C. Flytzanis

Bio: C. Flytzanis is an academic researcher from Centre national de la recherche scientifique. The author has contributed to research in topics: Faraday effect & Nonlinear optics. The author has an hindex of 13, co-authored 28 publications receiving 1182 citations.

Optical nonlinearities of small metal particles: surface-mediated resonance and quantum size effects

Abstract: Time- and frequency-dependent measurements of optical phase conjugation in gold colloids are reported. It is shown that the nonlinear response is fast on a 5-psec time scale and can be assigned to the electrons of the small metal spheres. The frequency-dependent measurements were performed in the neighborhood of the surface-plasma resonance and give experimental evidence of the validity of our resonant enhancement model. We also report the first model calculation of the third-order Kerr susceptibility of small metal particles. The dominant terms of this electric-dipole contribution are emphasized and lead to an expression for χ(3) that varies roughly as the inverse third power of the radius of the particles. This model accounts for the observed anisotropy of this susceptibility and provides an estimate of its magnitude, in agreement with the measured values. The limited size effect on the linear susceptibility is also discussed.

Time‐resolved measurements of carrier recombination in experimental semiconductor‐doped glasses: Confirmation of the role of Auger recombination

Abstract: Using three different time‐resolved techniques: degenerate four wave mixing, nonlinear absorption, and luminescence, we show that, for our CdSxSe1−x‐doped glasses, under high excitation conditions, Auger recombination is the dominant recombination process. This explains the broad range of luminescence lifetimes previously reported. After photodarkening, we also observe a reduction in the nonradiative lifetime.

Quantum‐confined Stark effect in very small semiconductor crystallites

Abstract: Experimental study of the change δα in the absorption spectrum due to a static electric field is reported for very small CdSSe crystallites. We observe oscillations of δα as a function of the wavelength, which are well explained as a Stark effect for the quantized electronic levels. A perturbation calculation is performed, which gives good theoretical fits of the experimental curves.

Optical nonlinearities in semiconductor-doped glasses.

Abstract: We present a phenomenological theory of the intensity-dependent dielectric function of semiconductor-doped glasses near the absorption edge. It is shown that efficient phase conjugation by degenerate four-wave mixing should be possible in these materials.

Time‐resolved direct observation of Auger recombination in semiconductor‐doped glasses

Abstract: Using time‐resolved techniques, absorption recovery, and degenerate four‐wave mixing, we directly observe the nonexponential intensity‐dependent recombination of free carriers photoexcited in semiconductor‐doped glasses. We assign this behavior to Auger recombination.

Chemistry and properties of nanocrystals of different shapes.

Abstract: The interest in nanoscale materials stems from the fact that new properties are acquired at this length scale and, equally important, that these properties * To whom correspondence should be addressed. Phone, 404-8940292; fax, 404-894-0294; e-mail, mostafa.el-sayed@ chemistry.gatech.edu. † Case Western Reserve UniversitysMillis 2258. ‡ Phone, 216-368-5918; fax, 216-368-3006; e-mail, burda@case.edu. § Georgia Institute of Technology. 1025 Chem. Rev. 2005, 105, 1025−1102

Optical properties and ultrafast dynamics of metallic nanocrystals.

Abstract: Noble metal particles have long fascinated scientists because of their intense color, which led to their application in stained glass windows as early as the Middle Ages. The recent resurrection of colloidal and cluster chemistry has brought about the strive for new materials that allow a bottoms-up approach of building improved and new devices with nanoparticles or artificial atoms. In this review, we discuss some of the properties of individual and some assembled metallic nanoparticles with a focus on their interaction with cw and pulsed laser light of different energies. The potential application of the plasmon resonance as sensors is discussed.

Quantization of multiparticle auger rates in semiconductor quantum dots

Abstract: We have resolved single-exponential relaxation dynamics of the 2-, 3-, and 4-electron-hole pair states in nearly monodisperse cadmium selenide quantum dots with radii ranging from 1 to 4 nanometers. Comparison of the discrete relaxation constants measured for different multiple-pair states indicates that the carrier decay rate is cubic in carrier concentration, which is characteristic of an Auger process. We observe that in the quantum-confined regime, the Auger constant is strongly size-dependent and decreases with decreasing the quantum dot size as the radius cubed.

Low-dimensional systems: quantum size effects and electronic properties of semiconductor microcrystallites (zero-dimensional systems) and some quasi-two-dimensional systems

Abstract: This review is concerned with quantum confinement effects in low-dimensional semiconductor systems. The emphasis is on the optical properties, including luminescence, of nanometre-sized microcrysta...