The High Moulouya Basin (HMB) occupies a key location between the Southern Middle Atlas and the Central High Atlas. Gravity data from the HMB show the presence of three gravity lows. Borehole data show a thin MesoCenozoic cover in the HMB that eliminates the possibility that these lows are due to sedimentary rocks. The gravity anomalies may therefore be related to hidden granitic bodies within the Paleozoic basement. In order to map these granite bodies and associated structures, gravity data sets were processed and enhanced using various mathematical techniques, transformations, and 2D gravity modeling. The following were either better defined or revealed: i) The High Moulouya Batholith is a large NE-SW trending batholith that crops out partially in the Aouli-Mibladen and Boumia Paleozoic inliers. Our study shows the continuity of this batholith with a 90 km long and 30 km wide granitic structure. ii) The Hidden Engil granite is a subcircular, relatively small granite body (20 x 18 km) located at the Middle Atlas's eastern boundary. The hidden granite of Zebzat (30 x 10 km) represents a narrow E-W trending pluton bounded by the High Atlas tectonic structures on its southern boundary. The tectonic influence of these granite bodies may explain, to some extent, the stability of the HMB throughout the development of the Atlasic subsiding basins. The two Atlas basins are separated by the High Moulouya granitecored intrabasinal high. As shown by the horizontal gradient and Euler deconvolution methods, during TriassicLiassic NW-SE extensional events, the formation of the Middle and High Atlas basins was guided by Variscan inherited faults bounding the granitic bodies of the HMB. The main factors responsible for the formation of the High Moulouya granite-cored intrabasinal high are the isostatic compensation that follows the granite emplacement during the Variscan orogeny, the distribution of strain and deformation around the granite bodies during the Triassic-Liassic extensional tectonics and their concomitant buoyancy forces.

The study area corresponds to the Jbel Saghro mountain range located in the Moroccan eastern Anti-Atlas. The area landscape shows a Palaeozoic cover, overlying a Neoproterozoic basement. The Cambrian series present lateral thinning from east to west; this thinning is related to the rifting events occurring during the late Neoproterozoic-Cambrian period. The rifting transformed the Anti-Atlas into horsts and grabens. The grabens recorded important sedimentation through the Lower and Middle Cambrian, while at the horsts, it remained reduced. Four lithological sections were examined: Boumalne, Imiter, Taghazout West, and Taghazout, distributed respectively from west to east. The Lower Cambrian is absent in the Boumalne and Imiter, while the Middle Cambrian series show a thickening from west to east. The rifting was generalised in the Anti-Atlas domain, and produced by NE-SW trending faults. The aim of this work is to identify the deepening of these faults, relying on field and geomagnetic examinations. Several treatments were applied to the Jbel-Saghro residual magnetic field map: reduction-to-pole, horizontal gradient, and Euler's deconvolution. Numerous faults were revealed, including a NE-SW trending system interpreted as Cambrian rifting faults, and a NW-SE trending system described as late Neoproterozoic extension faults. These fault systems are considered responsible for the thickness variations of the Cambrian series along the northern flank of Jbel Saghro.

[fr] Le massif hercynien des Jebilets centrales (Maroc) est caractérisé par l’affleurement de nombreux chapeaux de fer dont certains coiffent des amas sulfurés de grande importance économique (Kettara, Draa Sfar, etc.). Le présent travail porte sur l’interprétation de données magnétiques couvrant l’un de ces chapeaux de fer qui se situe près du village de Laachach à une trentaine de kilomètres au Nord- Ouest de Marrakech. La carte magnétique du secteur étudié met en évidence plusieurs anomalies qui coïncident avec l’affleurement du chapeau de fer. Après réduction au pôle des données, l’analyse détaillée de ces anomalies permet de conclure que celles-ci seraient dues à des structures magnétiques allongées en direction subméridienne et décalées par une série de failles décrochantes dextres. Ces structures présentent généralement un pendage vers l’Ouest mais elles peuvent être localement subver ticales. L’application de la déconvolution d’Euler aux données magnétiques de Laachach permet de cal culer des solutions représentant ces structures dont la profondeur varie de 22 à 254 m. L’interprétation quantitative des deux principales anomalies magnétiques mises en évidence au niveau de la zone d’étude a permis de caractériser la structure profonde des corps magnétiques de Laachach, qui pour raient correspondre à des amas sulfurés, compte tenu du contexte géologique et minier du secteur étu dié. Ainsi, les deux corps modélisés constituent des cibles prioritaires de reconnaissance pour tout pro gramme d’exploration minière susceptible d’être mené sur le site de Laachach.

The aim of the present study is to improve the knowledge of the Haouz basin structure using gravity data analysis. First of all, a residual anomaly map was computed from the Bouguer anomaly, greatly affected by an important regional gravity gradient. The calculated map provides information on the ground density variations mainly attributed to the top of the Paleozoic basement undulations under the sedimentary cover. However, in order to further study this map, it has been later analyzed with a method that allows evidencing different buried geological structures, combining the horizontal gradient and the upward continuations processing. The obtained results allows us to establish a structural map of the Haouz basin which confirms the existence of structures already recognized or assumed by the classic geological studies, and highlights accidents, as yet, unknown until the present time. This map shows that the fault system of the Haouz basin is organized in two families of directions NE-SW and NW-SE.

CuIn1−xGaxSe2 thin films were prepared by one step electrodeposition from reagents CuSO4, In2(SO4)3, SeO2 and Ga2(SO4)3. The influence of deposition parameters (electrolyte composition, concentration of reagent and deposition potential) on film composition was studied. The structure, composition, morphology, optical and electrical properties of as-deposited and of annealed films were investigated. The X-ray diffraction analysis showed that the films annealed above 350 °C have a chalcopyrite structure of CuInSe2. The concentration of In2(SO4)3 affects the composition of In and Se in the films. The optical band gap of the films was varied between 1.01 and 1.26 eV by increasing the Ga content in the films. The electrical resistivity of CIS at room temperature decreased down to 10 Ω cm. The conduction mechanism in the CIS films was investigated in the temperature range 150 to 350 K.

CuIn1-xGaxSe2 thin films were deposited onto Mo and SnO2 coated glass substrates at potentials in the interval -350 to -600 mV by one step electro-deposition from reagents CuSO4, In-2(SO4)(3), SeO2 and Ga-2(SO4)(3). The influence of Ga-2(SO4)(3) concentration on the compositions of the films was studied. The crystalline structure, composition, morphology, opto-electronic properties of the as-deposited and annealed films was investigated. The films annealed under vacuum at 400 degrees C are polycristallins and show preferred orientation (112) as confirmed by X-ray diffraction analysis. Optical absorption studies of these films indicated that the band gap value for x = 0.32 is of about 1.25 eV.

CuInSe 2 thin films were prepared by one step electrodeposition from reagents CuSO 4 , In 2 (SO 4 ) 3 , SeO 2 and using citric acid as complexing agent. The influence of deposition parameters (electrolyte composition, concentration of reagent and deposition potential) on film composition was studied. The structure, composition, morphology and opto-electric properties of as deposited and of annealed films were investigated. The stoichiometric CulnSe 2 were obtained at concentration of reagent: 3, 3 and 5mM respectively at potentials varying between -500 and -700 mV. The formation of chalcopyrite phase of CulnSe 2 was confirmed by X-ray diffraction for samples annealed at temperature above 350°C. The concentration of In 2 (SO 4 ) 3 affects the composition of In and Se in the films. Optical absorption studies indicate band gap values between 1.01 and 1.10 eV. The electrical resistivity of the films at room temperature is in the order of 10 Ωcm.

CuIn 1-x Ga x Se 2 thin films were deposited onto Mo and SnO 2 coated glass substrates at potentials in the interval -350 to -600 mV by one step electro-deposition from reagents CuSO 4 , In 2 (SO 4 ) 3 , SeO 2 and Ga 2 (SO 4 ) 3 . The influence of Ga 2 (SO 4 ) 3 concentration on the compositions of the films was studied. The crystalline structure, composition, morphology, opto-electronic properties of the as-deposited and annealed films was investigated. The films annealed under vacuum at 400°C are polycristallins and show preferred orientation (112) as confirmed by X-ray diffraction analysis. Optical absorption studies of these films indicated that the band gap value for x = 0.32 is of about 1.25 eV.

CuInSe 2 thin films were prepared by one step electrodeposition from reagents CuSO 4 , In 2 (SO 4 ) 3 , SeO 2 and using citric acid as complexing agent. The influence of deposition parameters (electrolyte composition, concentration of reagent and deposition potential) on film composition was studied. The structure, composition, morphology and opto-electric properties of as deposited and of annealed films were investigated. The stoichiometric CulnSe 2 were obtained at concentration of reagent: 3, 3 and 5mM respectively at potentials varying between -500 and -700 mV. The formation of chalcopyrite phase of CulnSe 2 was confirmed by X-ray diffraction for samples annealed at temperature above 350°C. The concentration of In 2 (SO 4 ) 3 affects the composition of In and Se in the films. Optical absorption studies indicate band gap values between 1.01 and 1.10 eV. The electrical resistivity of the films at room temperature is in the order of 10 Ωcm.

CuInSe2 thin films were prepared by one step electrodeposition from reagents CuSO4, In-2(SO4)(3), SeO2 and using citric acid as complexing agent. The influence of deposition parameters (electrolyte composition, concentration of reagent and deposition potential) on film composition was studied. The structure, composition, morphology and opto-electric properties of as deposited and of annealed films were investigated. The stoichiometric CuInSe2 were obtained at concentration of reagent: 3, 3 and 5mM respectively at potentials varying between -500 and -700 mV. The formation of chalcopyrite phase of CuInSe2 was confirmed by X-ray diffraction for samples annealed at temperature above 350 degrees C. The concentration of In-2(SO4)(3) affects the composition of In and Se in the films. Optical absorption studies indicate band gap values between 1.01 and 1. 10 eV. The electrical resistivity of the films at room temperature is in the order of 10 Omega cm.

Epitaxial layers of ZnSe and ZnS have been grown on GaAs (100) substrates by low-pressure metal-organic vapor phase epitaxy (MOVPE) and etched out from their substrates, The optical qualify of the layers has been investigated at 2 K by low-intensity reflection, transmission and photoluminescence measurements.At high excitation intensities, the near-band-edge luminescence has been determined in both ZnS and ZnSe samples. Exciton and biexciton contributions have been studied. (C) 1997 Elsevier Science S.A.

The variable stripe length method is used to study optical gain in MOVPE-grown ZnSGaAs epitaxial layers. Optical gain and spontaneous emission spectra are extracted from experimental results. A net optical gain of about 30 cm−1 under excitation by a XeCl laser having a power density of 100 kW cm−2 is observed at very low temperatures (T < 20 K) and it is rapidly quenched for higher temperatures. Gain is interpreted to be due to stimulated emission from the bound exciton state and from the biexciton ground state towards free exciton levels. The spectral shape of the gain spectrum is well fitted by the sum of these two contributions. Smaller gain at lower photon energies is obtained due to exciton-excition collisions.

The detailed characterization of metal organic vapour phase epitaxy grown ZnS layers on GaAs is the first step towards the study of their different non-linear optical properties performed with nanosecond lasers. Biexciton phenomena (with a binding energy of about 10 meV) are observed in photoluminescence-excitation and optical-gain spectra.

High quality MOVPE-grown ZnS/GaAs epilayers are characterized by reflection, transmission and linear photoluminescence (PL) spectroscopy at 2 K. The GaAs substrate of a part of each ZnS layer is removed and the optical properties of as-grown and etched surfaces are compared. The splitting (caused by the thermally induced strain) of the topmost Gamma(8) valence band into the heavy and light-hole subbands (Delta(hl)=4 meV) and the transitions involving exciton ground and excited states are better seen in PL excitation spectra than in ordinary PL spectra. From the analysis of the nonlinear PL and PL excitation spectra, we can conclude the existence of biexcitons with a binding energy of about 10 to 12 meV under an intermediate intensity of excitation (a density of about 2.5x10(16) to 2.5x10(17) e-h excited pairs per cm(3)).

We present a thorough investigation of the different relaxation channels opened in a strongly interacting system of excitonic quasiparticles in CuCl for density regimes ranging up to 50 MW/cm2. A spectrally narrow pump beam consisting of 30-ps pulses is tuned around one-half the biexciton energy. It creates an initial distribution of biexcitons through resonant two-photon absorption. A spectrally broad probe beam made of pulses that also have 30-ps duration monitors the excitation-induced variation of the transmission spectrum of CuCl samples near the Z3 exciton resonance. Coherent processes corresponding to parametric emissions of various orders are observed. Absorption and gain bands that reflect the evolution of biexciton and exciton populations on their respective dispersion curves are followed as functions of the time delay between pump and probe pulses.

By measuring the dynamical shift of interference fringes in epitaxial layers of CuCl, using picosecond “pump and test” experiments, the temporal evolution of the nonlinear refractive index of this compound at low temperatures is obtained. This time behaviour analysed at different photon energies of the test beam is shown to depend on the intensity and photon energy of the pump beam. This observed index change is closely related to the dynamics of the polaritons created by the pump beam.

The dynamics of polaritons created from resonantly excited biexcitons is studied in Cucl. A broadening of the exciton absorption is induced by a polariton phase-space filling effect.

It is shown that a dynamical (i.e., frequency-dependent) collision broadening is necessary to explain the observed spectra of induced absorption in CuCl, which exhibit remarkable exponential absorption wings. The calculated analytical collision broadening allows us to determine the time development of the distribution of optically generated excitonic quasiparticles from transmission spectra, measured in time-resolved pump-and-probe experiments.

The time evolution of the complex dielectric function of CuCl is studied under high excitation conditions at 4 K, through a “pump and probe” method with a 30 ps time resolution.