Journal ArticleDOI
Higher excited electronic states in clusters of ZnSe, CdSe, and ZnS: Spin‐orbit, vibronic, and relaxation phenomena
Reads0
Chats0
TLDR
In this article, a comparison of sulfide and selenide spectra enables observation of the effect of changes in the highest occupied molecular orbitals upon cluster electronic properties, and it is shown that the energy spectrum of discrete hole states is controlled by the spin-orbit energy and the isotropic hole mass in small, highly symmetrical clusters.Abstract:
Metal selenide clusters have been made and characterized, using the arrested precipitation colloidal technique. A comparison of sulfide and selenide spectra enables observation of the effect of changes in the highest occupied molecular orbitals upon cluster electronic properties. The first and second excited electronic states are both observed as a function of size in ZnSe clusters. The systematic dependence of the spectra lead to assignment of the higher state to a 1S‐type hole based upon the split‐off valence band. It is shown that the energy spectrum of discrete hole states is controlled by the spin‐orbit energy and the isotropic hole mass in small, highly symmetrical clusters. This result contrasts with the heavy hole and light hole states observed for planar confinement. In ≂ 20 A diameter ZnS clusters, there is a strong vibronic temperature dependence in the excited state spectra, while in clusters of smaller gap materials such vibronic effects are very minor. We conjecture that lifetime broadening ...read more
Citations
More filters
Journal ArticleDOI
Shape Control of Semiconductor and Metal Oxide Nanocrystals through Nonhydrolytic Colloidal Routes
TL;DR: The currently proposed shape-guiding mechanisms are presented and the important pioneering studies on the assembly of shape-controlled nanocrystals into ordered superlattices and the fabrication of prototype advanced nanodevices are discussed.
Journal ArticleDOI
Low-dimensional systems: quantum size effects and electronic properties of semiconductor microcrystallites (zero-dimensional systems) and some quasi-two-dimensional systems
TL;DR: In this paper, a review is concerned with quantum confinement effects in low-dimensional semiconductor systems, focusing on the optical properties, including luminescence, of nanometre-sized microcrystals.
Journal ArticleDOI
Quantum crystallites and nonlinear optics
TL;DR: In this paper, a review and analysis of the optical properties of quantum crystallites, with principal emphasis on the electro-optic Stark effect and all optical third order nonlinearity is presented.
References
More filters
Journal ArticleDOI
Electron–electron and electron‐hole interactions in small semiconductor crystallites: The size dependence of the lowest excited electronic state
TL;DR: In this paper, the excited electronic states of semiconductor crystallites sufficiently small (∼50 A diam) that the electronic properties differ from those of bulk materials were modeled, and an approximate formula was given for the lowest excited electronic state energy.
Journal ArticleDOI
Diffusion-limited aggregation, a kinetic critical phenomenon
Abstract: A model for random aggregates is studied by computer simulation The model is applicable to a metal-particle aggregation process whose correlations have been measured previously Density correlations within the model aggregates fall off with distance with a fractional power law, like those of the metal aggregates The radius of gyration of the model aggregates has power-law behavior The model is a limit of a model of dendritic growth
Journal ArticleDOI
A simple model for the ionization potential, electron affinity, and aqueous redox potentials of small semiconductor crystallites
TL;DR: In this article, the photochemical redox potential of one carrier, as a function of the size of the crystal, has been studied in the case of a small number of electrons.
A simple model for the ionization potential, electron affinity, and aqueous redox potentials of small semiconductor crystallites
Abstract: Large semiconductor crystals have intrinsic electronic properties dependent upon the bulk band structure. As the crystal becomes small, a new regime is entered in which the electronic properties (excited states, ionization potential, electron affinity) should be strongly dependent upon the electron and hole in a confined space. We address the possibility of a shift in the photochemical redox potential of one carrier, as a function of crystallite size. As a semiquantitative guide, one might expect a shift on the order of h2/8em*R2 due to the kinetic energy of localization in the small crystallite. We model the elementary quantum mechanics of a charged crystallite using (a) the effective mass approximation, (b) an electrostatic potential for dielectric polarization, and (c) penetration of the carrier outside the crystallite in a cases of small effective mass. Shifts of several tenths of an eV appear possible in crystallites of diameter 50 A. The carrier charge density reside near the crystallite surface if ...
Journal ArticleDOI
Quantum States of Confined Carriers in Very Thin Al x Ga 1 − x As -GaAs- Al x Ga 1 − x As Heterostructures
TL;DR: In this article, a simple rectangular potential well with a depth of ≈088ΔE g, where ΔE g is the difference in the semiconductor energy gaps is defined.