Nanometer-Scale Imaging

Author(s):  
C. Julian Chen

This chapter discusses the imaging mechanism of STM at the nanometer scale, where the features of interest are of about one nanometer and up. Using an s-wave tip model, using the Bardeen tunneling theory, Tersoff and Hamann showed that the STM image in this case is tip-independent: it is determined by the local density of states of the bare sample surface at Fermi level, taken at the center of curvature of the tip. The Tersoff-Hamann model has found numerous applications in interpreting the STM images, from the superstructure of surface reconstruction to the confined or scattered waves of the surface states. However, as shown by Tersoff and Hamann in their original papers, for features much smaller than one nanometer, such as at the atomic features of 0.3 nm, the non-spherical electronic states of the tip could play a significant role and thus cannot be overlooked.

Author(s):  
Valentina Krachmalnicoff ◽  
Dorian Bouchet ◽  
Rémi Carminati ◽  
Sébastien Bidault ◽  
Ignacio Izeddin ◽  
...  

Hyomen Kagaku ◽  
1989 ◽  
Vol 10 (6) ◽  
pp. 416-420
Author(s):  
Norimasa ITO ◽  
Kazuyuki EDAMOTO ◽  
Eizo MIYAZAKI

2005 ◽  
Vol 19 (25) ◽  
pp. 1285-1294 ◽  
Author(s):  
JOSÉ A. GASCÓN ◽  
HORACIO M. PASTAWSKI

In metallic nanoparticles, shifts in the ionization energy of surface atoms with respect to bulk atoms can lead to surface bands. Within a simple Tight Binding model we find that the projection of the electronic density of states on these sites presents two overlapping structures. One of them is characterized by the level spacing coming from bulk states and the other arises from the surface states. In very small particles, this effect contributes to an over-broadening of the NMR absorption spectra, determined by the Knight shift distribution of magnetic nuclei. We compare our calculated Knight shifts with experiments on aluminum nanoparticles, and show that the deviation of the scaling law as a function of temperature and particle size can be explained in terms of surface states.


Author(s):  
Le The Anh ◽  
Francesca Celine I. Catalan ◽  
Yousoo Kim ◽  
Yasuaki Einaga ◽  
Yoshitaka Tateyama

Dependence of DOS on the boron's positions on a diamond(111) surface. In the bulk, boron interacts with carbon sp3 and shows p-type characters. On the surface, boron strongly interacts with carbon sp2 and exhibits surface states in the midgap.


2014 ◽  
Vol 1015 ◽  
pp. 155-158
Author(s):  
Wei Hua Wang ◽  
Cui Lan Zhao ◽  
Xin Jun Ma

The centre Au-doped armchair graphene nanoribbons (AGNRs) are investigated using the local density approximation based on density function theory. The charge density, electronic energy band and project density of states of centre Au-doped AGNRs are calculated. Our results indicate the charge density is transferred between C and Au atoms and mainly located on the Au atoms. The centre Au-doped AGNRs are an indirect band gap semiconductor with an energy gap of 1.046 eV. The Fermi level is located on valence band so that the AGNRs of doping Au become into degenerate semiconductor. The project density of states is calculated to reveal localization and hybridization between C-2pand Au-6s, 5delectronic states. The localization and hybridization are much stronger in the valence band. The hybridization between C-2pand Au-6pelectronic states are strongly in the conduction band.


Respuestas ◽  
2018 ◽  
Vol 23 (1) ◽  
pp. 13
Author(s):  
Hernan Javier Herrera ◽  
A. Rubio Ponce ◽  
D. Olguín

 La motivación del presente trabajo se fundamenta en la importancia del Paladio en procesos de catálisis y sus propiedades electrónicas. En tal sentido, se presenta un estudio detallado de la estructura electrónica de bandas del Paladio en la dirección cristalográfica (111). De tal manera, se verificó que la densidad local de estados proyectada en el volumen, concordara con los resultados obtenidos para el caso del medio infinito previamente reportados, para ello, se realizó un estudio detallado de diferentes estados de superficie y estados resonantes característicos del Paladio en la dirección cristalográfica (111). Se halló que los resultados obtenidos se comparan con los valores publicados en la literatura, y se hizo la predicción de diferentes estados no reportados aún.Palabras clave:  Estados de superficie, estados resonantes, estructura electrónica de bandas. AbstractThe motivation of this work is based on the importance of Palladium in processes such as catalysis and hence the need to know its electronic properties. We present a detailed study of the electronic structure of Palladium bands in the crystallographic direction (111). First we verify that the local density of states, projected in the volume, agrees with the results obtained for the case of the infinite medium previously reported. Next, a detailed study is made of different surface states and characteristic resonant states of the Palladium in the crystallographic direction (111). It was found that the results obtained are compared with the values published in the literature, and the prediction of different states not yet reported is made.Keywords: Surface states, resonant states, local density of states, bulk projected electronic band structure. ResumoA motivação do presente trabalho baseia-se na importância do paládio nos processos de catálise e suas propriedades eletrônicas. A este respeito, um estudo detalhado da estrutura eletrônica das bandas de paládio na direção cristalográfica (111) é apresentado. Desta forma, verificou-se que a densidade local de estados projetados no volume, vai concordar com os resultados obtidos para o caso do meio infinito relatado anteriormente, para isso, foi feito um estudo detalhado dos diferentes estados de superfície e estados ressonantes característicos do paládio. na direção cristalográfica (111). Verificou-se que os resultados obtidos são comparados com os valores publicados na literatura, e a predição dos diferentes estados ainda não relatados foi feita.Palavras-chave:  Estados de superfície, estados ressonantes, estrutura de banda eletrônica. 


2000 ◽  
Vol 69 (5) ◽  
pp. 1472-1476
Author(s):  
Yasunari Tanuma ◽  
Yukio Tanaka ◽  
Masao Ogata ◽  
Satoshi Kashiwaya

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