Narrow Results

Electron Raman scattering (ERS) is investigated in a CdS cylindrical spherical dot (QD). The different cross-section (DCS) is calculated as a function of the scattering frequency and the size of QD. Single parabolic conduction and valence bands are assumed. Singularities in the spectrum are found and interpreted. The selection rules for the processes are also studied. The ERS studied here can be used to provide direct information about the electron band structure of these systems.

In this paper, the interface phonons in a core-shell quantum dot are theoretically studied by a resonant Raman scattering (RRS) process. Fröhlich electron–phonon interaction is considered in the framework of the dielectric continuum approach. The Raman peaks are found to be sensitive to the size of strongly confined shell. The shift of the Raman resonant peaks is a consequence of the change of observed dispersion of the phonon frequency. The Raman intensity changes in the system with shell thickness, originating from the competition between the spacial distribution of electron wave function and the number of phonons joining in the RRS process. The analysis of the Raman spectra gives a physical explanation to the size-selective nature of the Raman process and some experimental results.

Recently observed heavy quark exotic XYZ mesons stimulated heated discussions about their structures. In the molecule picture, we discuss the spin of the heavy quark pair in an S-wave meson-antimeson state, whose value is either 1 or 0. We find two rules that the spin is only 1 in the heavy quark limit. From the conservation of the spin, one may analyze the charmonium products from strong decays. The selection rules give constraints on the products.