We demonstrate that confinement-induced intervalley splittings of electron energy levels in PbSe and PbS nanocrystals are sensitive to the arrangement of atoms within a nanocrystal. The splittings are strongly suppressed for stoichiometric nanocrystals of $T_d$ point symmetry lacking a center of inversion as opposed to nonstoichiometric nanocrystals of $O_h$ point symmetry having an inversion center. Our findings are supported by both atomistic $s{p}^3{d}^5{s}^{*}$ tight-binding calculations and a symmetry analysis.

• Received 8 November 2011

DOI:https://doi.org/10.1103/PhysRevB.86.035324