Physics Group

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Revealing Defect Centers in PbWO4 Single Crystals Using Thermally Stimulated Current Measurements
(Journal of Applied Physics, 2024-02-28) Işık, Mehmet; Gasanly, Nizami Mamed
The trap centers have a significant impact on the electronic properties of lead tungstate (PbWO4), suggesting their crucial role in optoelectronic applications. In the present study, we investigated and revealed the presence of shallow trap centers in PbWO4 crystals through the utilization of the thermally stimulated current (TSC) method. TSC experiments were performed in the 10–280 K range by applying a constant heating rate. The TSC spectrum showed the presence of a total of four peaks, two of which were overlapped. As a result of analyzing the TSC spectrum using the curve fit method, the activation energies of revealed centers were found as 0.03, 0.11, 0.16, and 0.35 eV. The trapping centers were associated with hole centers according to the comparison of TSC peak intensities recorded by illuminating the opposite polarity contacts. Our findings not only contribute to the fundamental understanding of the charge transport mechanisms in PbWO4 crystals but also hold great promise for enhancing their optoelectronic device performance. The identification and characterization of these shallow trap centers provide valuable insights for optimizing the design and fabrication of future optoelectronic devices based on PbWO4.
Investigation of Λ (1405)as a molecular pentaquark state
(The European Physical Journal C, 2024-04-30) Azizi, Kazım; Saraç Oymak, Yasemin; Sundu, Hayriye
Λ(1405) is one of the interesting particles with its unclear structure and distinct properties. It has a light mass compared to its non-strange counterpart, despite the strange quark it carries. This situation puts the investigation of this resonance among the hot topics in hadron physics and collects attention to clarify its properties. In this study, we focus on the calculation of the mass and residue of the Λ(1405) resonance within the framework of QCD sum rules. We assign a structure in the form of a molecular pentaquark composed from admixture of K− meson-proton and K¯ 0 meson neutron. Using an interpolating current in this form, the masses and the current coupling constant are attained as m = 1406±128 MeV and λ = (3.35±0.35)×10−5 GeV6 for /q and m = 1402±141 MeV and λ = (4.08 ± 1.08) × 10−5 GeV6 for I Lorentz structures entering the calculations, respectively. The obtained mass values agree well with the experimental data supporting the plausibility of the considered structure.
Reanalysis of rare radiative Ξ− 𝑏→Ξ−⁢𝛾 decay in QCD
(PHYSICAL REVIEW D, 2024-04-30) Aliev, T. M.; Özpineci, A.; Saraç Oymak, Yasemin
The upper limit of the branching ratio of the rare $\Xi_b^-\rightarrow \Xi^- \gamma$ decay is obtained as $BR(\Xi_b^-\rightarrow \Xi^- \gamma)<1.3\times10^{-4}$ by the LHCb. In the present work we study this decay within the light cone QCD sum rules employing the $\Xi_b$ distribution amplitudes. At first stage, the form factors entering the $\Xi_b^-\rightarrow \Xi^- \gamma$ decay are obtained. Next, using the results for the form factors the corresponding branching ratio for this decay is estimated to be $BR(\Xi_b^-\rightarrow \Xi^- \gamma)=(4.8\pm 1.3)\times 10^{-5}$. This value lies below the upper limit established by the LHCb collaboration. Our finding for the branching ratio is also compared with the results of the other theoretical approaches existing in the literature.
Performance Analysis of CuSbSe2Thin-Film Solar Cells with Cd-Free Window Layers
(Materials Letters, 2024-05-15) Sürücü, Gökhan; Bal, Ersin; Gencer, Ayşenur; Parlak, Mehmet; Sürücü, Özge
This study investigates novel thin-film solar cells featuring CuSbSe2 (CASe) with ZnSnO and ZnMgO windows in the layer superstrate structure. For glass/ITO/ZnMgO/CASe/Cu + Au, the J-V measurements reveal a shortcircuit current density (Jsc) of 19.4 mA/cm2, an open-circuit voltage (Voc) of 0.28 Volts, a fill factor (FF) of 39.14 %, and a power conversion efficiency (eta) of 2.13 %. Similarly, glass/ITO/ZnSnO/CASe/Cu + Au exhibits Jsc around 19.6 mA/cm2, Voc around 0.31 Volts, FF around 40 %, and eta of 2.43 %. This paper is a pioneering contribution, introducing novel thin-film solar cells with a distinctive superstrate structure utilizing CASe in conjunction with ZnSnO and ZnMgO windows. The comprehensive study presents the first-ever characterization and performance evaluation of these innovative configurations, shedding light on their unique potential in advancing sustainable solar energy technology.
Revealing photoluminescence and nonlinear optical absorption characteristics of PbMo0.75W0.25O4 single crystal for optical limiting applications
(Physica Scripta, 2024-04-18) Doğan, Anıl; Karatay, Ahmet; Işık, Mehmet; Akhüseyin Yıldız, Elif; Gasanly, Nizami Mamed; Elmalı, Ayhan
Nonlinear absorption properties of PbMo0.75W0.25O4 single crystal fabricated by the Czochralski method were studied. The band gap energy of the crystal was determined as 3.12 eV. Urbach energy which represents the defect states inside the band gap was found to be 0.106 eV. PbMo0.75W0.25O4 single crystal has a broad photoluminescence emission band between 376 and 700 nm, with the highest emission intensity occurring at 486 nm and the lowest intensity peak at 547 nm, depending on the defect states. Femtosecond transient absorption measurements reveal that the lifetime of localized defect states is found to be higher than the 4 ns pulse duration. Open aperture (OA) Z-scan results demonstrate that the PbMo0.75W0.25O4 single crystal exhibits nonlinear absorption (NA) that includes two-photon absorption (TPA) as the dominant mechanism at the 532 nm excitations corresponding to 2.32 eV energy. NA coefficient (βeff) increased from 7.24 × 10−10 m W−1 to 8.81 × 10−10 m W−1 with increasing pump intensity. At higher intensities βeff tends to decrease with intensity increase. This decrease is an indication that saturable absorption (SA) occurred along with the TPA, called saturation of TPA. The lifetime of the defect states was measured by femtosecond transient absorption spectroscopy. Saturable absorption behavior was observed due to the long lifetime of the localized defect states. Closed aperture (CA) Z-scan trace shows the sign of a nonlinear refractive index. The optical limiting threshold of PbMo0.75W0.25O4 single crystal at the lowest intensity was determined as 3.45 mJ/cm2. Results show that the PbMo0.75W0.25O4 single crystal can be a suitable semiconductor material for optical limiting applications in the visible region.
Temperature-dependent tuning of band gap of Fe3O4 nanoparticles for optoelectronic applications
(Chemical Physics Letters, 2024-02-19) Delice, Serdar; Işık, Mehmet; Gasanly, Nizami Mamed
We have investigated structural, morphological and temperature dependent absorption characteristics of Fe3O4 nanoparticles. X-ray diffraction pattern exhibited six diffraction peaks belonging to the cubic phase structure with lattice parameter of a = 8.1602 Å. Spectral variation of absorption coefficient were utilized to achieve Tauc and spectral derivative analyses providing the band gap of the Fe3O4 at varying temperature. The band gap of Fe3O4 nanoparticles was found around 2.08 eV at 300 K and around 2.14 eV at 10 K. The band gap variation with applied temperatures between 10 and 300 K were also investigated using Varshni relation.
Structural and Optical Properties of Interfacial InSe Thin Film
(ACS Omega, 2024-02-09) Emir, Cansu; Tataroğlu, Adem; Coşkun, Emre; Ocak, Sema Bilge
This study presents a comprehensive investigation of the optical and structural characteristics of the indium selenide (InSe) film prepared on a glass substrate. The structural characteristics of the InSe film were analyzed using characterization techniques including X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy while the UV–vis spectrophotometry method was used in the spectral range between 500 and 1000 nm to examine the optical characteristics. Thus, the UV–vis spectroscopic data were used to extract several optical parameters including extinction coefficient (k), optical band gap (Eg), refractive index (n), absorption coefficient (α), and optical conductivity (σopt). The optical transition of InSe was found as a direct transition. However, the optical analysis of this study has revealed that the InSe film has the potential to be used in various optoelectronic and photovoltaic applications.
Nanoremediation of Toxic Dyes Using a Bacterial Consortium Immobilized on Cellulose Acetate Nanofiber Mats
(Polymer Engineering and Science, 2024-01) Erkoç, Esra; Tüzün, İmre; Korkmaz Özkan, Filiz; San Keskin, Nalan Oya; Koçberber Kılıç, Nur
Stenotrophomonas maltophilia and Ochrobactrum sp. demonstrated the highest rates of dye bioremediation. The trials were performed at pH 8, which resulted in the highest bioremediation rate of 64.6% in media containing 21.2 mg L-1 dye. As the dye concentration increased, the pollutant removal decreased, with the maximum bioremoval rate of 70.3%. The removal capacity was increased with an increase in biomass concentration; the highest yield of 91.3% was obtained in media containing 14.2 mg L-1 dye and 12% (v/v) biomass. In nanoremediation studies, the bacterial consortium was immobilized on cellulose acetate nanofiber mats (CA-NFM). Scanning electron microscopic micrographs showed that bead-free nanofiber mats were effective in immobilizing bacterial cells. Moreover, nanofiber structures were capable of supporting exopolysaccharides formation, as confirmed by Fourier transform & imath;nfrared spectroscopy. The bacterial consortium immobilized on CA-NFM showed a maximum bioremoval rate of 56.5%. Reusability tests demonstrated that the consortium immobilized CA-NFM could be used at least five times. Furthermore, after leaving the mat for 1 month at 4 degrees C, it was still usable, and the removal efficiency was found to be 45.4%. Based on our findings, bacteria immobilized on CA-NFM have the potential to be used as highly effective and versatile nanobiotechnological biological sorbents in the treatment of wastewater containing dyes.
Bifunctional Praseodymium-doped SnS2 thin films for photocatalytic and antibacterial applications
(Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2024-04-05) Ech-Chergui, Abdelkader Nebatti; Bennabi, Farid; Işık, Mehmet; Khane, Yasmina; García, Francisco José García; Kadari, Ali Sadek; Guezzoul, M'hamed; Rahman, Ashmalina; Khan, Mohammad Mansoob; Mehdi, Adjdir; Driss-Khodja, Kouider; Amrani, Bouhalouane
This paper introduces a novel application of bifunctional Pr-doped SnS2 thin films, demonstrating their efficacy in both photocatalytic degradation of dye and antibacterial activities. The thin films were fabricated using an eco-friendly spray-coated method, encompassing undoped and Pr-doped SnS2 variations. The study comprehensively examines the structural, morphological, chemical, photocatalytic, and antibacterial characteristics of these films. The crystal structure of both undoped and Pr-doped SnS2 thin films exhibited hexagonal patterns, prominently favouring the growth in (1 0 1) orientation. Notably, an increase in crystallite size was observed with higher levels of Pr-doping. Raman spectroscopy analysis highlighted a distinct peak at 315 cm−1, corresponding to the A1g vibrational mode associated with Sn-S bonds along the c-axis of the structure. Employing X-ray Photoelectron Spectroscopy (XPS), the presence of essential components – Sn, S, and Pr – within the fabricated thin films was confirmed, consistent with experimental values of undoped and Pr-doped SnS2-x compositions. Importantly, the XPS analysis confirmed the integration of the Pr3+ oxidation state within Pr-doped SnS2 films. The photocatalytic degradation and antibacterial activities of the films were investigated. Notably, the photocatalytic potential of the synthesized materials against Congo Red exhibited a direct correlation with the Pr3+ doping percentage, indicating enhanced pollutant degradation with increasing doping levels. Similarly, the antibacterial performance against Escherichia coli displayed improvement with increasing Pr-doping content, highlighting the promising antimicrobial capabilities of the films. This study presents an innovative avenue to address both organic pollutant degradation and microbial control. By harnessing the attributes of Pr-doped SnS2 thin films, this research introduces a promising strategy for sustainable material applications in environmental purification and improvement in public health.
Characterization of Linear and Nonlinear Optical Properties of NaBi(WO4)2 Crystal by Spectroscopic Ellipsometry
(Optical Materials, 2024-02) Işık, Mehmet; Güler, İpek; Gasanly, Nizami Mamed
NaBi(WO4)2 compound has been a material of considerable attention in optoelectronic applications. The present research, in which we examined the linear and nonlinear optical properties of NaBi(WO4)2 crystal using the spectroscopic ellipsometry method, elucidates the optical behavior of the crystal in detail. Our work provides a sensitive approach to determine the spectral characteristic of the crystal. The spectral dependence of various optical parameters such as refractive index, extinction coefficient, dielectric function and absorption coefficient was reported in the range of 1.2-5.0 eV. Optical values such as bandgap energy, critical point energy, single oscillator parameters were obtained as a result of the analyses. In addition to linear optical properties, we also investigated the nonlinear optical behavior of NaBi(WO4)2 and shed new light on the potential applications of the crystal. Absorbance and photoluminescence spectra of the crystal were also reported to characterize optical, electronic and emission behavior of the compound. Our findings may form the basis for a number of technological applications such as optoelectronic devices, frequency conversion, and optical sensors. This research contributes to a better understanding of the optical properties of NaBi(WO4)2 crystal, highlighting the material's role in future optical and electronic technologies.
Growth and optical properties of (Na0.5Bi0.5)(Mo1−xWx)O4 (x = 0.25) single crystal: A potential candidate for optoelectronic devices
(Optical and Quantum Electronics, 2024-01) Güler, İpek; Işık, Mehmet; Gasanly, Nizami Mamed
Double tungstates (DT) and double molybdates (DM) have significant importance because of their optoelectronic applications. Regarding the importance of DT and DM, we investigated experimentally structural and optical properties of (Na0.5Bi0.5)(Mo1−xWx)O4 (x = 0.25) crystal that belongs to the NaBi DT and DM crystals group. Czochralski method was used to grow the single crystals. The structure of the crystal was identified using X-ray diffraction (XRD) measurements. Two sharp peaks associated with tetragonal crystal structure appeared in the pattern. Vibrational modes of the studied crystal were obtained from the Raman experiments. By the help of the Fourier transform infrared spectrophotometer (FTIR) measurements, infrared transmittance spectrum of the studied compound was recorded. Band gap energy wase found around 3.04 eV using two methods, Tauc and derivative analysis, based on transmission spectrum. Based on the analysis of absorption coefficient, Urbach energy was obtained as 0.22 eV. The revealed structural and optical properties of the crystal indicated that the material may be a candidate for optoelectronic devices in which NaBi(MoO4)2 and NaBi(WO4)2 materials are utilized.
A study on the dark and illuminated operation of Al/Si3N4/p‑Si Schottky photodiodes: optoelectronic insights
(Applied Physics A, 2024-01-28) Sürücü, Özge; Yıldız, Dilber Esra; Yıldırım, Murat
This work extensively investigates the operation of an Al/ Si3N4/p-Si Schottky-type photodiode under dark and varying illumination intensities. The photodiode is fabricated by employing the metal–organic chemical vapor deposition (MOCVD) method. A thorough electrical characterization is performed at room temperature, encompassing measurements of cur- rent–voltage (I–V), current–time (I–t), capacitance–time (C–t), and conductance time (G–t). The photodiode’s rectification factor and reverse bias area increased under illumination. The relationship between light power density, barrier height, and diode ideality factor is found. The study also found a strong correlation between light intensity and applied voltage on series resistance (Rs) and shunt resistance (Rsh). Rs values are calculated using Cheung’s functions, revealing the diode’s resistance behavior. The study also examines the photodiode’s photoconductivity and photoconductance, finding a non-linear relation- ship between photocurrent and illumination intensity, suggesting bimolecular recombination. Calculated photosensitivity (K), responsivity (R), and detectivity (D*) values show the device’s light response effectiveness, but efficiency decreases at higher illumination intensities. Transient experiments indicate stable and reproducible photocurrent characteristics, reveal- ing photogenerated charge temporal evolution. This study provides a complete understanding of the Al/Si3N4/p-Si Schottky photodiode’s behavior under different illumination intensities. The findings advance optoelectronic device knowledge and enable their use in advanced technologies.
Nanowire geometry effects on devices and transport mechanisms: SnS2/SiNW heterojunction
(Journal of Materials Science, 2023-10-04) Coskun, Emre; Emir, Cansu; Terlemezoğlu, Makbule; Parlak, Mehmet
The semiconductor nanowire technology has become essential in developing more complex and efficient devices. In this study, the Si nanowire (SiNW) heterojunction structure with a two-dimensional SnS2 thin film was investigated. The SiNW array was created by the metal-assisted etching method because of length control and production over large areas of nanowires. The created SiNW has more diminishing reflectivity compared with Si planar substrate. The diode characteristics of SnS2/SiNW and SnS2/Si planar heterojunctions were investigated by dark current analysis at room temperature, and the improving diode characteristics by the three-dimensional interface between SiNW and SnS2 thin film were discussed. Transport mechanisms of the SiNW heterojunction were also studied for various methods. Thermionic emission and thermally assisted tunneling models are the dominant mechanisms for low voltages (0.02–0.20 V), and the space charge limiting current mechanism dominates the current for comparingly high voltages (0.20–0.40 V). All the values reveal the significant impact of the SiNW on heterojunctions for improving efficiency.
A new method to determine the continuous refractive index of an absorbing film by Generalized Stockwell Transform
(Optics and Laser Technology, 2023-12) Coşkun, Emre; Emir, Cansu; Selamet, Semanur; Parlak, Mehmet; Özder, Serhat
Generalized Stockwell Transform (GST) was adapted to analyze a transmittance signal to continuously determine the refractive index and extinction coefficient. The process is built by analyzing oscillation frequencies of the transmission signal where oscillations exist. The simulation studies clearly show the advantage of the locally referenced phase property of the presented method. The validity of the method was checked for a CdS thin film. The results determined by the GST method are consistent with the results determined by envelope and other signal analyzing methods, and the literature. The noise and relative error analysis of the method was also discussed.
Investigation of a candidate spin-$\frac{1}{2}$ hidden-charm triple strange pentaquark state $P_{csss}$
(Physical Review D, 2023-01-10) Azizi, Kazım; Saraç, Yasemin; Sundu, Hayriye
A candidate triple strange pentaquark state, $P_{csss}$, is investigated through its strong decay channel $P_{csss} \rightarrow \Omega^-J/\psi $. To calculate the relevant strong coupling constants, two possible interpolating currents with spin-parity $J^P=\frac{1}{2}^{-}$ are used. Though the chosen currents for the state under consideration have spin-parity quantum numbers $J^P=\frac{1}{2}^{-}$, they couple to both the positive and negative parity states simultaneously and the corresponding decay widths are obtained for both parities. These widths are obtained as $\Gamma(P_{csss} \rightarrow J/\psi \Omega^-)=201.4\pm 82.5~\mathrm{MeV}$ for the negative and $\Gamma(\widetilde{P}_{csss} \rightarrow J/\psi \Omega^-)=316.4\pm 107.8~\mathrm{MeV}$ for the positive parity state when the first current is used. For the second current, we obtain $\Gamma(P_{csss} \rightarrow J/\psi \Omega^-)=252.5\pm 116.7~\mathrm{MeV}$ for the negative and $\Gamma(\widetilde{P}_{csss} \rightarrow J/\psi \Omega^-)=361.1\pm 98.4~\mathrm{MeV}$ for the positive parity state. These results may provide insights into future experimental observations of such candidate states and help to distinguish and fix their properties.
Investigation of the strange pentaquark candidate P_{\psi s}(4338)^0 recently observed by LHCb
(Physical Review D., 2023-10-01) Azizi, Kazım; Saraç, Yasemin; Sundu, Hayriye
The recently observed strange pentaquark candidate, PΛψs(4338)0, is investigated to provide information about its nature and substructure. To this end, its mass and width through the decay channels PΛψs(4338)0→J/ψΛ and PΛψs(4338)0→ηcΛ are calculated by applying two- and three-point QCD sum rules, respectively. The state is considered as a Ξc¯D meson-baryon molecular structure with spin-parity quantum numbers JP=12−. The obtained mass, mPΛψs(4338)0=4338±130 MeV, and width, ΓPΛψs(4338)0=10.40±1.93 MeV, are consistent with the experimental data within the presented uncertainties. This allows us to assign a Ξc¯D molecular structure of JP=12− for the PΛψs(4338)0 state.
Physical characterization of thermally evaporated Sn–Sb–Se thin films for solar cell applications
(Applied Physics A, 2023-04-26) Bektaş, Tunç; Sürücü, Özge; Terlemezoğlu, Makbule; Parlak, Mehmet
The substitution of Sb in binary SnSe structure may lead to tailoring the physical properties of both SnSe and SbSe, promising absorber layers for thin film solar cells. The resulting Sn-Sb-Se structure could be an outstanding material for photovoltaic applications. In this study, Sn-Sb-Se thin films were deposited by thermal evaporation, and the effect of annealing on the films' structural, optical, and electrical properties were reported. XRD measurement shows that annealing at 300 degrees C yields the best crystalline quality, and structural parameters were calculated using XRD data. SEM and AFM measurements indicate deformation in the film surface after annealing at 400 degrees C. UV-Vis spectroscopy measurement provides a high absorption coefficient which indicates a direct band gap. The band gap and activation energies of the as-grown sample were found as 1.59 eV and 106.1 meV, respectively. The results of SEM, AFM, XRD, Raman, UV-Vis spectroscopy and temperature-dependent photoconductivity measurements were discussed throughout the paper.
Investigation of Tungsten-Based Seleno-Chevrel Compounds with Different Compositions for Efficient Water Splitting
(Advanced Theory and Simulations, 2023-06-29) Dağ, Tuğçe Sevinç; Sürücü, Gökhan; Gencer, Ayşenur; Sürücü, Özge; Özel, Faruk; Çiftçi, Yasemin
This study investigates the photocatalytic water splitting performance for NixW6Se8 (x = 1, 2, 3, 4) Chevrel phases with the chemical formula MxMo6Ch8, where M is a metal and Ch is a chalcogen, with x being 0, 1, 2, 3, or 4. Density Functional Theory (DFT) is used to study the NixW6Se8 (x = 1, 2, 3, 4) Chevrel phases, which includes earth-abundant elements for this specific study as an essential consideration for photocatalytic water splitting. The electronic properties are calculated for the NiW6Se8 and Ni2W6Se8 compounds with thermodynamical, mechanical, and dynamic stabilities. For photocatalytic water splitting, the band gaps below 1.23 eV are excluded, and the conduction and valence band levels are determined to examine the reduction and oxidation potentials for efficient photocatalytic water-splitting materials. An examination of the selected band gaps, along with the conduction and valence band levels, reveals that NiW6Se8 is suitable for both reduction and oxidation reactions; whereas, Ni2W6Se8 is a convenient material only for the reduction reaction. This is the first attempt, as far as the literature reveals, to study Chevrel phases in detail and to identify a suitable compound for photocatalytic water splitting.
DFT Insights into Noble Gold-Based Compound Li5AuP2: Effect of Pressure on Physical Properties
(ACS Omega (American Chemical Society), 2023-04-20) Sürücü, Gökhan; Gencer, Ayşenur; Sürücü, Özge; Ali, Md. Ashraf
In this study, the Li5AuP2 compound is investigated in detail due to the unique chemical properties of gold that are different from other metals. Pressure is applied to the compound from 0 to 25 GPa to reveal its structural, mechanical, electronic, and dynamical properties using density functional theory (DFT). Within this pressure range, the compound is optimized with a tetragonal crystal structure, making it mechanically and dynam-ically stable above 18 GPa and resulting in an increment of bulk, shear, and Young's moduli of Li5AuP2. Pressure application, furthermore, changes the brittle or ductile nature of the compound. The anisotropic elastic and sound wave velocities are visualized in three dimensions. The thermal properties of the Li5AuP2 compound are obtained, including enthalpy, free energy, entropy x T, heat capacity, and Debye temperature. The electronic properties of the Li5AuP2 compound are studied using the Perdew-Burke-Ernzerhof (PBE) and Heyd-Scuseria-Ernzerhof (HSE) functionals. The pressure increment is found to result in higher band gap values. The Mulliken and bond overlap populations are also determined to reveal the chemical nature of this compound. The optical properties, such as dielectric functions, refractive index, and energy loss function of the Li5AuP2 compound, are established in detail. To our knowledge, this is the first attempt to study this compound in such detail, thus, making the results obtained here beneficial for future studies related to the chemistry of gold.
Using urine FTIR spectra to screen autism spectrum disorder
(Scientific Reports, 2023-11-09) Sarıgül, Neslihan; Bozatlı, Leyla; Kurultak, İlhan; Korkmaz Özkan, Filiz
Autism spectrum disorder (ASD) is a heterogeneous neurodevelopmental disorder caused by multiple factors, lacking clear biomarkers. Diagnosing ASD still relies on behavioural and developmental signs and usually requires lengthy observation periods, all of which are demanding for both clinicians and parents. Although many studies have revealed valuable knowledge in this field, no clearly defined, practical, and widely acceptable diagnostic tool exists. In this study, 26 children with ASD (ASD+), aged 3–5 years, and 26 sex and age-matched controls are studied to investigate the diagnostic potential of the Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy. The urine FTIR spectrum results show a downward trend in the 3000–2600/cm region for ASD+ children when compared to the typically developing (TD) children of the same age. The average area of this region is 25% less in ASD+ level 3 children, 29% less in ASD+ level 2 children, and 16% less in ASD+ level 1 children compared to that of the TD children. Principal component analysis was applied to the two groups using the entire spectrum window and five peaks were identified for further analysis. The correlation between the peaks and natural urine components is validated by artificial urine solutions. Less-than-normal levels of uric acid, phosphate groups, and ammonium (NH4) can be listed as probable causes. This study shows that ATR-FTIR can serve as a practical and non-invasive method to screen ASD using the high-frequency region of the urine spectrum.

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