Resonant Raman scattering in GaAs/AlAs superlattices under electric fields

Virtual Trions in the Photoluminescence of Monolayer Transition-Metal Dichalcogenides

Photoluminescence experiments from monolayer transition-metal dichalcogenides often show that the binding energy of trions is conspicuously similar to the energy of optical phonons. This enigmatic coincidence calls into question whether phonons are involved in the radiative recombination process. We address this problem, unraveling an intriguing optical transition mechanism. Its initial state is a localized charge (electron or hole) and delocalized exciton. The final state is the localized charge, phonon, and photon. In between, the intermediate state of the system is a virtual trion formed when the localized charge captures the exciton through emission of the phonon. We analyze the difference between radiative recombinations that involve real and virtual trions (i.e., with and without a phonon), providing useful ways to distinguish between the two in experiment.

ANOMALOUS ANISOTROPY OF RESONANT RAMAN SCATTERING IN OPEN ZnCdSe/ZnSe NANOWIRES

Anomalous strong linear anisotropy of resonant Raman scattering in open ZnCdSe / ZnSe nanowires has been found. The anisotropy value is more than twice as that due to the anisotropy of exciton–photon interaction which is the characteristic for open nanowires. It is suggested that the anomalous anisotropy is connected with different probability of Frohlich exciton–LO phonon interaction at scattering via transverse and longitudinal exciton states.

LOCALIZED OPTICAL PHENOMENA AND THE CHARACTERIZATION OF MATERIALS INTERFACES

▪ Abstract  This review focuses on the characterization of interfaces, specifically on the optical methods of characterization that utilize some form of spatial localization to circumvent the special problems accruing to interfaces. Experiments utilizing radiation in only the infrared through the ultraviolet regions of the electromagnetic spectrum are considered. We specifically exclude the vast and important array of experimental techniques that utilize the vacuum ultraviolet and X-ray spectral regions. In addition, the interfaces considered are those composed of solids with liquids, thin films, and other solids, thus largely ignoring the literature of ultrahigh vacuum surface science.