Role of occupieddbands in the dynamics of excited electrons and holes in Ag

Abstract

The role that occupied d bands play in the inelastic lifetime of bulk and surface states in Ag is investigated from the knowledge of the quasiparticle self-energy. In the case of bulk electrons, sp bands are taken to be free-electron like. For surface states, the surface band structure of sp states is described with the use of a realistic one-dimensional hamiltonian. The presence of occupied d states is considered in both cases by introducing a polarizable background. We obtain inelastic lifetimes of bulk electrons that are in good agreement with first-principles band-structure calculations. Our surface-state lifetime calculations indicate that the agreement with measured lifetimes of both crystal-induced and image-potential induced surface states on Ag(100) and Ag (111) is considerably improved when the screening of d electrons is taken into account.

Momentum-resolved electron dynamics of image-potential states on Cu and Ag surfaces

“…(2)], which contains contributions from bulk, surface, and image-potential states. It was shown 43,54 that ImW decays when moving away from the surface to vacuum. Since rare-gas spacer layers push the image-potential state electron into the vacuum, the intraband scattering rate decreases through the decrease of ImW .…”

“…Although this opens a further inelastic decay channel for electrons in the image-potential states, it has been shown that the highly nonlocal character of the self-energy near the surface leads astonishingly to an increase of their lifetime at the point of silver surfaces. 42,43 A priori the surface plasmon excitation channel on silver is also expected to play an important role for k = 0.…”

Decay of electronic excitations at metal surfaces

“…An extension of the s-d-polarization model first proposed by Liebsch [77] for a jellium model to the model potential described above (see Section 2.2) [45] has been made recently by López-Bastidas et al [78] and García-Lekue et al [75,79]. In this case, the electron states are taken to be described by the eigenvalues and eigenfunctions of the model Hamiltonian and this bounded assembly of electrons is then immersed in a polarizable background of d-electrons which extends from deep into the solid up to a certain plane z ¼ z d .…”

“…0Þ for Ag, Au and Cu are 4, 6.6 and 5.6, respectively [52,75]. García-Lekue et al [75] have analyzed the impact of d-electron screening and concluded that, in the long-wavelength limit (q ! 0) the increase of the lifetimes is negligible.…”

“…In Ag, however, both the surface and bulk plasmons have energies around 3.8 eV. These collective excitations can influence the decay of image-potential states via the participation of d-electrons in the screening of electron-electron interaction [75,79]. The effect of d-electrons in the screening can be taken into account by using the s-d-polarization model of Liebsch [77,309] (see Eq.…”