SAJID FAROOQ
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Artigo IPEN-doc 30236 Quantitative analysis of high performance plasmonic metamolecules for targeted deep tissues applications2023 - FAROOQ, SAJID; RATIVA, DIEGO; ARAUJO, RENATO E. deRationally designed gold nanoparticles (Au NPs) show a great potential for biomedical applications. Specifically, for optically induced heating of deep tissues facilitated by plasmonic-assisted lasers, nanostructures with high optical absorption coefficient in biological window are required. Plasmonic metamolecules, such as gold nanodimers (NDs), exhibit a robust localized field enhancement with strong infrared optical absorption. However, an exclusive investigation of the optical/ thermal features of high-performance Au NDs for optical infrared heating remains a challenge. Here, we focus on Au NDs for optothermal characteristics in deep tissues heating procedures. Our analysis encompasses parameters such as absorption cross-sections, field enhancement, and temperature rise with a systematic methodology selecting optimal NDs. Our findings reveal a non-uniform spatial distribution of temperature at the nano-scale and show that short-pulsed laser excitation enhances the temperature near the dimerās junction. Remarkably, when compared to monomeric gold nanorods under the same excitation resonance mode, optically generated heating of Au NDs leads a threefold higher temperature increase. These results evidence valuable insights for using Au NDs as efficient plasmonic nanoheaters in photothermal-assisted applications.Artigo IPEN-doc 29086 Tailoring the scattering response of optical nanocircuits using modular assembly2022 - FAROOQ, SAJID; SHAFIQUE, SHAREEN; AHSAN, ZISHAN; CARDOZO, OLAVO; WALI, FAIZOwing to the localized plasmon resonance of an ensemble of interacting plasmonic nanoparticles (NPs), there has been a tremendous drive to conceptualize complex optical nanocircuits with versatile functionalities. In comparison to modern research, there is still not a sufficient level of sophistication to treat the nanostructures as lumped circuits that can be adjusted into complex systems on the basis of a metatronic touchstone. Here, we present the design, assembly, and characterization of single relatively complex photonic nanocircuits by accurately positioning several metallic and dielectric nanoparticles acting as modular lumped elements. In this research, Au NPs along with silica NPs were used to compare the proficiency and precision of our lumped circuit model analytically. On increasing the size of an individual Au NP, the spectral peak resonance not only modifies but also causes more scattering efficiency which increases the fringe capacitance linearly and decreases the nanoinductance of lumped circuit element. The NPs-based assembly induced the required spectral resonance ascribed by simple circuit methods and are depicted to be actively reconfigurable by tuning the direction or polarization of input signals. Our work demonstrates a vital step toward developing the modern modular designing tools of complex electronic circuits into nanophotonic-related applications.Artigo IPEN-doc 29000 High performance blended nanofluid based on gold nanorods chain for harvesting solar radiation2023 - FAROOQ, SAJID; RATIVA, DIEGO; SAID, ZAFAR; ARAUJO, RENATO E. deColloids composed of metallic nanoparticles are promising working fluids for solar radiation harvesting using Direct Absorption Solar Collectors (DASC), due to a high thermal conductivity characteristic and a broad optical absorption that can be tuned to match the solar spectrum. Recently, different studies report gold nanorod (Au-NR) chains for biosensing and photothermal applications, which have broadband and high absorption cross-section and potential possibilities to orientate the nanoparticle using electromagnetic fields. Moreover, colloids with nanoparticles blended configuration show an efficient solar radiation absorption characteristics. Here, working fluids for DASC based on gold nanorod chains in an unblended and blended configuration are evaluated using numerical simulations. The results indicate that the solar absorption increases proportional to the size of the Au-NR assembly, and the best configuration is obtained for a tetramer structure. By using different blended arrangements such as single Au monomers, dimers, trimmers, and tetramers nanorods, it is possible to obtain solar weighted absorption coefficients close to an ideal solar thermal collector, even obtained at low volume fraction (1Ć10(ā5)). Moreover, the results show an enhancement of the temperature of 58.45 Ā°C for tetramer compared with a monomer structure, both under one sun excitation. Therefore, the Au-NR assembly shows a high potentiality to be explored as a high-performance working fluid for solar thermal collectors.