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تسجيل مستخدم جديدInvestigation of indirect excitons in bulk $2H$-MoS$_2$ using transmission electron energy-loss spectroscopy
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We have investigated indirect excitons in bulk $2H$-MoS$_2$ using transmission electron energy-loss spectroscopy. The electron energy-loss spectra were measured for various momentum transfer values parallel to the $Gamma$K and $Gamma$M directions of the Brillouin zone. The results allowed the identification of the indirect excitons between the valence band K$_{mathrm{v}}$ and conduction band $Lambda_{mathrm{c}}$ points, the $Gamma_{mathrm{v}}$ and K$_{mathrm{c}}$ points as well as adjacent K$_{mathrm{v}}$ and K$^{prime}_textrm{c}$ points. The energy-momentum dispersions for the K$_{mathrm{v}}$-$Lambda_{mathrm{c}}$, $Gamma_{mathrm{v}}$-K$_{mathrm{c}}$ and K$_{mathrm{v1}}$-K$^{prime}_textrm{c}$ excitons along the $Gamma$K line are presented. The former two transitions exhibit a quadratic dispersion which allowed calculating their effective exciton masses based on the effective mass approximation. The K$_mathrm{v1}$-K$^{prime}_textrm{c}$ transition follows a more linear dispersion relationship.
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