Linear and nonlinear transmission of CuxS quantum dots

Abstract

CuxS nanocrystals (NC’s) are reported. The samples are prepared by a CdS-to-CuxS chemical conversion from the glasses originally containing CdS NC’s. A room-temperature linear absorption of the converted samples shows several well resolved peaks with spectral positions from red to blue. These spectral features are explained by size quantization within CuxS NC’s (∼4 nm radius) with different copper deficiency [x is in the range from 1.8 (digenite) to 2 (chalcosite)]. A strong bleaching of the samples with a 3-ns relaxation is observed in the pump–probe measurements. A high value of the third-order nonlinear susceptibility (∼10−7 esu) is derived from the nonlinear transmission spectra.

Synthesis of Mesostructured Copper Sulfide by Cation Exchange and Liquid‐Crystal Templating

“…Konenkamp et al [2] and Alivisatos et al [4] have successfully utilized the ion exchange methods to fully transform the chemical composition of simple nanostructured inorganic materials while retaining their shapes. Although the exact mechanism by which the ions exchange while retaining the overall structure is still shown to possess interesting optical properties, [3] therefore, successful synthesis of mesostructured Cu x S shows a broad band with λ max at 375 nm, which, according to previously published results, [20,21] is indicative of Cu 2 S nanoparticle formation. It is interesting to note that we specifically observed an absorption band for Cu 2 S, when in fact Cu 2+ ions were added to the mesostructured CdS.…”

“…[2][3][4] Templating of supramolecular assemblies of surfactants and amphiphilic polymers has already proven to be a powerful technique in synthesizing various inorganic structures. Namely, numerous examples of mesostructured metal oxides (SiO 2 , TiO 2 , WO 3 , etc.)…”

Optical nonlinearities and carrier trapping dynamics in CdS and CuxS nanocrystals

“…Depending on the copper deficiency, the energy band gap in copper sulfide varies from ∼ 1.2 eV for x = 2 (chalcosite) [11,12] to ∼ 1.5 eV for x = 1.8 (digenite) [13], accompanied by a transformation of an originally indirect-gap semiconductor to a direct-gap one. These interesting properties, as well as a small electron mass [10] resulting in large confinement-induced energy shifts, provide a broad phase/size controlled tuning range and give an opportunity to compare the effects of 3D confinement on nonlinear optical properties in direct-and indirectgap semiconductors. We concentrate on Cu x S NCs in two phases with x = 1.8 and 2 which exhibit, direct and indirect energy gaps in the bulk form, respectively.…”

“…These techniques provide complementary information on carrier dynamics and allow us to separately observe electron and hole relaxation paths. In the second part of the paper, we report on ultrafast optical nonlinearities in new type of NC materials-glasses doped with copper sulfide NCs [10]. Depending on the copper deficiency, the energy band gap in copper sulfide varies from ∼ 1.2 eV for x = 2 (chalcosite) [11,12] to ∼ 1.5 eV for x = 1.8 (digenite) [13], accompanied by a transformation of an originally indirect-gap semiconductor to a direct-gap one.…”

Study of the iron nanoparticles phase transformation during thermal annealing

“…Основными преимуществами термической об-работки являются: снижение внутреннего напряжения, воз-никающего при получении, повышение прочностных свойств за счет снижения количества дефектов и изменению дефект-ной структуры, структура становится более упорядоченной и устойчивой к внешним воздействиям [13,14]. Однако про-должительность термической обработки по времени может сыграть двоякую роль в изменении проводящих свойств, так как длительный термический отжиг приводит к необратимо-му изменению физических параметров [15,16].…”