Size-dependent change in interband absorption of Pb particles: Effects of surface atoms

Abstract

publisherInterband absorption of Pb-island films, consisting of Pb particles larger than about 50 A in diameter, has been measured in the photon energy range of 0.5-6.5 eV. The interband absorption located from 4.23±0.07 to 4.44±0.06 eV, the initial state for which is positioned at the bottom of the conduction bands, disappeared below about 300 A in diameter. The interband absorption located from 3.68±0.04 to 3.78±0.04 eV was shifted to higher energies with decreasing particle size below about 300 A in diameter, and became weaker with shift. The shift causes the initial state to be present in the lower portion of the conduction bands. The disappearance and the weakening are due to the decrease in the density of states (DOS) at the lower portion of the conduction bands. Such a decrease can be attributed to the effect of the reduced coordination number of surface atoms on the DOS of the conduction bands

Structural Characterization, Optical Properties, and Phase Transitions of In1–xSnx Alloy Thin Films

“…The peaks in the absorption spectra due to interband transitions show a red shift compared with those of the bulk material. An experimental study of interband absorption of Pb particles showed that conduction-band narrowing is found along with changes in the distribution of the density of states of the conduction bands …”

“…An study of interband absorption of Pb particles showed that conduction-band narrowing is found along with changes in the distribution of the density of states of the conduction bands. 46 On the other hand, in bulk metals, the contraction of lattice constants causes the broadening of energy bands. 47 The lattice constants of metal particles contract as the particle size becomes smaller because of the hydrostatic pressure coming from the particle surface stress.…”

Size-dependent change in energy bands of nanoparticles of white tin

“…Thus, energy bands of metal particles narrow as the particle size is decreased. An experimental study 3 of interband absorption of Pb particles has reported that the conduction-band narrowing is attended with the change in the distribution of the density of states of the conduction bands.…”

Tunable variation of optical properties of polymer capped gold nanoparticles

“…Hence, gold seems to be most ideal system to study the effect of quantum confinement and surface effects on interband absorption. Except for some work by Yamaguchi et al [17], and some more recent work on lead and tin clusters [28,35], systematic study has not been performed on the size dependance of interband dielectric function, mainly due to lack of analytical expression ( equivalent to Drude free electron term ) describing it's behavior. Recently, an…”

“…However there is some controversy [8] about the interpretation of the optical properties of such metal cluster films as it was not clear to what extent the observed spectra depended on the morphology of the clusters. In addition, no clear trends exists in terms of width and position of the centroid of the valence bands as a function of size and surface effects [28,29]. Some effort was made to calculate the optical properties of metal clusters by modeling the inter band part of dielectric function with a single Lorentzian oscillator.…”