microwave dielectric properties of Mg2Ge0.98O4 ceramic were obtained at 1360°C for 4 hours, with relative density ~96.4%, εr ~ 7.3, Q × f = 112 400 GHz, and τf ~ −64.6 ppm/°C. The conductive mechanism of Mg2Ge0.98O4 in the low frequency (&lt;1 MHz) was studied by the dielectric spectroscopy and the result with Edc = 0.93 eV demonstrates that the defect was contributed to the double ionized oxygen vacancies. The intrinsic dielectric properties of Mg2Ge0.98O4 in the microwave region were obtained by infrared reflectivity spectra with εr ~ 7.13, Q × f = 120 400 GHz. And, acceptable τf (~+2.6 ppm/°C) of 0.92Mg2Ge0.98O4–0.08CaTiO3 composite ceramic was obtained by adding the CaTiO3.

VIS-NIR wave spectrometric features of acorns (Quercus robur L.) for machine grading

The study is intended for engineers and small-scale forestry owners because it offers a simple solution for acorns quality improvement by machine grading before sowing. Visible diffuse reflectance spectra of single whole acorns (Quercus robur L.), damaged acorns, acorns pericarp, whole and damaged acorn seeds were scanned with spectrometer USB 4000 (Ocean Optics Inc., USA) from 450 to 900 nm at 1 nm intervals. Near infrared reflectance spectra of single acorns material were scanned with spectrometer NirQuest512 (Ocean Optics Inc., USA) from 900 to 2100 nm at 1 nm intervals. English oak acorns cannot be divided from damaged acorns and acorns pericarp in the visible wavelength range. Hard-to-release damaged acorns with shell cracks are eliminated in the NIR-reflectance at a wavelength range from 1400 to 1500 nm or from 1900 to 2000 nm. After the elimination of damaged acorns, good whole acorns can be grading from the acorns rotten seed and acorns pericarp (only one the inner side of a shell) at a wavelength range from 1600 to 1700 nm. The results of this study are limited to these specific samples and cannot be interpreted for acorns of all Quercus species.

Effect of finely-dispersed coal sludges on their floatability

Subject of Research. We study the effect of physical and chemical properties of finely-dispersed coal sludges of “MMK-UGOL” on their floatability. Method. Petrographic analysis of coal was carried out using the analyzer of petrographic properties of SIAMS 620 coal. To identify the presence of the main functional groups in the macromolecule of the organic mass of coal, the method of automated analysis of coal by infrared reflection spectra (IR-spectrum) was used. The electrical conductivity of the pulp with a crushed coal sample was determined by ANION 4100 liquid analyzer. Flotation studies were carried out in laboratory flotation machine of FML-1 type (Research and Production Company “Mechanobr-Technika”, Russia). Main Results. The action mechanism of new reagents in the flotation of finely-dispersed coal sludges has been identified. The flocculating action of “Sinterol” new reagent on the mineral particles of finely-dispersed coal sludges has been elucidated, that improves significantly the selectivity of the flotation process. The optimum flotation mode of thin coal sludges has been developed on the basis of laboratory researches, which increases resource efficiency of coal enrichment technological process due to the decrease in organic weight loss with waste by 33%. Thus, the consumption of the consumed reagents is reduced by 3 times. Practical Relevance. The efficiency of “Sinterol” reagent-flocculant has been confirmed by industrial tests on JSC MMK-COAL (Russia). Thus when applying “Sinterol” reagent- flocculant in the flotation process in an amount of 0.001–0.003 kg/t and simultaneously reducing the total consumption of reagents by an average of 13.0% from 3.000 to 2.613 kg/t, the concentrate yield has increased by 2.5–8.5%, the ash content of the concentrate has decreased by 2.7–3.0%, while the ash content of waste has increased by 2.9–12.3%.

Li5Ti2O6F: a new low-loss oxyfluoride microwave dielectric ceramic for LTCC applications

Use of microwave dielectric ceramics can significantly promote the development of communication devices. The primary criteria for determining their applications are excellent microwave dielectric properties and suitability for co-firing with cheap metals (e.g., Ag, Al). This study first reports the low-temperature synthesis of Li5Ti2O6F with a cubic rock salt structure. Li5Ti2O6F was prepared at 880 °C and had er of 19.6, Q × f of 79500 GHz, and τf of − 29.6 ppm/ °C. The infrared reflectivity spectrum revealed that the dielectric contribution of Li5Ti2O6F in the microwave range was mainly affected by phonon absorption. Experimental study indicated that Li5Ti2O6F had good chemical compatibility versus Ag electrode at 880 °C for 2 h. Given these characteristics, Li5Ti2O6F ceramics exhibited potential for low-temperature co-fired ceramic technology.

Optical properties of RAS (N–CH3-2-NH2-5Cl-Py)(TCNQ)(CH3CN) solvate

The optical, electro-physical and magnetic properties of the radical-anionic salt of the so-called simple composition – (N–CH3-2-NH2-5Cl-Py)(TCNQ) were investigated, (N–CH3-2-NH2-5Cl-Py – N-methyl-2-amine-5-chloro-pyridine). Raman’s scattering spectra and infrared reflection spectra are very similar to quasi-one-dimensional salts based on TCNQ. However, in our case, almost isolated π-dimers (TCNQ)22− are used instead of columns built with TCNQ. Supramolecular contacts involving the amine-cation group combine dimers into infinite chains and thereby reduce the local symmetry of the molecules TCNQ to C2h. These peculiarities of the structure may be the cause of this extraordinary behaviour and the manifestation of vibronic-interaction. The salt is a semiconductor, the temperature dependence of the electrical conductivity is subordinated to the Variable Range Hopping model. According to the ESR data, the salt exhibits weak antiferromagnetic properties.

Fabrication of multifunctional coating with high luminous transmittance, self-cleaning and radiative cooling performances for energy-efficient windows

Due to the huge consumption of energy and shortage of resources, passive cooling is becoming an efficient way for saving energy with a function of reducing energy consumption. This work presents a multifunctional SiO2@TiO2/ZnO laminated coating with high luminous transmittance, self-cleaning capability and radiative cooling performance used for energy-efficient windows. SiO2@TiO2 nanospheres as an upper coating were designed as antireflection layer to achieve high luminous transmittance and degradation layer to achieve self-cleaning. While ZnO nanorods as an undercoat were designed as highly reflective layer to realize radiative cooling and support layer to stabilize upper layer. The bilayer coating exhibits excellent antireflective property for reducing 16% reflectivity in the visible region, thus increasing transmittance up to 73%. TiO2 behaves well on degradation of organic pollutants, as it can completely decompose organic matter within 3 h under UV radiation. This would have a positive impact on the self-cleaning ability of the as-fabricated laminated coating and further beneficial for increasing indoor brightness. Both infrared reflectance spectra and infrared thermal images provide valid evidence of high infrared reflectance and outstanding radiative cooling performance. The reflectivity of the laminated coating is 50.25% higher than that of the blank glass, so the temperature gets 4.5 °C reduction under the same radiation conditions. Therefore, SiO2@TiO2/ZnO laminated coating shows great potential in application of energy-efficient windows and may have an inspiration on developments of smart windows.

Influence of Mn2+ introduction on microwave dielectric properties of CaMgSi2O6 ceramic

In the paper, the phase composition, sintering behavior and microwave dielectric properties of CaMg1-xMnxSi2O6 were investigated via X-ray diffraction, SEM techniques and infrared spectra. Dense ceramic with the lowest porosity was obtained at x = 0.02 when sintered at 1300 °C. Densification had great impacts on the developments of both εr and Q × f. The variation in τf was responsible for [MgO6] octahedron distortion and the existence of a secondary phase. Furthermore, the major contributions to the intrinsic dielectric properties were calculated via infrared reflectivity spectra fitting.

Effects of structural transition on microwave dielectric properties of Sr3(Ti1-xSnx)2O7 ceramics

Sr3(Ti1-xSnx)2O7 (x = 0–1.0) ceramics were prepared via a standard solid-state reaction method. X-ray diffraction patterns and Rietveld refinement results indicated a composition induced onset of octahedral tilting when x > 0.2, and the crystal structure transformed in sequence: tetragonal (I4/mmm) → coexistence of tetragonal and orthorhombic (I4/mmm + Amam) → orthorhombic (Amam). The τf value could be successfully tuned towards zero and the effects of octahedral tilting on the evolution of τf value were emphasized. Meanwhile, the role of tolerance factor in tailoring the resultant τε of the present ceramics was revealed and compared with the empirical rule for complex perovskites. Qf value decreased monotonously with increasing x, which could be elucidated by the variations of extrinsic parameters and intrinsic dielectric loss extrapolated from the infrared reflectivity spectra. The optimum microwave dielectric properties were achieved at x = 0.8 (εr = 18.6, Qf = 45,250 GHz, τf =–14 ppm/oC).

Superhydrophobic copper surface fabricated by one-step immersing method in fatty acid salt aqueous solution for excellent anti-corrosion and oil/water separation properties

One-step immersing method is proposed to fabricate superhydrophobic coating on the surface of copper plate and copper mesh in sodium laurate or sodium decanoate aqueous solution. The appropriate concentration range of fatty acid sodium salts and the immersing time are investigated systematically, exhibiting a short immersing time (3 h) to form superhydrophobic surfaces. The sheet structures on the superhydrophobic surfaces are confirmed by scanning electron microscope and X-ray diffraction measurements. The formation mechanism is analyzed according to the X-ray photoelectron spectroscope and Fourier transform infrared reflectance spectra measurements. Electrochemical impedance spectroscopy measurements indicate the excellent anti-corrosion property with corrosion inhibition efficiency of 99.14% in Yellow Sea water. The superhydrophobic copper mesh is proved to be applicable for a variety of oil/water separation, including oils in lab and in daily life. The superhydrophobic copper surface fabricated in this paper will have potential applications in the protection of metal corrosion and the removal of oil contamination.

Suppression of oxygen vacancies generation in Ba6-3xSm8+2xTi18O54 (x=2/3) microwave dielectric ceramics through Pr substitution

Ba6-3x(PrySm1-y)8+2xTi18O54 (x = 2/3, 0 ≤ y ≤ 0.25, BPST) solid solutions ceramics were fabricated using the traditional solid-state processing. Interestingly, substitution of Pr for Sm not only increased the relative permittivity (εr) and optimized the temperature coefficient of resonant frequency (TCF), but also improved the Q × f value which was unexpected according to the mixing rules. With the increase of y values from 0 to 0.25, the εr gradually increased from 78.1 to 82.9, the Q × f value enhanced from 8300 to 10000 GHz, and the TCF value shifted from −11.5 to +8.8 ppm/°C. The improvements of the Q × f value were strongly dependent on the suppression of Ti3+ and oxygen vacancies generation. The TCF value shifted from negative to positive owing to the decreasing of the tilt angle of TiO6 octahedral, which could be confirmed by Raman spectra. Infrared reflectivity spectrum analysis illustrated that infrared-active modes at low frequencies under 300 cm−1 dominated dielectric polarization in the BPST ceramics. Finally, excellent comprehensive properties (εr = 80.5, Q × f = 9700 GHz, and TCF = −0.9 ppm/°C) were obtained for Ba4(Pr0.15Sm0.85)28/3Ti18O54 ceramic sintered at 1375 °C.

Optical multi-functionalities of Er3+- and Yb3+-sensitized strontium bismuth titanate nanoparticles

Multi-functional up-conversion (UC) phosphors are highly desirable for many potentially technological applications. Here, Er3+- and Yb3+-doped SrBi4Ti4O15 (SBT:xEr3+/yYb3+) UC nanoparticles (NPs) have been successfully synthesized for the first time by a convenient EDTA-citrate approach. The structures and morphologies were characterized by powder X-ray diffraction, Fourier transform infrared reflectivity spectra, scanning electron microscopy, and transmission electron microscopy. Under 980 nm excitation, SBT:xEr3+/yYb3+ UCNPs exhibited bright green and weak red emissions. The UC emission properties were disclosed to be tightly dependent on the Yb3+ and Er3+ concentration and the involved UC mechanism was discussed. More importantly, the noncontact optical thermometric ability were assessed based on the thermo-responsive fluorescence intensity ratio (FIR) technique and the maximum sensitivity (Smax) of SBT:0.15Er3+/0.15Yb3+ UCNPs is about 0.0036 K–1. Excellent repeatability and stability were proven by the thermal-cycling measurements. Furthermore, prominent photo-thermal (PT) effect was obtained with the temperature coefficients (η) being 0.24 and 0.49 °C∙mm2/mW for SBT:0.15Er3+/0Yb3+ and SBT:0.15Er3+/0.15Yb3+ UCNPs, respectively, which showed that the incorporation of Yb3+ was a promising strategy to improve the PT capability. In addition, regularly dynamic response of the PT agent under periodic laser stimulation was also observed. These results imply that SBT:xEr3+/yYb3+ UCNPs could be potentially utilized in thermometers and PT agents.

High performance temperature sensing and optical heating of Tm3+- and Yb3+- codoped SrBi4Ti4O15 up-conversion luminescence nanoparticles

Abstract Up-conversion (UC) phosphors with multiple functions are highly desirable for many potentially technological applications which can stimulate the miniaturization and multipurpose of modern devices. In this work, Tm3+- and Yb3+-codoped SrBi4Ti4O15 (SBT:xTm3+/Yb3+) nanoparticles have been first synthesized by a convenient EDTA-citrate method. The structures and morphologies of SBT:xTm3+/Yb3+ were measured by powder X-ray diffraction, Fourier transform infrared reflectivity spectra and scanning electron microscope. Under 980 nm excitation, SBT:xTm3+/Yb3+ exhibited strong near-infrared (NIR) and weak visible emissions. The UC emissions were unveiled to be tightly related to the Tm3+ concentration and the optimum concentration was determined as x = 0.01. The possible UC mechanism was proposed. Importantly, based on thermo-responsive fluorescence intensity ratio approach, the optical thermometric properties were characterized in the temperature range between 313 and 573 K. The maximum sensitivity of SBT:0.01Er3+/Yb3+ UCNPs was obtained as 7.5 × 10−4 K-1. Besides, excellent repeatability and stability were also realized by the thermal-cycling measurement. Furthermore, prominent photo-thermal (PT) effect was also achieved with a temperature coefficient being 0.81 °C∙mm2/mW. Under periodic laser stimulation, the PT effect of the sample displayed regular response, indicating that the PT effect can be expediently controlled by 980 nm laser. These results indicate that SBT:xTm3+/Yb3+ UCNPs could be potential candidates for temperature sensors and PT agents.

Semiconductor–metal transition in GaAs nanowires under high pressure**Project supported by the National Key R&D Program of China (Grant No. 2018YFA0305900), the National Natural Science Foundation of China (Grant No. 11604116), Beijing Municipal Natural Science Foundation, China (Grant No. 1192017), and Youth Innovation Promotion Association, Chinese Academy of Sciences (Grant No. 2017156).

We investigate the structural phase transitions and electronic properties of GaAs nanowires under high pressure by using synchrotron x-ray diffraction and infrared reflectance spectroscopy methods up to 26.2 GPa at room temperature. The zinc-blende to orthorhombic phase transition was observed at around 20.0 GPa. In the same pressure range, pressure-induced metallization of GaAs nanowires was confirmed by infrared reflectance spectra. The metallization originates from the zinc-blende to orthorhombic phase transition. Decompression results demonstrated that the phase transition from zinc-blende to orthorhombic and the pressure-induced metallization are reversible. Compared to bulk materials, GaAs nanowires show larger bulk modulus and enhanced transition pressure due to the size effects and high surface energy.

High-Throughput Phenotyping of Fire Blight Disease Symptoms Using Sensing Techniques in Apple.

Washington State produces about 70% of total fresh market apples in the United States. One of the primary goals of apple breeding programs is the development of new cultivars resistant to devastating diseases such as fire blight. The overall objective of this study was to investigate high-throughput phenotyping techniques to evaluate fire blight disease symptoms in apple trees. In this regard, normalized stomatal conductance data acquired using a portable photosynthetic system, image data collected using RGB and multispectral cameras, and visible-near infrared spectral reflectance acquired using a hyperspectral sensing system, were independently evaluated to estimate the progression of fire blight infection in young apple trees. Sensors with ranging complexity – from simple RGB to multispectral imaging to hyperspectral system – were evaluated to select the most accurate technique for the assessment of fire blight disease symptoms. The proximal multispectral images and visible-near infrared spectral reflectance data were collected in two field seasons (2016, 2017); while, proximal side-view RGB images and multispectral images using unmanned aerial systems were collected in 2017. The normalized stomatal conductance data was correlated with disease severity rating (r = 0.51, P < 0.05). The features extracted from RGB images (e.g., maximum length of senesced leaves, area of senesced leaves, ratio between senesced and healthy leaf area) and multispectral images (e.g., vegetation indices) also demonstrated potential in evaluation of disease rating (|r| > 0.35, P < 0.05). The average classification accuracy achieved using visible-near infrared spectral reflectance data during the classification of susceptible from symptomless groups ranged between 71 and 93% using partial least square regression and quadratic support vector machine. In addition, fire blight disease ratings were compared with normalized difference spectral indices (NDSIs) that were generated from visible-near infrared reflectance spectra. The selected spectral bands in the range 710–2,340 nm used for computing NDSIs showed consistently higher correlation with disease severity rating than data acquired from RGB and multispectral imaging sensors across multiple seasons. In summary, these specific spectral bands can be used for evaluating fire blight disease severity in apple breeding programs and potentially as early fire blight disease detection tool to assist in production systems.