Yazar "Nkungli, Nyiang K." seçeneğine göre listele

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    Excited state dependent fast switching NLO behavior investigation of sp2 hybridized donor crystal as D-?-A push–pull switches
    (Elsevier B.V., 2024) Güleryüz, Cihat; Sumrra, Sajjad H.; Hassan, Abrar U.; Nkungli, Nyiang K.; Muhsan, Muhammad S.; Alshehri, Saad M.
    This research focused on the investigating electronic and optical properties of designed chromophores (TPTP1-TPTP5) to involve their comprehensive analysis, including geometry optimization, UV–Vis spectroscopy, analysis of the transition density matrix (TDM), and exploration of their nonlinear optical (NLO) responses. The chromophore TPTP1 and TPTP2 exhibit significant transitions, making them suitable for optical switching applications. The chromophore TPTP5 stood out with high values for linear polarizability (<α0>, 8.53 × 10-24 esu), first order polarizability β0 (3.86 × 10-24 esu), and second order hyperpolarizability (γ0, 6.41 × 10-24 esu), making it notable for its nonlinear optical response. A positive correlation was observed between their vertical ionization potential (VIP) and the γ0 related NLO response, indicating that higher VIP values correspond to stronger γ0 responses. Their UV–Vis spectroscopy was employed to examine the absorption properties of the chromophores, revealing the wavelengths (λmax) at which they absorbed light and their potential for light harvesting applications. The analysis of the TDM allowed for a deeper understanding of the redistribution of electron density during electronic transitions within the chromophores. This analysis provided valuable insights into the characteristics and nature of their excited states. Additionally, the research investigated the NLO responses of the chromophores, particularly focusing on their third harmonic generation (THG) properties. These NLO properties are crucial for potential applications in optical switches, frequency conversion, and optical signal processing. Overall, the findings from this research contribute to a comprehensive understanding of the electronic and optical properties of the designed chromophores. The obtained results open up new possibilities for their utilization in various technological fields, including light harvesting, photonics, and nonlinear optics.
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    Öğe
    Novel pull–push organic switches with D–?–A structural designs: computational design of star shape organic materials
    (Springer, 2022) Hassan, Abrar U.; Mohyuddin, Ayesha; Güleryüz, Cihat; Nadeem, Sohail; Nkungli, Nyiang K.; Hassan, Sadaf U.; Javed, Mohsin
    The structural alteration with π-linkers was used to design a donor–acceptor type series of 2,2′-(pyrimidine-4,6-diyl)bis(2,3-dihydro-1,3-benzothiazole) (PB)-based chromophores (AH1–AH7) to exploit the adjustments in their optical characteristics. To investigate the electronic geometries, absorption wavelengths, charge transfer processes, and the efect of structural alterations on nonlinear optical (NLO) characteristics, density functional theory (DFT) simulations have been used. During the UV–visible study, several long-range and range separated functionals like B3LYP, CAM-B3LYP, B97XD, and APFD with the 6-311G+(d,p) basis set were used to select the efcient level at DFT. As a response, UV–vis data indicated an intriguing consistency at the B3LYP level across experimental and TD-DFT-based values of PB. All the designed molecules had a smaller energy band gap (0.84–3.67 eV) and wide absorption spectra inside the visible region. Natural bond orbital (NBO) results indicated a signifcant push–pull operation, with donors and π-conjugates exhibiting positive values and most acceptors exhibiting the minimum values. Electronic transformations between electron donors to acceptor moiety, Trifuoromethyl (TFM) via π-conjugated linkers were shown to have a superior linear ˂α>and nonlinear (βtotal) NLO values of 306–474 and 40–230 Debye-Angstrom−1 respectively. When chromophores with one phenyl π-linker were compared to those with the two π-linkers, the chromophores with the higher π-linker showed increased hyperpolarizability. The highest second-order hyperpolarizability (β) was found to be 230.11 DebyeAngstrom−1 which was about fve times higher than urea (standard). This research has shown that by manipulating the kind of π-spacers, novel metal-free NLO compounds may be created, which might be used for high-tech NLO purposes.
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    Theoretical probing of 3D nano metallic clusters as next generation non-linear optical materials
    (Elsevier, 2022) Hassan, Abrar U.; Sumrra, Sajjad H.; Nkungli, Nyiang K.; Güleryüz, Cihat
    The excess electron containing compounds have exceptional initial hyper polarizabilities (σ), making them promising nominees for next generation non-linear optical materials. We investigated the geometric, thermodynamic, electrical, and nonlinear optical aspects of a highly strained, theoretically designed metallic cluster (MC), (Fe3Se2(CO)8, in this paper. The designed MC was thermally stable. Estimated ionization energy was used to characterize electrical stability nature (IE). Moreover, the significantly reduced EH–L values reflected the MC with its outstanding characteristics. The maximum absorption (λmax) for computed absorption of electronic transitions was estimated between 327 nm and 340 nm and HOMO → LUMO transitions were found to be the dominant electronic transition band in the UV–Vis spectral region. When comparing to the excited spectrum, the stimulated spectrum appeared to be substantially blue-shifted, with a wide band between 400 and 700 nm. It had the hyperpolarizability values of up to 4.3 × 104 au, resulting in a significant drop in excited state and higher hyperpolarizability values. Using the traditional two-level model, the resulting first hyperpolarizability was also explained. In this MC, the projections of hyperpolarizability on dipole moment coincided with overall hyperpolarizability, showing unidirectional charge transfer with polarizability at four basis sets (B3LYP, CAM-B3LYP, WB97XD and PBEPBE). The static second hyperpolarizability (β) value of the examined MC was higher. The recent discovery, we feel, can provide inspiration for further research into alternative excess electron first row transition MC for NLO applications.