Milohum Mikesokpo DZAGLI | Université de Lomé (original) (raw)

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Talks by Milohum Mikesokpo DZAGLI

Posters by Milohum Mikesokpo DZAGLI

Characterization of a laser source capable of achieving a high pulsed power density with tunabili... more Characterization of a laser source capable of achieving a high pulsed power density with tunability around 7µm. This source is dedicated to experiment of muonic atoms spectroscopy. Conditions for experiment: pulsed laser source (high power density, tunable wavelength ~6.8 µm and linewidth <0.07 nm). Quantum Cascade Lasers (QCLs) are appropriate laser source for the muonichydrogen experiment: tunable emission wavelength, good precision and high optical power . To shows that QCLs are suitable candidates for the muonic-hydrogen experiment, We performed the tunability of QCLs as function of the temperature and the applied voltage, by measuring at different temperatures and voltages, to look for the moving of the emission wavelength. We give a summary of the measurements performed on QCLs.

Papers by Milohum Mikesokpo DZAGLI

La condition de depot de la couche active est un aspect important dans la fabrication des cellule... more La condition de depot de la couche active est un aspect important dans la fabrication des cellules photovoltaiques organiques. Dans ce papier, nous presentons les resultats de la caracterisation de cellules photovoltaiques obtenues par depot physique en atmosphere ambiante en dehors d’une boite a gant. Nous analysons les parametres electriques extraits de la caracteristique courant-tension de ces cellules obtenues par mesure et traitees dans l’environnement OriginPro8. L’analyse des parametres qui entrent en jeu dans la determination de l’efficacite photovoltaique et l’etude de l’effet de la couche encapsulante d’alumine nous permettent d’entre voir que dans les techniques de fabrication des cellules organiques sur substrat souples a base de PCBM et du P3HT ; un depot a la tournette en atmosphere ambiante est possible. Mots cles : atmosphere ambiante, depot a la tournette, photovoltaique organique. Spin coating of polymer in ambiente atmosphere during fabrication of photovoltaic dev...

Journal of Health and Pollution, 2020

Background. Air pollution has become a major problem around the world and is increasingly an issu... more Background. Air pollution has become a major problem around the world and is increasingly an issue in Togo due to increased vehicular traffic. Gaseous pollutants are released by engines and are very harmful to human health and the environment. The fuels used on the major road in Togo, the N2, are adulterated with unknown contents and are of poor quality. Many of the vehicles come from neighboring countries, such as Benin, Ghana and Nigeria. Objectives. The present study aims to evaluate the pollution rate in Togo through the estimation of the concentrations of sulfur dioxide (SO2), nitrogen oxides (NOx), and particular matter (PM) on the international road, the National Road N2, in Lomé, compared to the World Health Organization's (WHO) standard limit. Methods. The simulations of pollutant concentration were performed using the Industrial Source Complex Short Term Version 3 model, which is included in the United States Environmental Protection Agency Regulatory Model (USEPA) AER...

$Research paper thumbnail of Desorption of Te capping layer from ZnTe (100): Auger spectroscopy, low-energy electron diffraction and scanning tunneling microscopy$

Journal of Fundamental and Applied Sciences, 2016

The influence of the annealing temperature to desorb a protective Te capping layer of the zinc te... more The influence of the annealing temperature to desorb a protective Te capping layer of the zinc telluride (ZnTe (100)) surface was investigated. The surface reconstruction of the ZnTe (100) upon the removal of a Te capping layer grown by the molecular beam epitaxy was characterized by different methods. Auger spectroscopy brought out the chemical composition of the surface before and after annealing; the Low-energy electron diffraction (LEED) gave information about the crystallographic structure. The surface crystallographic configurations of tellurium Te (c (2x2)) and Te (c (2x1)) are confirmed by scanning tunneling microscopy (STM). Such a study reveals a phase transition from a rich-Te to a poor-Te surface as the annealing temperature increases.

The localized surface plasmon resonance (LSPR) is a collective oscillation of nanoparticle conduc... more The localized surface plasmon resonance (LSPR) is a collective oscillation of nanoparticle conduction electrons. LSPR excitations in gold nanoparticles have been used for important sensing and spectroscopy applications. Tuning the optoelectronic properties by controlling coupled surface plasmon SP modes in metals is one of the major challenges in the area of metal nanomaterials. We used a method to fabricate nanochains of gold nanorods, tuning the linear optical properties in a wide wavelength range from visible to the near infrared. We enacted the aggregation behavior by adding L-Cysteine. The linear self-assembly mechanism of gold colloids was studied using the UV–VIS spectroscopy and transmission electron microscopy (TEM). The shift in the longitudinal surface plasmon resonance and the TEM image confirm the bridging between L-Cysteine and gold nanorods, showing their connections end-to-end. Gold nanorods (GNRs) are among the most appealing noble-metal nanoparticles for biomedical...

La théorie électromagnétique de la double Hétérostructure (DH) laser Ga1-xAlxAsySb1-y /Ga1-x’Inx’... more La théorie électromagnétique de la double Hétérostructure (DH) laser Ga1-xAlxAsySb1-y /Ga1-x’Inx’Asy’Sb1-y’/Ga1-xAlxAsySb1-y a été réalisée à partir des équations de MAXWELL. Elle a permis d’établir l’expression du facteur de confinement Г, l’expression du champ électrique à l’intérieur dela diode laser. En particulier, nous montrons qu’une diminution de la composition en Aluminium modifie l’intensité du champ à l’intérieur de DH laser.

Afrique Science: Revue Internationale des Sciences et Technologie, 2010

1-y a été réalisée à partir des équations de Maxwell, Huyghens et Fraunhofer. Elle a permis d'éta... more 1-y a été réalisée à partir des équations de Maxwell, Huyghens et Fraunhofer. Elle a permis d'établir l'expression du champ lointain dans le plan orthogonal à l'hétérojonction. L'optimisation de la structure laser a permis d'établir les conditions pour un meilleur couplage de la DH laser avec la fibre optique. En particulier, nous montrons que le champ perpendiculaire dépend de la différence d'indices ∆n= (n 2-n 1).

Journal of Photochemistry and Photobiology A: Chemistry, 2010

In this work we studied the interaction between CdSe/ZnS core-shell quantum dots (QDs) and bovine... more In this work we studied the interaction between CdSe/ZnS core-shell quantum dots (QDs) and bovine serum albumin (BSA) protein, and the temperature effects on the structural and spectroscopic properties of both, individual QDs and protein and their bioconjugates (QDs@BSA), by fluorescence and UV-vis spectroscopy. The recorded UV-vis data and the calculated rate of BSA fluorescence quenching by the QDs demonstrated that the interaction between them leads to the formation of QDs@BSA complex. Moreover we show that, compared to the monotonically decrease of the non-conjugated QDs fluorescence intensity, the temperature dependence of the QDs@BSA emission has a much more complex behavior, highly sensitive to the conformational changes of the protein.

SPIE Newsroom, 2012

An experiment to study an exotic atom with infrared spectroscopy will measure a fundamental param... more An experiment to study an exotic atom with infrared spectroscopy will measure a fundamental parameter related to the spatial dimensions of a proton.

Natural radionuclides activity concentrations of 226Ra, 228Ra, and 40K in soil and grass samples,... more Natural radionuclides activity concentrations of 226Ra, 228Ra, and 40K in soil and grass samples, statistical analysis of these radionuclides and transfer factors (TFs) from soil to the grass were carried out from phosphate mining and processing sites in southern areas of Togo using gamma-ray spectrometry-based High Purity Germanium (HPGe) detector. The average activity concentrations of 226Ra, 228Ra, and 40K were found within the range usually measured worldwide. Statistical analysis was done by investigating the skewness, the kurtosis, and the density distribution of radionuclides in the study areas. Both skewness and kurtosis displayed that the activity concentrations of soil and grass samples in the dischargement waste site (Kpémé) and mining site (Hahotoé) exhibited slightly positively skewed, negatively skewed, leptokurtic, and platykurtic distributions. The TFs for 226Ra, 228Ra, and 40K from dischargement waste soil to grass were evaluated. The average transfer factors of 226...

Journal of Health and Pollution, 2020

$Research paper thumbnail of Desorption of Te capping layer from ZnTe (100): Auger spectroscopy, low-energy electron diffraction and scanning tunneling microscopy$

Journal of Fundamental and Applied Sciences, 2016

Afrique Science: Revue Internationale des Sciences et Technologie, 2010

Journal of Photochemistry and Photobiology A: Chemistry, 2010

SPIE Newsroom, 2012

Microelectronic Engineering, 2016

Scanning tunneling spectroscopy was used to investigate surface doping in silicon, based on the g... more Scanning tunneling spectroscopy was used to investigate surface doping in silicon, based on the grafting of a boron-containing molecular layer and the subsequent thermal diffusion of boron into silicon. Curve fitting of the experimental I(V) characteristics with a planar computation of the tunnel current yields a dopant concentration that is consistent with secondary ion mass spectrometry analyses in the subsurface region. Additional two-point probe electrical measurements performed at variable tip separations indicate a bulk-like transport, that corresponds to a significant diffusion of the boron impurities below the surface of low doped n-type Si wafers. Such results show the interest of multiple-probe scanning tunneling microscopy as a non-invasive technique to determine the electrically active content of doped layers during the fabrication of advanced integrated circuits. Display Omitted Boron-doping of silicon from molecular monolayer dopingTunneling spectroscopy analysis of the surfaceSurface doping from correlation with numerical simulations

Environmental Earth Sciences

Physical Review Materials, Oct 16, 2018

While non-stoichiometric binary III-V compounds are known to contain group V antisites, the growt... more While non-stoichiometric binary III-V compounds are known to contain group V antisites, the growth of ternary alloys consisting of two group V elements might give additional degrees of freedom in the chemical nature of these antisites. Using cross-sectional scanning tunneling microscopy (STM), we investigate low-temperature grown dilute GaAs1-xPx alloys. High concentrations of negatively charged point defects are found. Combined with transmission electron microscopy and pump-probe transient reflectivity, this study shows that the defects have a behavior similar to the group V antisites. Further analyses with x-ray diffraction point to the preferential incorporation of arsenic antisites, consistent with ab-initio calculations, that yield a formation energy 0.83 eV lower than for phosphorus antisites. Although the negative charge carried by the arsenic antisites in the STM images is shown to be induced by the proximity of the STM tip, the arsenic antisites are not randomly distributed in the alloy, providing insight into the evolution of their charge state during the growth.

Journal of Health and Pollution

Studia Universitatis Babeș-Bolyai Ambientum

Physical Review Materials

Quantum Cascade Lasers (QCLs) represent advanced technology to obtain Mid-Infra Red (MIR) and Far... more Quantum Cascade Lasers (QCLs) represent advanced technology to obtain Mid-Infra Red (MIR) and Far-Infra Red (FIR) laser sources. Experiments were conducted to investigate the optical and electrical characteristics of Alpes SB 1487 QCLs. The laser source achieved pulsed power density on a target cavity with tunability around 7 µm. Measurements of the tunability of the QCLs as function of temperature and the applied voltage were studied to identify the shift in emission wavelength. The results indicated tunability as low as 0.04 nm/V with the pulse voltage and 0.28 nm/K with the sink temperature, respectively at emission wavelength of about 6.8 µm. The characteristics of QCLs confirmed suitability for applications bio-sensing and muonic atom spectro-scopy.

Article, Jan 1, 2016

SPIE Newsroom, 2012