This work studies extinction properties of ZnSe quantum dots terminated with either Se-surface or Zn-surface (Se-ZnSe or Zn-ZnSe QDs).In addition to commonly observed photoluminescence quenching by anionic surface sites,Se-ZnSe QDs are found to show drastic signatures of Se-surface states in their UV-visible (Vis) absorption spectra.Similar to most QDs reported in literature,monodisperse Zn-ZnSe QDs show sharp absorption features and blue-shifted yet steep absorption edge respect to the bulk bandgap.However,for monodisperse Se-ZnSe QDs,all absorption features are smeared and a low-energy tail is identified to extend to an energy window below the bulk ZnSe bandgap.Along increasing their size,a cyclic growth of ZnSe QDs switches their surface from Zn-terminated to So-terminated ones,which confirms that the specific absorption signatures are reproducibly repeated between those of two types of the QDs.Though the extinction coefficients per unit of Se-ZnSe QDs are always larger than those of Zn-ZnSo QDs with the same size,both of them approach the same bulk limit.In addition to contribution of the lattice,extinction coefficients per nanocrystal of Zn-ZnSe QDs show an exponential term against their sizes,which is expected for quantum-confinement enhancement of electron-hole wavefunction overlapping.For Se-ZnSe QDs,there is the third term identified for their extinction coefficients per nanocrystal,which is proportional to the square of size of the QDs and consistent with surface contribution.