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First-principles investigation of Ag-doped gold nanoclusters.

Zhang XD, Guo ML, Wu D, Liu PX, Sun YM, Zhang LA, She Y, Liu QF, Fan FY - Int J Mol Sci (2011)

Bottom Line: The electronic structure of a stable Au(20) cluster can be modulated by incorporating Ag, and the HOMO-LUMO gap of Au(20-) (n)Ag(n) clusters is modulated due to the incorporation of Ag electronic states in the HOMO and LUMO.Furthermore, the results of the imaginary part of the dielectric function indicate that the optical transition of gold clusters is concentration-dependent and the optical transition between HOMO and LUMO shifts to the low energy range as the Ag atom increases.These calculated results are helpful for the design of gold cluster-based biomaterials, and will be of interest in the fields of radiation medicine, biophysics and nanoscience.

View Article: PubMed Central - PubMed

Affiliation: Tianjin Key Laboratory of Molecular Nuclear Medicine, Institute of Radiation Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin 300192, China; E-Mails: wudi521wan@163.com (D.W.); pharm8888@yahoo.com.cn (P.-X.L.); yuanmings1962@163.com (Y.-M.S.); zhangla43@yahoo.com.cn (L.-A.Z.); yi_she2005@yahoo.com.cn (Y.S.); qingfenliu@yahoo.com.cn (Q.-F.L.).

ABSTRACT
Gold nanoclusters have the tunable optical absorption property, and are promising for cancer cell imaging, photothermal therapy and radiotherapy. First-principle is a very powerful tool for design of novel materials. In the present work, structural properties, band gap engineering and tunable optical properties of Ag-doped gold clusters have been calculated using density functional theory. The electronic structure of a stable Au(20) cluster can be modulated by incorporating Ag, and the HOMO-LUMO gap of Au(20-) (n)Ag(n) clusters is modulated due to the incorporation of Ag electronic states in the HOMO and LUMO. Furthermore, the results of the imaginary part of the dielectric function indicate that the optical transition of gold clusters is concentration-dependent and the optical transition between HOMO and LUMO shifts to the low energy range as the Ag atom increases. These calculated results are helpful for the design of gold cluster-based biomaterials, and will be of interest in the fields of radiation medicine, biophysics and nanoscience.

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The outline of optical transition of Au20−nAgn clusters calculated by energy level.
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f5-ijms-12-02972: The outline of optical transition of Au20−nAgn clusters calculated by energy level.

Mentions: Figure 5 shows the transition energy level of Au20−nAgn from band structure calculations. The optical transition between HOMO-LUMO has been affected by Ag incorporation. The variation in energy level can be described in two stages. In the first stage of Au19Ag1 and Au18Ag2, Ag electronic states contribute to both HOMO and LUMO. Furthermore, LUMO has slightly shifted to the low energy range, which induces the decrease of transition level and can be responsible for the red-shifts of E2. In the second stage of Au17Ag3 and Au16Ag4, the increasing Ag atom induces more dispersive in d states, and LUMO has shifted to the high energy range, which may cause gap variation. It has been supposed that the gap widening of Au16Ag4 is important evidence for the enhancement of binding energy and structural stability [25]. The heavy doping can have obvious effects on electronic states, and further investigation is still interesting. More valuable information is still necessary to probe by optical absorption.


First-principles investigation of Ag-doped gold nanoclusters.

Zhang XD, Guo ML, Wu D, Liu PX, Sun YM, Zhang LA, She Y, Liu QF, Fan FY - Int J Mol Sci (2011)

The outline of optical transition of Au20−nAgn clusters calculated by energy level.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3116168&req=5

f5-ijms-12-02972: The outline of optical transition of Au20−nAgn clusters calculated by energy level.
Mentions: Figure 5 shows the transition energy level of Au20−nAgn from band structure calculations. The optical transition between HOMO-LUMO has been affected by Ag incorporation. The variation in energy level can be described in two stages. In the first stage of Au19Ag1 and Au18Ag2, Ag electronic states contribute to both HOMO and LUMO. Furthermore, LUMO has slightly shifted to the low energy range, which induces the decrease of transition level and can be responsible for the red-shifts of E2. In the second stage of Au17Ag3 and Au16Ag4, the increasing Ag atom induces more dispersive in d states, and LUMO has shifted to the high energy range, which may cause gap variation. It has been supposed that the gap widening of Au16Ag4 is important evidence for the enhancement of binding energy and structural stability [25]. The heavy doping can have obvious effects on electronic states, and further investigation is still interesting. More valuable information is still necessary to probe by optical absorption.

Bottom Line: The electronic structure of a stable Au(20) cluster can be modulated by incorporating Ag, and the HOMO-LUMO gap of Au(20-) (n)Ag(n) clusters is modulated due to the incorporation of Ag electronic states in the HOMO and LUMO.Furthermore, the results of the imaginary part of the dielectric function indicate that the optical transition of gold clusters is concentration-dependent and the optical transition between HOMO and LUMO shifts to the low energy range as the Ag atom increases.These calculated results are helpful for the design of gold cluster-based biomaterials, and will be of interest in the fields of radiation medicine, biophysics and nanoscience.

View Article: PubMed Central - PubMed

Affiliation: Tianjin Key Laboratory of Molecular Nuclear Medicine, Institute of Radiation Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin 300192, China; E-Mails: wudi521wan@163.com (D.W.); pharm8888@yahoo.com.cn (P.-X.L.); yuanmings1962@163.com (Y.-M.S.); zhangla43@yahoo.com.cn (L.-A.Z.); yi_she2005@yahoo.com.cn (Y.S.); qingfenliu@yahoo.com.cn (Q.-F.L.).

ABSTRACT
Gold nanoclusters have the tunable optical absorption property, and are promising for cancer cell imaging, photothermal therapy and radiotherapy. First-principle is a very powerful tool for design of novel materials. In the present work, structural properties, band gap engineering and tunable optical properties of Ag-doped gold clusters have been calculated using density functional theory. The electronic structure of a stable Au(20) cluster can be modulated by incorporating Ag, and the HOMO-LUMO gap of Au(20-) (n)Ag(n) clusters is modulated due to the incorporation of Ag electronic states in the HOMO and LUMO. Furthermore, the results of the imaginary part of the dielectric function indicate that the optical transition of gold clusters is concentration-dependent and the optical transition between HOMO and LUMO shifts to the low energy range as the Ag atom increases. These calculated results are helpful for the design of gold cluster-based biomaterials, and will be of interest in the fields of radiation medicine, biophysics and nanoscience.

Show MeSH
Related in: MedlinePlus