Enhancement in green and NIR emissions of Er3+ by energy transfer from ZnSe nanoparticles in borosilicate glass

Microanalysis by EELS has been developing rapidly and though the general form of the spectrum is now understood there is a need to put the technique on a more quantitative basis (1,2). Certain aspects important for microanalysis include: (i) accurate determination of the partial cross sections, σx(α,ΔE) for core excitation when scattering lies inside collection angle a and energy range ΔE above the edge, (ii) behavior of the background intensity due to excitation of less strongly bound electrons, necessary for extrapolation beneath the signal of interest, (iii) departures from the simple hydrogenic K-edge seen in L and M losses, effecting σx and complicating microanalysis. Such problems might be approached empirically but here we describe how computation can elucidate the spectrum shape.The inelastic cross section differential with respect to energy transfer E and momentum transfer q for electrons of energy E0 and velocity v can be written as

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Nanostructure of semiconductor quantum dots in a borosilicate glass matrix by complementary use of HREM and AEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100176770 ◽

1990 ◽

Vol 48 (4) ◽

pp. 728-729

Author(s):

M.J. Kim ◽

L.C. Liu ◽

S.H. Risbud ◽

R.W. Carpenter

Keyword(s):

Quantum Dots ◽

Borosilicate Glass ◽

Glass Matrix ◽

Optical Switching ◽

Response Times ◽

Fast Response ◽

Processing Technique ◽

Internal Stresses ◽

Electron Hole ◽

Spatial Dimensions

When the size of a semiconductor is reduced by an appropriate materials processing technique to a dimension less than about twice the radius of an exciton in the bulk crystal, the band like structure of the semiconductor gives way to discrete molecular orbital electronic states. Clusters of semiconductors in a size regime lower than 2R {where R is the exciton Bohr radius; e.g. 3 nm for CdS and 7.3 nm for CdTe) are called Quantum Dots (QD) because they confine optically excited electron- hole pairs (excitons) in all three spatial dimensions. Structures based on QD are of great interest because of fast response times and non-linearity in optical switching applications.In this paper we report the first HREM analysis of the size and structure of CdTe and CdS QD formed by precipitation from a modified borosilicate glass matrix. The glass melts were quenched by pouring on brass plates, and then annealed to relieve internal stresses. QD precipitate particles were formed during subsequent "striking" heat treatments above the glass crystallization temperature, which was determined by differential thermal analysis.

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Gas Kinetics and Energy Transfer

10.1039/2051-1477 ◽

2015 ◽

Keyword(s):

Energy Transfer ◽

Gas Kinetics

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