相关论文: Dark Excitons in Carbon Nanotubes
The spectrum of large radius exciton in an individual semiconducting single-walled carbon nanotube (SWCNT) is described within the framework of elementary potential model, in which exciton is modeled as bound state of two oppositely charged…
Electron-electron interactions and excitons in carbon nanotubes are locally measured by combining Scanning tunneling spectroscopy and optical absorption in bundles of nanotubes. The largest gap deduced from measurements at the top of the…
We studied the asymmetry between valence and conduction bands in single-walled carbon nanotubes (SWNTs) through the direct observation of spin-singlet transverse dark excitons using polarized photoluminescence excitation spectroscopy. The…
We show that the energy differences between the lowest optical singlet exciton and the lowest triplet exciton in semiconducting single-walled carbon nanotubes with diameter $\sim 1$ nm and graphene nanoribbons with widths $\sim 2$ nm are an…
Semiconductor excitons are commonly seen as hydrogen atom. This analogy requires a unique hole mass. In reality, this is not so due to the complexity of the semiconductor band structure. The precise consequences on the exciton physics of…
We use the macroscopic quantum electrodynamics approach suitable for absorbing and dispersing media to study the properties and role of collective surface excitations --- excitons and plasmons --- in single-wall and double-wall carbon…
Exciton luminescence of a CdSe quantum dot (QD) inserted in a ZnSe nanowire is strongly influenced by the dark exciton states. Because of the small size of these QDs (2-5nm), exchange interaction between hole and electron is highly enhanced…
Free electrons or holes can mediate the nonradiative recombination of excitons in carbon nanotubes. Kinematic constraints arising from the quasi one-dimensional nature of excitons and charge carriers lead to a thermal activation barrier for…
Trion states of three correlated particles (e.g., two electrons and one hole) are essential to understand the optical spectra of doped or gated nanostructures, like carbon nanotubes or transition-metal dichalcogenides. We develop a…
We show that for the very same reason that excitons are bright, i.e. coupled to photons, they have a higher energy than dark excitons, even for electrons spatially separated from holes, such as in a double quantum well. Indeed, the same…
Optical and electronic phenomena in solids arise from the behaviour of electrons and holes (unoccupied states in a filled electron sea). Electron-hole symmetry can often be invoked as a simplifying description, which states that electrons…
We study the band-edge exciton fine structure and in particular its bright-dark splitting in colloidal semiconductor nanocrystals by four different optical methods based on fluorescence line narrowing and time-resolved measurements at…
We investigate electric-field induced redshifts of photoluminescence from individual single-walled carbon nanotubes. The shifts scale quadratically with field, while measurements with different excitation powers and energies show that…
Shallow hole-doping in small diameter single-wall carbon nanotubes by H$_2$O$_2$ is shown to result in delocalized excited state quenching with no effects on the ground state absorption spectrum. To account for this process, the…
Fifty years ago Walter Kohn speculated that a zero-gap semiconductor might be unstable against the spontaneous generation of excitons---electron-hole pairs bound together by Coulomb attraction. The reconstructed ground state would then open…
Often a modification of microscopic symmetry in a system can result in a dramatic change in its macroscopic properties. Here we report that symmetry breaking by a tube-threading magnetic field can drastically increase the photoluminescence…
The optical properties of transition metal dichalcogenide monolayers such as the two-dimensional semiconductors MoS$_2$ and WSe$_2$ are dominated by excitons, Coulomb bound electron-hole pairs. The light emission yield depends on whether…
An analytical expression is obtained for the biexciton binding energy as a function of the inter-exciton distance and binding energy of constituent quasi-one-dimensional excitons in carbon nanotubes. This allows one to trace biexciton…
We study theoretically the interactions of excitonic states with surface electromagnetic modes of small-diameter (~1 nm) semiconducting single-walled carbon nanotubes. We show that these interactions can result in strong…
We have studied emission properties of high-density excitons in single-walled carbon nanotubes through nonlinear photoluminescence excitation spectroscopy. As the excitation intensity was increased, all emission peaks arising from different…