Synthesis and room temperature magnetic and magneto-optical characterization of size-controlled nickel nanoferrite based ferrofluids

2004 ◽  
pp. 109-112
Author(s):  
M. H. Sousa ◽  
F. A. Tourinho ◽  
J. Depeyrot ◽  
E. Dubois ◽  
R. Perzynski
Keyword(s):  
Room Temperature ◽  
Optical Characterization ◽  
Size Controlled

Thermo-Optical Properties of Perfluorinated Sulfonic Acid Membranes: An Investigation of Hydration Based on Absorption Spectra

2017 ◽  
Vol 71 (11) ◽  
pp. 2504-2511 ◽  
Author(s):  
Daniele T. Dias ◽  
Guy Lopes ◽  
Tales Ferreira ◽  
Ivanir L. Oliveira ◽  
Caroline D. Rosa
Keyword(s):  
Sulfonic Acid ◽  
Room Temperature ◽  
Water Retention ◽  
Structural Changes ◽  
Optical Characterization ◽  
Scanning Calorimetry ◽  
Experimental Procedure ◽  
Nafion Membranes ◽  
Perfluorinated Sulfonic Acid

The Nafion membranes are widely used in electrochemical applications such as fuel cells, chlor-alkali cells, and actuators–sensors. In this work, the thermal-optical characterization of Nafion in acid form was performed by photoacoustic spectroscopy, thermogravimetry, and differential scanning calorimetry. In the experimental procedure three distinct hydration levels were considered: (1) pristine membrane (λ ≅ H2O/–SO3H ≅ 5.6); (2) swelling process (λ ≅ 17.4); and (3) drying at controlled room temperature after swelling process (λ ≅ 6.5). The discovered behaviors showed significant irreversible structural changes induced by water retention in the membrane. These structural changes depend on the water population present in the clusters and also affect the directional thermal diffusivity of the membrane irreversibly.

L-cysteine functionalized graphene quantum dots for sub-ppb detection of As (III)

2021 ◽  
Author(s):  
Md. Farhan Naseh ◽  
Neelam Singh ◽  
Jamilur R. Ansari ◽  
Ashavani Kumar ◽  
Tapan Sarkar ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Quantum Dots ◽  
Room Temperature ◽  
Graphene Quantum Dots ◽  
Optical Characterization ◽  
Functionalized Graphene ◽  
Transmission Electron ◽  
Sensitivity And Selectivity ◽  
Structural Characterizations

Abstract Here, we report functionalized graphene quantum dots (GQDs) for the optical detection of arsenic at room temperature. GQDs with the fluorescence of three fundamental colors (red, green, and blue) were synthesized and functionally capped with L-cysteine (L-cys) to impart selectively towards As (III) by exploiting the affinity of L-cys towards arsenite. The optical characterization of GQDs was carried out using UV-Vis absorption spectroscopy, Fourier transform infrared spectroscopy, and fluorescence spectrometry and the structural characterizations were performed using transmission electron microscopy. The fluorescence results showed instantaneous quenching in intensity when the GQDs came in contact with As (III) for all test concentrations over a range from 0.025 ppb to 25 ppb, which covers the permissible limit of arsenic in drinking water. The experimental results suggested excellent sensitivity and selectivity towards As (III).

MORPHOLOGY CONTROLLING AND OPTICAL CHARACTERIZATION OF ZnO NANOMATERIALS

2006 ◽  
Vol 20 (25n27) ◽  
pp. 3635-3639
Author(s):  
YUZHEN LV ◽  
CHUNPING LI ◽  
PING CHE ◽  
LIN GUO ◽  
HUIBIN XU
Keyword(s):  
Room Temperature ◽  
Optical Characterization ◽  
Visible Emission ◽  
Ultraviolet Emission ◽  
Synthetic Process ◽  
Uv Emission ◽  
Zno Nanomaterials ◽  
Solution Route ◽  
Pl Spectrum

Wurtzite ZnO nanomaterials including nanoparticles, nanocolumns and nanorods were successfully synthesized by a solution route. Concentrations of modifying reagent and differences of solvent employed in the synthetic process can effectively adjust the morphologies of the as-grown products. Photoluminescence measurements of the ZnO nanocolumns and nanorods have been carried out at room temperature. A sharp Ultraviolet emission at 386 nm and a weak visible emission centered at 515 nm were observed in the PL spectrum of the nanocolumns, while a UV emission of the nanorods was observed at 377 nm.

STRUCTURAL AND OPTICAL CHARACTERIZATION OF ZnO SINGLE CRYSTALLINE NANOBAMBOOS

2005 ◽  
Vol 19 (15n17) ◽  
pp. 2804-2810 ◽  
Author(s):  
LEI MIAO ◽  
SAKAE TANEMURA ◽  
YASUHIKO HAYASHI ◽  
MASAKI TANEMURA ◽  
RONGPING WANG ◽  
...  
Keyword(s):  
Room Temperature ◽  
Annealing Temperature ◽  
Optical Characterization ◽  
Growth Direction ◽  
Annealed Sample ◽  
Green Band ◽  
Post Annealing ◽  
High Resolution Tem ◽  
Post Annealing Temperature

ZnO nanobamboos and nanowires with diameters of 10–30 nm and lengths of 2–4 μm have been prepared by laser ablation in vacuum with precisely controlled pressure, growth and post-annealing temperature. XRD results show the annealed sample is hexagonal ZnO . Low-magnified TEM observation reveals the annealed sample includes ZnO nanobamboos and nanowires. High resolution TEM image and electron diffraction pattern confirm that the structure of ZnO nanobamboo is regular stacking of Zn and O layers with high crystal quality. The growth direction is determined as along [001] direction (c axis). TEM observations confirm that the formation of bamboo-shape ZnO is due to the stacking fault and cleavage. The bundle of those stacking faults seems to be the origin of the black contrast at the nodes. The uniformity of chemical composition for the nanobamboos is identified by EDS profiles. A strong-narrow UV band centred at 390 nm and a weak-broad green band centred at 515 nm are observed at room temperature in the PL spectrum recorded from the annealed ZnO nanobamboos and nanowires.

MOVPE Growth and optical characterization of high-quality ZnSe-ZnS superlattices using a novel zinc adduct precursor

1994 ◽  
Vol 340 ◽  
Author(s):  
O. Briot ◽  
M. Di Blasio ◽  
T. Cloitre ◽  
N. Briot ◽  
P. Bigenwald ◽  
...  
Keyword(s):  
Gas Phase ◽  
Room Temperature ◽  
Optical Characterization ◽  
Variational Calculation ◽  
Light Hole ◽  
Band Offset ◽  
Conduction Band Offset ◽  
Movpe Growth ◽  
Strained Layer Superlattices

ABSTRACTA novel zinc precursor adduct tetramethylmethylene diamine: dimethylzinc (TMMD:DMZn) has been used to grow ZnSe-ZnS strained layer superlattices by low pressure MOVPE at 300'C. The use of this new precursor leads to improved material purity and lower homogeneous gas phase premature reaction than in the case of dimethylzinc. Optical characterization has been made between liquid helium and room temperature. The 2K photoluminescence lines range between 2.85 eV and 3.15 eV. The 2K photoluminescence is characterized by a linewidth at half maximum ranging from 13-45 meV. Additional reflectivity and photoreflectance experiments have been carried out to measure light-hole excitons. A variational calculation of the Rydberg energies has been performed using a sophisticated trial function. The experimental data is in agreement with the theoretical value when a small conduction band offset is used.

Electrical and Optical Characterization of InSb Grown on GaAs by MBE

1989 ◽  
Vol 160 ◽  
Author(s):  
Phillip E. Thompson ◽  
James Waterman ◽  
D. Kurtgaskill ◽  
Robert Stahlbush ◽  
Daniel Gammon ◽  
...  
Keyword(s):  
Room Temperature ◽  
Lattice Mismatch ◽  
Optical Characterization ◽  
Layer Growth ◽  
Temperature Dependent ◽  
Carrier Lifetimes ◽  
Capacitance Voltage ◽  
Ir Transmission ◽  
Mis Capacitors

AbstractInSb has been grown on semi-insulating GaAs substrates by molecular beam epitaxy. By growing an InSb buffer layer at 300 C prior to the main InSb layer growth at 420 C, the effect of the 14% lattice mismatch between GaAs and InSb was minimized. A typical 5 µrn InSb film had a room temperature carrier concentration and electron Hall mobility of 2 × 1016/cm3 and 6×104 cm2/Vs, respectively. At 77 K these values became 2 × 1015/cm3 and 1.1 ×105 cm2/Vs. Temperature dependent Hall measurements revealed a peak in the mobility at 85 K and 70 K for the 5 and 10 µm samples. Capacitance-voltage measurements using MIS capacitors produced 77 K carrier concentrations in agreement with the low fieldHall measurements. Carrier lifetimes were determined by photoconductive response measurements. Lifetimes of 20 ns and 50 ns were determined for the 5 and 10 µm films. For comparison, the carrier lifetime in bulk n-type InSb was found to be 200 ns. Optical characterization by room temperature IR transmission spectroscopy showed a broad absorption edge, with an absorption coefficient of 1.4 × 103/cm at a wavelength of 6 µm. Epilayer thickness was determined from observed interference fringes. Raman spectroscopy showed that each epitaxial layer had a spectrum equivalent to that of bulk InSb.

scholarly journals Structural and optical characterization of size controlled silicon nanocrystals in SiO2/SiOxNy multilayers

2011 ◽  
Vol 10 ◽  
pp. 43-48 ◽  
Author(s):  
J. López-Vidrier ◽  
S. Hernández ◽  
A.M. Hartel ◽  
D. Hiller ◽  
S. Gutsch ◽  
...  
Keyword(s):  
Silicon Nanocrystals ◽  
Optical Characterization ◽  
Size Controlled

Optical Characterization of AlInP/GaAs Heterostructures

1993 ◽  
Vol 324 ◽  
Author(s):  
F.G. Johnson ◽  
G.E. Kohnke ◽  
G.W. Wicks
Keyword(s):  
Ground State ◽  
Room Temperature ◽  
Optical Transmission ◽  
Molecular Beam ◽  
Optical Characterization ◽  
Interface Roughness ◽  
Phonon Modes ◽  
Group V ◽  
Longitudinal Acoustic Phonon

AbstractA 45 period GaAs/A10.54In0.46P superlattice was grown by molecular beam epitaxy using valved solid-sources to supply both the arsenic (As4) and the phosphorus (P2) group V fluxes. The room temperature optical transmission spectrum shows evidence of ground state excitons. Higher energy confined states are exhibited in photovoltage and photoreflectance spectra. Doublets corresponding to the m≈1 through m≈7 folded longitudinal-acoustic phonon modes are observed in the Raman spectrum. Analysis of these phonon doublets enables the structure of the superlattice to be determined. The interface roughness was found to be approximately 2 monolayers, and the layer thicknesses were determined to be 82 Å GaAs and 48 Å A10.54In0.46P.

Structural and Optical Characterization of CdSe Films Grown by Chemical Bath Deposition

2011 ◽  
Vol 691 ◽  
pp. 119-126 ◽  
Author(s):  
J.R. Aguilar-Hernández ◽  
A. Espinosa-Bustamante ◽  
M.A. Hernández-Pérez ◽  
G.S. Contreras-Puente ◽  
M. Cárdenas-García ◽  
...  
Keyword(s):  
Band Gap ◽  
Cadmium Selenide ◽  
Chemical Bath Deposition ◽  
Room Temperature ◽  
Bulk Material ◽  
Optical Characterization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Radiative Emission

We present in this work experimental results and their analysis concerning the structural and optical characterization of cadmium selenide (CdSe) films grown by the Chemical Bath Deposition (CBD) technique, at different bath temperaturesTd: 0≤Td≤80 °C. Structural characterization was carried out by using X-ray diffraction, whereas optical characterization was done by using optical absorption and photoluminescence spectroscopies. X-ray results showed a change of the crystalline structure as a function ofTd, from the zincblende to wurzite one whenTdincreases from 0 to 80 °C. The respective band-gap,Eg,was calculated from the absorption spectrum giving rise to values in the range 1.85 to 2.30 eV, as a function also ofTd. Thses values are higher than the well accepted value of 1.75 eV for the CdSe bulk material. The radiative emission was analyzed throughout the photoluminescence (PL) spectra. All samples showed radiative emission above the band-gap, at room temperature, this radiative emission having a dependence on the pressure inside the cryostat. A quenching of the PL signal is observed when the pressure is decreased at values as low as 60 mTorr.

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