6,655 research outputs found
Exciton Binding Energy of Monolayer WS2
The optical properties of monolayer transition metal dichalcogenides (TMDC)
feature prominent excitonic natures. Here we report an experimental approach
toward measuring the exciton binding energy of monolayer WS2 with linear
differential transmission spectroscopy and two-photon photoluminescence
excitation spectroscopy (TP-PLE). TP-PLE measurements show the exciton binding
energy of 0.71eV around K valley in the Brillouin zone. The trion binding
energy of 34meV, two-photon absorption cross section 4X10^{4}cm^{2}W^{-2}S^{-1}
at 780nm and exciton-exciton annihilation rate around 0.5cm^{2}/s are
experimentally obtained.Comment: 5page,3 figure
Ricci flow on compact K\"ahler manifolds of positive bisectional curvature
We announce a new proof of the uniform estimate on the curvature of solutions
to the Ricci flow on a compact K\"ahler manifold with positive
bisectional curvature. In contrast to the recent work of X. Chen and G. Tian,
our proof of the uniform estimate does not rely on the exsitence of
K\"ahler-Einstein metrics on , but instead on the first author's Harnack
inequality for the K\"ahler-Ricc flow, and a very recent local injectivity
radius estimate of Perelman for the Ricci flow.Comment: 4 page
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