Department of Physics

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  • Publication
    Enhancement of the corrosion resistance of mild steel with femtosecond laser- nanostructuring and CrCoNi medium entropy alloy coating
    (Elsevier, 2022) Ahmad, Shahbaz; Ahmad, Waqas; Abu Baker, Aya; Egilmez, Mehmet; Abuzaid, Wael; Orhan, Mehmet Fatih; Ibrahim, Taleb; Khamis, Mustafa; Alnaser, Ali
    In this work, the corrosion resistance of mild steel surface nanostructured with a femtosecond laser and coated with high corrosion resistant CrCoNi (CCN) medium entropy alloy through magnetron sputtering is studied. Substantial improvement in corrosion protection was achieved by applying a combination of high-power femtosecond laser surface nano-structuring at ambient conditions and thin-film coating with (CCN) medium entropy alloy. XRD analysis revealed that femtosecond laser structuring increases the susceptibility of the surfaces to Fe₂O₃ nucleation through oxidation. The surface wettability measurements and electrochemical polarization tests revealed that the combined approach of femtosecond laser structuring and magnetron sputter coating is the best for desired high corrosion resistance. Through this novel method, the resulting corrosion resistance of mild steel was improved by more than one-fold. The results are explained considering the detailed microstructural analysis. The presented findings open new possibilities for corrosion prevention using a combination of new powerful technologies that yield to unprecedented corrosion-inhibition efficacy.
  • Publication
    Insights into rechargeable Zn-air batteries for future advancements in energy storing technology
    (Elsevier, 2023-02-27) Iqbal, Anum; El-Kadri, Oussama; Hamdan, Nasser
    Owing to its high theoretical specific energy density, low cost, abundance and environmental friendliness, the rechargeable Zn-Air batteries (ZAB) are becoming the most prevalent candidate as energy storage devices for consumer electronics, and electric vehicles. Nevertheless, the interaction of O2 as a fuel with the components of ZAB is highly challenging for practical implementations of this technology. The underlying electrochemical reactions in ZAB involving multi-electron transfer, adsorption/evolution of O2, and dissolution of Zn metal in electrolyte, need robust-electrocatalyst and stable Zn/electrolyte interface. This prominently evokes the need for an in-depth study of electrocatalytic reactions occurring at the electrode/electrolyte interphases as well as the physiochemical features of membranes in ZAB. Therefore, this review provides significant insights into the fundamentals of Zn air battery system in terms of the underlying electrochemical mechanism, composition/structural performance relationship of different battery components. A detailed section has been devoted in summarizing the evaluating factors for battery performance including power density, polarization curves, columbic efficiency and correlation of catalyst's redox activity (Eonset, Ehalf-way, and Jd) with the device performance parameters (OCV, Ohmic losses, and Pmax). Moreover, representative studies of in-situ/operando characterizations have also been summarized to reveal the structural stability, reaction kinetics, formation of by-products, and morphological evolution. The intriguing advanced features of ZABs including flexibility, photo-recharge ability, economic feasibility, fast charging, high energy density, improved stability and hybrid Zn battery systems are particularly discussed. For the accomplishment of these functionalities, the chemical heterogeneity and structural modifications of materials (electrode, electrolyte and membranes) with improved electrical conductivity, reduced energy barrier, increased reactive surface area, and improved mass transport behavior at the nanoscale have been anticipated. This material survey could be highly beneficial for the development and modification of new catalysts in the field of electrocatalysis. Additionally, for the prospect of green energy technology, the economic viability and environmental sustainability of ZAB are also highlighted. Lastly, based on the discussion of recent achievements, some challenges and outlooks for maturing the rechargeable Zn air battery technology at the academic level and at the industrial scale are also set forth.
  • Publication
    Renormalization functions of the tricritical O(N)-symmetric Φ⁶ model beyond the next-to-leading order in 1/N
    (IOP Publishing, 2021) Sakhi, Said
    We investigate higher-order corrections to the effective potential of the tricritical O(N)-symmetric Φ⁶ model in 3-2ε dimensions in its phase exhibiting spontaneous breaking of its scale symmetry. The renormalization group β-function and the anomalous dimension γ of this model are computed up to the next-to-next-to-leading order in the 1/N expansion technique and using a dimensional regularization in a minimal subtraction scheme.
  • Publication
    Influence of gas environment on the dynamics of wetting transition of laser-textured stainless steel meshes
    (American Institute of Physics Inc., 2021) Kim, V. V.; Yalishev, V. S.; Khan, S. A.; Iqbal, Muhammad; Boltaev, G. S.; Ganeev, Rashid; Alnaser, Ali
    We analyze the role of surrounding gas and aging in ambient air in the wettability behavior of laser-processed stainless steel meshes. Laser texturing of meshes was carried out in the presence of different gases (N₂, O₂, CO₂, Ar, and SF₆) in ambient atmospheric air and under different vacuum conditions. The influence of each gas on the evolution of the wettability properties after aging in ambient air is analyzed. The effects of low-pressure and vacuum aging allowed transforming the initial superhydrophilic characteristics of the laser-structured meshes to an almost superhydrophobic state.
  • Publication
    Synthesis and low-order optical nonlinearities of colloidal HgSe quantum dots in the visible and near infrared ranges
    (Optical Society of America, 2021) Ganeev, Rashid; Shuklov, Ivan A.; Zvyagin, Andrey I.; Dyomkin, Dmitry V.; Smirnov, Michail S.; Ovchinnikov, Oleg V.; Lizunova, Anna A.; Perepukhov, Alexander M.; Popov, Victor S.; Razumov, Vladimir F.
    We synthesize colloidal HgSe quantum dots and characterize their nonlinear refraction and nonlinear absorption using a Nd:YAG laser and its second harmonic. The 7.5 nm quantum dots were synthesized using the hot-injection method. The nonlinear absorption (β = 9×10ˉ⁷ cm Wˉ¹) and negative nonlinear refraction (γ = -5×10ˉ¹² cm² Wˉ¹) coefficients of colloidal quantum dots were determined using the 10 ns, 532 nm laser radiation. The joint influence of above processes was realized at a higher intensity of probe pulses. In the case of 10 ns, 1064 nm radiation, only negative nonlinear refraction dominated during z-scans of these quantum dots. The studies of optical limiting using two laser sources demonstrated the effectiveness of this process at 532 nm. The role of nonlinear scattering is analyzed. We discuss the mechanisms responsible for the nonlinear refraction processes in colloidal HgSe quantum dots.
  • Publication
    Physicochemical Characterization and Seasonal Variations of PM10 Aerosols in a Harsh Environment
    (Frontiers Media S.A., 2021) Hamdan, Nasser; Alawadhi, Hussain; Shameer, Mohamed
    We have conducted a comprehensive sampling campaign of PM₁₀ pollutants at a site next to a major highway, using standard protocols. Particulate matter (PM) total mass, elemental and chemical/mineral compositions of the fine and coarse fractions of traffic-related PM pollutants were determined using several complementary techniques, including gravimetric analysis, x-ray fluorescence, scanning electron microscopy, energy dispersive spectroscopy, and x-ray diffraction. The PM mass concentrations show that PM₁₀ is within acceptable international standards except during dust storms within the sampled periods. Desert dust, crustal minerals, and sea salts are the major natural sources of PM₁₀ pollution. Examples of these minerals are quartz [SiO₂], calcite [CaCO₃], gypsum [CaSO₄·2H₂O], palygorskite [(Mg,Al)₂Si₄O₁₀ (OH)•₄(H₂O], chlorite-serpentine [(Mg,Fe)₆AlSi₃O₁₀ (OH)₈], halite [NaCl] and nitratine [NaNO₃]. Anthropogenic mineral-based pollutants, such as mascagnite [(NH₄)₂SO₄] and koktaite [(NH₄)₂Ca(SO₄)₂·H₂O], were also observed to contribute to PM₁₀. Trace elements such as Zn, Cu, Fe, Cr and Mn that are markers for traffic sources, Ni and V that are markers for heavy oil combustion, and Pb, which is attributed to industrial emissions, were also identified in PM₁₀. Seasonal variation of the average total mass concentrations and the average mass concentration of elements emitted from natural sources show that the hot season is associated with higher pollution levels compared to the cold season due to increased dust events in the spring and summer. Correlation coefficients between elements have identified elements originating from common sources such as dust storms (e.g., Si, Ca, Al, Fe, Ti, Mn) and sea breeze (Cl and Na), in addition to anthropogenic elements. Enrichment factors calculations have identified elements that mainly have crustal origins, and elements that are partially or highly enriched by humans. Anthropogenic elements were more enriched during the cold season due to reduced human activities in the summer..
  • Publication
    Detailed Chemical Abundances of Star Clusters in the Large Magellanic Cloud
    (American Astronomical Society, 2022) Asa'd, Randa; Hernandez, S.; As’ad, A. M.; Molero, M.; Matteucci, F.; Larsen, S.; Chilingarian, Igor V.
    We derive the first detailed chemical abundances of three star clusters in the Large Magellanic Cloud (LMC), NGC 1831 (436 ± 22 Myr), NGC 1856 (350 ± 18 Myr), and [SL63]268 (1230 ± 62 Myr) using integrated-light spectroscopic observations obtained with the Magellan Echelle spectrograph on Magellan Baade telescope. We derive [Fe/H], [Mg/Fe], [Ti/Fe], [Ca/Fe], [Ni/Fe], [Mn/Fe], [Cr/Fe], and [Na/Fe] for the three clusters. Overall, our results match the LMC abundances obtained in the literature as well as those predicted by detailed chemical evolution models. For clusters NGC 1831 and NGC 1856, the [Mg/Fe] ratios appear to be slightly depleted compared with [Ca/Fe] and [Ti/Fe]. This could be hinting at the well-known Mg–Al abundance anti-correlation observed in several Milky Way globular clusters. We note, however, that higher signal-to-noise observations are needed to confirm such a scenario, particularly for NGC 1831. We also find a slightly enhanced integrated-light [Na/Fe] ratio for cluster [SL63]268 compared with those from the LMC field stars, possibly supporting a scenario of intracluster abundance variations. We stress that detailed abundance analysis of individual stars in these LMC clusters is required to confirm the presence or absence of multiple stellar populations.
  • Publication
    Tests of gluino-driven radiative breaking of the electroweak symmetry at the LHC
    (Institute of Physics, 2022-03-28) Aboubrahim, Amin; Klasen, Michael; Nath, Pran; Syed, Raza
    The recent muon g − 2 result from Fermilab combined with the Brookhaven result, strongly points to new physics beyond the Standard Model which can be well described by the electroweak sector of supersymmetry if the masses of the sleptons and some of the electroweak gauginos are in the few hundred GeV range. However, the Higgs boson mass measurement at 125 GeV indicates a mass scale for squarks which lies in the few TeV region indicating a split mass spectrum between squarks and sleptons. This apparent puzzle is resolved in a natural way in gluino-driven radiative breaking of the electroweak symmetry where radiative breaking is driven by a large gluino mass and the gluino color interactions lead to a large splitting between the squarks and the sleptons. We show that an analysis without prejudice using an artificial neural network also leads to the gluino-driven radiative breaking. We use a set of benchmarks and a deep neural network analysis to test the model for the discovery of light sleptons and sneutrinos at HL-LHC and HE-LHC.
  • Publication
    On the precision of full-spectrum fitting of simple stellar populations. IV. A systematic comparison with results from colour-magnitude diagrams
    (Oxford University Press, 2022-03) Asa'd, Randa; Goudfrooij, Paul; As’ad, A. M.
    In this fourth paper of a series on the precision of ages of stellar populations obtained through the full-spectrum fitting technique, we present a first systematic analysis that compare the age, metallicity and reddening of star clusters obtained from resolved and unresolved data (namely colour-magnitude diagrams (CMDs) and integrated-light spectroscopy) using the same sets of isochrones. We investigate the results obtained with both Padova isochrones and MIST isochrones. We find that there generally is a good agreement between the ages derived from CMDs and integrated spectra. However, for metallicity and reddening, the agreement between results from analyses of CMD and integrated spectra is significantly worse. Our results also show that the ages derived with Padova isochrones match those derived using MIST isochrones, both with the full spectrum fitting technique and the CMD fitting method. However, the metallicity derived using Padova isochrones does not match that derived using MIST isochrones using the CMD method. We examine the ability of the full-spectrum fitting technique in detecting age spreads in clusters that feature the extended Main Sequence Turn Off (eMSTO) phenomenon using two-population fits. We find that 3 out of 5 eMSTO clusters in our sample are best fit with one single age, suggesting that eMSTOs do not necessarily translate to detectable age spreads in integrated-light studies.
  • Publication
    Investigation and Optimization of Mxene functionalized Mesoporous Titania Films as Efficient Photoelectrodes
    (MDPI, 2021) Iqbal, Anum; Hamdan, Nasser
    Three-dimensional mesoporous TiO₂ scaffolds of anatase phase possess inherent eximious optical behavior that is beneficial for photoelectrodes used for solar energy conversion applications. In this regard; substantial efforts have been devoted to maximizing the UV and/or visible light absorption efficiency; and suppressing the annihilation of photogenerated charged species; in pristine mesoporous TiO₂ structures for improved solar illumination conversion efficiency. This study provides fundamental insights into the use of Mxene functionalized mesoporous TiO₂ as a photoelectrode. This novel combination of Mxene functionalized TiO₂ electrodes with and without TiCl₄ treatment was successfully optimized to intensify the process of photon absorption; charge segregation and photocurrent; resulting in superior photoelectrode performance. The photocurrent measurements of the prepared photoelectrodes were significantly enhanced with increased contents of Mxene due to improved absorption efficiency within the visible region; as verified by UV–Vis absorption spectroscopy. The anatase phase of TiO₂ was significantly augmented due to increased contents of Mxene and postdeposition heat treatments; as evidenced by structural analysis. Consequently; an appreciable coverage of well-developed grains on the FTO surface was observed in SEM images. As such; these newly fabricated conductive mesoporous TiO₂ photoelectrodes are potential candidates for photoinduced energy conversion and storage applications.
  • Publication
    Using C++ to Calculate SO(10) Tensor Couplings
    (MDPI, 2021-10-04) Bhagwagar, Azadan; Syed, Raza
    Model building in SO(10), which is the leading grand unification framework, often involves large Higgs representations and their couplings. Explicit calculations of such couplings is a multi-step process that involves laborious calculations that are time consuming and error prone, an issue which only grows as the complexity of the coupling increases. Therefore, there exists an opportunity to leverage the abilities of computer software in order to algorithmically perform these calculations on demand. This paper outlines the details of such software, implemented in C++ using in-built libraries. The software is capable of accepting invariant couplings involving an arbitrary number of SO(10) Higgs tensors, each having up to five indices. The output is then produced in LATEX, so that it is universally readable and sufficiently expressive. Through the use of this software, SO(10) coupling analysis can be performed in a way that minimizes calculation time, eliminates errors, and allows for experimentation with couplings that have not been computed before in the literature. Furthermore, this software can be expanded in the future to account for similar Higgs–Spinor coupling analysis, or extended to include further SO(N) invariant couplings.
  • Publication
    Yukawa coupling unification in an SO(10) model consistent with Fermilab (g − 2) μ result
    (Springer, 2021) Aboubrahim, Amin; Nath, Pran; Syed, Raza
    We investigate the Yukawa coupling unification for the third generation in a class of SO(10) unified models which are consistent with the 4.2 σ deviation from the standard model of the muon g − 2 seen by the Fermilab experiment E989. A recent analysis in supergravity grand unified models shows that such an effect can arise from supersymmetric loops correction. Using a neural network, we further analyze regions of the parameter space where Yukawa coupling unification consistent with the Fermilab result can appear. In the analysis we take into account the contributions to Yukawas from the cubic and the quartic interactions. We test the model at the high luminosity and high energy LHC and estimate the integrated luminosities needed to discover sparticles predicted by the model.
  • Publication
    Corrections to Yukawa couplings from higher dimensional operators in a natural SUSY SO(10) and HL-LHC implications
    (Springer, 2021-01-11) Aboubrahim, Amin; Nath, Pran; Syed, Raza
    We consider a class of unified models based on the gauge group SO(10) which with appropriate choice of Higgs representations generate in a natural way a pair of light Higgs doublets needed to accomplish electroweak symmetry breaking. In this class of models higher dimensional operators of the form matter-matter-Higgs-Higgs in the superpotential after spontaneous breaking of the GUT symmetry generate contributions to Yukawa couplings which are comparable to the ones from cubic interactions. Specifically we consider an SO(10) model with a sector consisting of 126 + 126 + 210 of heavy Higgs which breaks the GUT symmetry down to the standard model gauge group and a sector consisting of 2 × 10 + 120 of light Higgs fields. In this model we compute the corrections from the quartic interactions to the Yukawa couplings for the top and the bottom quarks and for the tau lepton. It is then shown that inclusion of these corrections to the GUT scale Yukawas allows for consistency of the top, bottom and tau masses with experiment for low tan β with a value as low as tan β of 5–10. We compute the sparticle spectrum for a set of benchmarks and find that satisfaction of the relic density is achieved via a compressed spectrum and coannihilation and three sets of coannihilations appear: chargino-neutralino, stop-neutralino and stau-neutralino. We investigate the chargino-neutralino coannihilation in detail for the possibility of observation of the light chargino at the high luminosity LHC (HL-LHC) and at the high energy LHC (HE-LHC) which is a possible future 27 TeV hadron collider. It is shown that all benchmark models but one can be discovered at HL-LHC and all would be discoverable at HE-LHC. The ones discoverable at both machines require a much shorter time scale and a lower integrated luminosity at HE-LHC.
  • Publication
    Investigations of the Co-Pt alloy phase diagram with neutron diffuse scattering, inverse cluster variation method, and Monte Carlo simulations
    (American Physical Society, 2020) Fevre, Mathieu; Sanchez, Juan; Stewart,Ross; Merot, J. S.; Fossard, Frédéric; Le Bouar, Yann; Tanaka, Katsushi; Numakura, Hiroshi; Schmerber, Guy; Pierron-Bohnes, Véronique
    The short-range order in a CoPt alloy was determined at 1203 and 1423 K using neutron diffuse scattering measurements. The effective pair interactions provided by data analysis reproduce well the experimental order-disorder transition temperature in Monte Carlo simulations. They complete previous results reported for the Co-Pt system and are compared to those obtained within tight-binding and ab initio formalisms. Our results show that the important dependence of the nearest-neighbor pair interactions with composition is not related to the sample magnetic state at the measured temperatures. Interactions measured in the paramagnetic domain for the CoPt alloy behave like those in the ferromagnetic domain for the Co₃Pt and Co₀․₆₅Pt₀․₃₅ alloys. The effective pair interactions related to the tight-binding Ising model provide a relatively good description of the CoPt alloy thermodynamics close to the ordering temperature (short-range order and temperature of phase transformation), even if they strongly differ from those measured in this study. The average magnetic moment of Co atoms at high temperatures was determined from the analysis of the intensity contribution that is not dependent on the scattering vector. The obtained value is very close to the moment measured at room temperature or determined from ab initio calculations. This confirms the Curie-Weiss behavior of the CoPt alloy. Finally, transmission electron microscope observations carried out on samples annealed for about 30 days confirmed that the order-disorder transition takes place in the 830–843 K temperature interval at the Co₃Pt composition.
  • Publication
    Application of Quasi-Phase Matching Concept for Enhancement of High-Order Harmonics of Ultrashort Laser Pulses in Plasmas
    (MDPI, 2019) Ganeev, Rashid; Stremoukhov, Sergey; Andreev, A. V.; Alnaser, Ali
    Novel methods of coherent short-wavelength sources generation require thorough analysis for their further amendments and practical implementations. In this work, we report on the quasi-phase matching (QPM) of high-order harmonics generation during the propagation of single and two-color femtosecond pulses through multi-jet plasmas, which allows the enhancement of groups of harmonics in different ranges of extreme ultraviolet. The role of the number of coherent zones; sizes of plasma jets and the distance between them; plasma formation conditions, and the characteristics of the fundamental radiation on the harmonic effciency at quasi-phase matching (QPM) conditions are analyzed. We demonstrate the ~40X enhancement factor of the maximally-enhanced harmonic with respect to the one generated at ordinary conditions in the imperforated plasma.
  • Publication
    B − L violating interactions in supersymmetric SO(10) models
    (IOP Science, 2019) Nath, Pran; Syed, Raza
    An analysis is given of B − L violating interactions in SO(10) arising from the integration of $10+\bar{10}$ of SU(5) of heavy Higgs. The analysis is done within the well defined missing partner model where the doublet-triplet splitting arises naturally. The Higgs representations of the model consist of two 10-plets, one 120, one 210 plet and a $126+\bar{126}$ representations of SO(10). The SO(10) symmetry is spontaneously broken by the singlet in the $126+\bar{126}$ and 210. In this work we focus on the B−L interactions arising from the elimination of $10+\bar{10}$ plets of SU(5). We compute five field and six field B−L violating operators. The analysis extends previous analyses where B−L violating interactions arising from the elimination of $5+\bar{5}$ and $45+\bar{45}$ were computed. Specifically we compute dimension 6, 7 and 9 operators. These interactions can generate GUT scale baryogengesis, proton decay, and 𝓃-\bar{𝓃} oscillations.
  • Publication
    Using the Age and Metallicity of 8 Star Clusters to confirm the Chemical Enrichment History of the LMC
    (IOP Science, 2019) Balaha, Farah; Alhosani, Maryam; Asa'd, Randa; Chillingarian, Igor V.
    In this paper, we find the ages and metallicities of 8 Large Magellanic Cloud (LMC) star clusters obtained from integrated light spectra and use them to obtain the Chemical Enrichment History of the host galaxy. Our results are in good agreement with those obtained from resolved studies. This confirms that this method can be used for far away galaxies for which their star clusters are not resolved.
  • Publication
    Can the Full Spectrum Fitting Technique correctly detect Age Spreads in Young Star Clusters?
    (IOP Science, 2019) Asa'd, Randa; As’ad, A. M.
    Integrated spectra of star clusters have proven to be accurate tools for obtaining age, metallicity and reddening of extragalactic clusters for which resolved data is not available. In this work we investigate the possibility of recovering age spreads of young star clusters (in the range log (age/year) 6.8 to 7.2) using full-spectrum fitting approach and provide the preliminary results using model spectral combinations, in order to examine whether this approach can be used for identifying age-spreads for a grid with combinations of S/N, cluster age and population mass fraction. Our preliminary results show that false age spreads might be obtained when fitting multiple ages using integrated spectra specially for the lower S/N. A more accurate experiment to determine how reliable is the recovery of the input parameters is needed.
  • Publication
    Few-cycle laser driven reaction nanoscopy on aerosolized silica nanoparticles
    (Springer Nature, 2019) Rupp, Philipp; Burger, Christian; Kling, Nora G.; Kübel, Matthias; Mitra, Sambit; Rosenberger, Philipp; Weatherby, Thomas; Saito, Nariyuki; Itatani, Jiro; Alnaser, Ali; Raschke, Markus B.; Rühl, Eckart; Schlander, Annika; Gallei, Markus; Seiffert, Lennart; Fennel, Thomas; Bergues, Boris; Kling, Matthias F.
    Nanoparticles offer unique properties as photocatalysts with large surface areas. Under irradiation with light, the associated near-fields can induce, enhance, and control molecular adsorbate reactions on the nanoscale. So far, however, there is no simple method available to spatially resolve the near-field induced reaction yield on the surface of nanoparticles. Here we close this gap by introducing reaction nanoscopy based on three-dimensional momentum resolved photoionization. The technique is demonstrated for the spatially selective proton generation in few-cycle laser-induced dissociative ionization of ethanol and water on SiO2 nanoparticles, resolving a pronounced variation across the particle surface. The results are modeled and reproduced qualitatively by electrostatic and quasi-classical mean-field Mie Monte-Carlo (M3C) calculations. Reaction nanoscopy is suited for a wide range of isolated nanosystems and can provide spatially resolved ultrafast reaction dynamics on nanoparticles, clusters, and droplets.
  • Publication
    A Simple Model for the Fields of a Chirped Laser Pulse With Application to Electron Laser Acceleration
    (Frontiers in Physics, 2019-12) Salamin, Yousef I.; Carbajo, Sergio
    A simple model is introduced for the fields of a chirped laser pulse. As an application, dynamics of laser-acceleration of a single electron by the fields of a pulse, with a sin4 envelope, is investigated. Multi-GeV energy gains from interaction with pulses of peak intensity I0 ∼ 1020 W/cm2, are reported.