Associated Professor, Spectroscopy department, Physics Division, National Research Centre.
National Research Centre
Nanomaterial, Glasses, Physics, Spectroscopy
A.M. Abdelghany, H.A. El-Batal, F.M. EzzEl-Din, N. ElAlialy, A. Okasha, D. Atta, A.M. Ismail, M. Abdelbaky, M.A. Aboelwafa, and W. Awad Elsevier BV
Aly Okasha, M. S. Gaafar, and Samir Y. Marzouk Springer Science and Business Media LLC
AbstractA spectroscopy study was performed to investigate the absorption and emission behavior of zinc–lead phosphate-doped Sm3+ glasses sample. The parameters, density, ρ, molar volume, Vm, samarium ion concentration N, and mean samarium ion separation, R were calculated. The absorption peaks were assigned and discussed. The band gap and Urbach’s energies analysis were illustrated. The emission spectra and the emission lifetime decay were studied. The CIE diagram coordinate (0.393, 0.601) of the sample’s emission was very close to the TV standard value. The oscillator strength fcal and fexp were calculated using Judd–Ofelt theory, and the model parameter trend was found to be Ω4 > Ω2 > Ω6 which indicates high glasses rigidity. The Absorption and emission cross-sections were studied and illustrated. The obtained optical parameters, absorption, and emission behaviors introduce the samples under investigation as a candidate for orange and reddish-orange photonic applications.
Aly Okasha and A. M. Abdelghany Springer Science and Business Media LLC
Islam E. Kotb, Aly Okasha, Samir Y. Marzouk, and Nehad A. Zidan Elsevier BV
I. S. Mahmoud, M. S. Gaafar, S. Y. Marzouk, A. Okasha, and H. A. Saudi Springer Science and Business Media LLC
H.M. Elsaghier, M.A. Azooz, Nehad A. Zidan, W. Abbas, Aly Okasha, and S.Y. Marzouk Elsevier BV
H.M. Elsaghier, M.A. Azooz, Nehad A. Zidan, W. Abbas, Aly Okasha, and S.Y. Marzouk Elsevier BV
Aly Okasha and S. Y. Marzouk Springer Science and Business Media LLC
The nominal glasses composition ((40-x) % H3BO3—30% CaO—30% Al2O3—x Dy2O3), where x = 1, 2, 3, 4, 5 and 6) were prepared using the melt quenching technique. The absorption spectra reveal the common normal 13 transition peaks of the Dy2O3-doped glasses. The linear and nonlinear optical properties were calculated. The Photoluminescence spectra and the decay lifetime were examined. The Judd–Ofelt parameters trend was Ω4 > Ω2 > Ω6. The oscillator strength of the experimental, and calculated electronic dipole absorption transition were estimated. The radiative life-time, the radiative branching ratio, the emission and absorption transition cross section were also calculated. The gain coefficient of the transitions was predicted. All the calculated parameters were compared with the previous work. The results reveal that the current glasses composition is a good candidate as a lasing host material and the glasses are highly efficient composition when using in the optical communication fibers.
Aly Okasha, S.Y. Marzouk, and A.M. Abdelghany Elsevier BV
Aly Okasha, A.M. Abdelghany, Ahmed R. Wassel, and A.A. Menazea Elsevier BV
Abstract Samples from modified borate Hench's bioglass of nominal composition (45B2O3-24.5Na2O-24.5CaO–6P2O5 wt. %) were successfully synthesized. Both effects of varying gamma irradiation doses (1–10 M rad) and varying dipping times in Simulated Body Fluid (1–4 weeks) were simultaneously studied through different techniques. FTIR resultant spectra of the considered bio-borate glass show bands in the range 410–1600 cm−1 the appearance of small peaks at 1640, 2850 and 2940 cm−1 after irradiation that confirm the existence of the main vibrational units of both triangular and tetrahedral borate groups and minor phosphate groups. XRD for the exposed samples with different doses reveals minor variations in the diffractograms indicating the stability of the constituting component structural units and increase in the hydroxyapatite (HA) hexagonal phase patterns. FTIR spectra after immersion for prolonged times either before and after gamma irradiation show formation of characteristic two far-IR peaks at about 730 and 550 cm−1 together with the formation or increase in the intensity of the peaks at 3445 and 1650 cm−1 due to OH, BOH or POH groups that approve formation of (HA) through the various corrosion steps including hydrolysis, reaction or dissolution of the modifier components and the ultimate interactions to form the calcium phosphate (HA) phase. SEM images confirm the appearance of rounded or nodular-shaped microcrystals especially after extended immersion times. The fraction of four coordinated borons (N4) N4 was observed to increase with immersion time due to the continuous corrosion process including hydration, solubility, besides the fact that the 3-coordinated borons are assumed to be more soluble than compact four-coordinated borons.
Aly Okasha, A.M. Abdelghany, and S.Y. Marzouk Elsevier BV
Abstract Two glasses compositions (50B2O3–30PbO–20SrO–xDy) and (50B2O3–30PbO–20BaO–xDy) where x = 0.0.5%, and 1.0% in wt.% ratio were prepared using melt quenching technique in order to investigate the effect of Ba2+ and Sr2+ ions in Dy3+ ions doped lead borate glass. The optical properties such as bandgap and the refractive index distribution were examined using UV–vis-NIR absorption spectroscopy. The FTIR absorption spectra of all prepared samples were similar except for the metallic bands in the fingerprint region. The obtained experimental data were compared with theoretical data calculated by Judd–Ofelt framework. The Judd–Ofelt parameters Ωλ (λ = 2, 4 and 6) were calculated and the trend was Ω2 ( f e x p ) , the calculated oscillator strength ( f c a l ) , the estimated refractive indexes (n) at each transition, the lifetime of radiative transitions (τ), the branching ratio (β), the absorption cross-section ( σ a b s ( λ ) ) and the emission cross-section ( σ e m i s ( λ ) ) were also estimated and discussed. The optical gain coefficient ( G ( λ ) ) was calculated not only for the most intense emission transition but also other emission peaks. The obtained results indicated that the prepared samples are promising materials for laser emission and optical communication applications.
Aly Okasha, A. M. Abdelghany, S. K. Mohamed, S. Y. Marzouk, H. A. El-Batal, and M. S. Gaafar Springer Science and Business Media LLC
Collective optical, photoluminescence, FTIR spectral studies of increasing Sm2O3 ions (3.2–15 mol%) in strontium phosphate host glass were measured before and after irradiated with (8 Mrad dose) by gamma ray. The undpoed optical spectrum revealed a clear UV absorption peak at 230 nm due to trace iron impurity. Sm2O3-doped glasses exhibit extended visible near IR peaks in two rows, the first extended from 330 to 500 nm with small peaks and the second series extends from 900 to 2500 nm with distinguished peaks. This extended optical-near IR spectral absorption peaks belong to trivalent samarium ions. The photoluminescence (PL) spectra after excitation at 402 nm reveal four PL peaks with the decrease in intensity with increasing samarium content. Upon excitation at 596 nm, 11 peaks are identified and three of which are splitted into component peaks and their intensities decrease with increasing Sm2O3 content. FTIR spectra show distinguished vibrational peaks at the wavenumber range 2000–400 cm−1. Some of the bands are very prominent and obviously revealing some modifications of the phosphate network by the addition of increasing Sm2O3 content.
A. M. Abdelghany, H. A. ElBatal, Aly Okasha, R. M. Ramadan, A. R. Wassel, and A. A. Menazea Springer Science and Business Media LLC
This research focuses on investigating and characterizing the effects of gamma irradiation through successive doses on the bioactivity or bone bonding efficiency of samples from patented Hench’s bioglass upon immersion for extended times in stimulated body fluid (SBF). Combined analytical techniques including FT infrared, X-ray diffraction and scanning electron microscopic measurements were carried out to follow up and identify the changes of the studied properties with both gamma irradiation doses and time of immersion. FTIR spectra before and after both irradiation and immersion processes reveal vibrational bands due to main silicate groups and sharing of some mixed phosphate units in mid wavenumbers. Such collective studies show mainly the growth of the vibrational bands due to water, OH or related groups upon irradiation while the vibrational modes due to the main network forming groups remain unaffected by irradiation. The X-ray diffraction data indicate that gamma irradiation with 10 Mrad causes no changes in the amorphicity of the Hench’s bioglass as before irradiation while diffraction patterns of immersed samples reveal distinct peaks after 4 weeks of immersion. The gamma irradiated sample with 10 Mrad, shows only a peak after 2 weeks and more different peaks after 4 weeks of immersion. SEM micrographs are distinct revealing the appearance and growth of nodular shaped micro-crystallites with prolonged times of immersion confirming the formation of hydroxyapatite.
Samir Y. Marzouk, S. Zobaidi, Aly Okasha, and M.S. Gaafar Elsevier BV
Abstract NdF3-doped borosilicate glasses were prepared using the high-temperature melt components of ingredients of NdF3 doped borosilicate glasses. Optical transmission spectra were collected in the range of 190–2500 nm to determine different optical parameters such as the direct and the indirect optical band gap, Urbach energy, refractive index and optical dielectric constant. The molar refraction, electronic polarizability, and the optical basicity results have been determined using the measured glass refractive indices. Judd-Ofelt calculations were used to predict the oscillator strength of an electronic dipole absorption transition. The order of the parameters Ω2, Ω4 and Ω6 are Ω2
A. Abouelsayed, Badawi Anis, Aly Okasha, Ali M. Ali, W. Elhotaby, and Ahmed S.G. Khalil Elsevier BV
Abstract We present spectroscopy study on cadmium selenide (CdSe) quantum dots (QDs) with different particle sizes linked to multi-walled carbon nanotubes (MWCNTs), so-called (CdSe-QDs/MWCNTs), in the ultraviolet and visible frequency range. Drude-Lorentz (DL) model has been used for fitting the absorption spectra for the samples under investigations. Quantitative information about the different excitonic bands and the particle sizes of CdSe-QDs were obtained from the fitting curves and their components. Furthermore, noncontact terahertz time-domain spectroscopy technique was used to compare the optical properties of the MWCNTs and CdSe-QDs/MWCNTs. Using DL model, the optical conductivities have been estimated from the optical parameters obtained from the data extracted from the differential complex terahertz analysis in the frequency range of 0.06–3 THz. The results illustrate that the optical conductivity of MWCNTs is smaller compared to the CdSe-QDs/MWCNTs due to the increased number of free electrons transferred from CdSe QDs and the availability of mobile carriers.
Ola M. Gomaa, Aly Okasha, Hany M. Hosni, and Amr El-Hag Ali Springer Science and Business Media LLC
Biocompatible polyacrylic acid functionalized CdSe/Cu quantum dot conjugates were synthesized to be used for biomolecules detection. The study results demonstrate the conjugation of the 2.5-3 nm QD with gram negative bacteria with a low detection limit of 28 cfu/ml. The photoluminescence (PL) intensity was correlated to bacterial count, cellular proteins and exopolysaccharides in the tested samples. Confocal Scanning Laser Microscopy (CSLM) images showed significant QD uptake within the cells, both cytoplasm and DNA were the predominant targeted biomolecules, higher fluorescent uptake was shown in gram negative bacteria than that observed for gram positive bacteria. Moreover, PL showed that there was a distinction between live and dead cells as well as gram negative and gram positive cells. Cell viability was not affected even after 6 days (100% viability) rendering it a non-toxic QD. The method is simple and is performed in a single step within approximately 10 min as compared to multi-step protocols for classical microbial count or fluorescent dye staining. All the above results indicate that the CdSe/Cu-PAA QDs are suitable for biomolecule detection, bio-labeling and bioimaging applications.
Aly Okasha, S.Y. Marzouk, Ahmed H. Hammad, and A.M. Abdelghany Elsevier BV
Abstract Glass samples of Fluoroborate glasses of composition 80% B2O3-15%-NaF-5%CaF2 containing different amounts of CoO (0.2, 2, 3%wt) were successfully prepared by melt annealing technique. The samples were characterized using UV-VIS-NIR and FTIR spectrometry. The results showed that the optical properties of the samples are dependent on the Co content within the glass matrix. The optical absorption and transmittance spectra confirmed the incorporation of the CoO in the glass matrix. CoO doped samples showed a blocking region within the visible area which belongs to the tetrahedral Co ions and a transmittance region in the UV. Increasing the CoO content leads to increasing the FWHM of the blocking band and decreasing in the FWHM of the transmittance band. The FTIR spectra showed the characteristics absorption peaks of the triangular and tetrahedral groups in the glass matrix. The existence of CoO leads to resolving and enhancing the bands in the glass samples. The experimental results and the calculated optical parameters for the glass samples recommend them as a promising candidate for band pass filter applications.
Aly Okasha, A. M. Abdelghany, and S. Y. Marzouk Springer Science and Business Media LLC
The glass composition P2O5 60%, SrO 40% (mol%) was prepared then doped with Sm3+ with different mol% (3.2, 6.4, 9.6 and 15%). UV–VIS–NIR spectrometer was used to carry out the absorption spectra of the studied glass samples. The most nominal transitions were assigned among a large number of transitions. Then the radiative properties of the Sm3+ ions were calculated using J–O analysis. The results show a large value of Ω2 than the values Ω4 and Ω6. Another parameter such as the oscillator strength, radiative life time, the transition probabilities, the spectroscopic quality and factors branching ratio of several excited states of the Sm3+ ions was calculated. The laser transition level from 6F9/2→6H5/2, the gain cross-section has been predicted. The emission profile of Sm3+ ions in the present glass shows that the peak of the gain coefficient is shifted toward shorter wavelength as the increase of the inversion. The Optical properties introduce this doped Sm3+ glass as a promising candidate for optical applications.
Ahmed H. Hammad, A. M. Abdelghany, Aly Okasha, and S. Y. Marzouk Springer Science and Business Media LLC
Borate glasses containing sodium fluoride and calcium fluoride were prepared. Nickel oxide was doped into the host glass in different ratios ranging from 0.05 to 1 wt%. Structural studies were exempted by Fourier transform infrared spectroscopy which suggested that the incorporation of fluorine ions in both BO3 and BO4 structural units tends to modify these units to form B–O–F linkage like BOF2 and BOF3, respectively. The glass structure is strongly affected by the ratio of nickel ions especially the infrared absorption region from 400 to 2000 cm−1. Nickel ions are favored to exist in octahedral states occupying the vacancies in the borate network. Optical transition is assumed to be direct transition according to the Yakupanoglu and Arslan procedure with acceptable error ratio about 4.5%. The density values are observed to increase linearly as the nickel ions increases.
Ali Okasha, Diaa Atta, WaelM. Badawy, MarinaV. Frontasyeva, Hanan Elhaes, and Medhat Ibrahim American Scientific Publishers
Aly Okasha, Fathia Gomaa, Hanan Elhaes, Mohamed Morsy, Sherif El-Khodary, Ahmed Fakhry, and Medhat Ibrahim Elsevier BV
Nano titanium dioxide TiO2 was synthesized using hydrolysis method then subjected to several characterizations. XRD revealed that the as-prepared sample is pure anatase phase and after calcinations at 500°C for 3 h the crystallinity has increased. The crystallite size calculated by Debye-Scherrer's formula is 8 nm. The HRTEM image shows an average size of about 9 nm, which is close to the XRD calculation from Scherrer's formula. PM3 semiempirical quantum mechanical calculations were conducted to present the electronic as well as thermal properties for TiO2. FTIR spectra between 800 and 400 cm(-1) are the verification for the lattice vibrations of anatase TiO2. The photo catalytic degradation of methylene blue (MB) was tested by the prepared nano TiO2. Results indicate that, the maximum degradation efficiency reached 94.4% after 120 min of UV irradiation. This increase in the degradation efficiency of TiO2 could be attributed to the reduction in particle size that enhanced the crystallinity as a result of heat treatment.
Diaa Atta and Ali Okasha Elsevier BV
In this article, we discussed some single molecule spectroscopy techniques and methods. We have chosen the simplicity in this survey based on our laboratory experience in this field. We concentrated on the imaging by both techniques the wide field and the scanning microscopes. Other imaging enhancements on the technique like extended resolution wide field, the total internal reflection imaging, and its derivatives are also reviewed. In addition to the imaging techniques, some diffusion techniques also are discussed like fluorescence correlation spectroscopy. The related methods like Forester resonance transfer, photo-induced electron transfer and anisotropy (steady state and time decay) are also discussed. In addition, we elucidated some simple details about the theory behind the FCS and its resulting curve fitting. This review is preceded by general introduction and ended with the conclusion.