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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 imaginary part of dielectric function ɛ2(ω) of Au20 clusters.
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f3-ijms-12-02972: The imaginary part of dielectric function ɛ2(ω) of Au20 clusters.

Mentions: For investigating the optical transition of Au20−nAgn clusters, it is necessary to investigate the imaginary part of the dielectric function, because it is very important to the optical properties of any materials. Regarding Au20 in Figure.3, there are two main peaks in ɛ2(ω), at 1.79 and 2.51 eV, respectively (namely E1, E2), which are very close to the previous results of 1.86 and 2.78 [21]. It can be seen in the inset of Figure 3 that direct transition can be caused between HOMO and LUMO. Therefore, it can be expected that E1 (1.79 eV) should mainly be caused by optical transitions between Au 6s 55% (and Au d, 45%) states in HOMO and Au 6s states in LUMO, which are close to the other first-principles evaluation (1.86 eV) [21]. Moreover, it is not far from the HOMO-LUMO gap of 1.48 eV. In the DOS of Au20, the Au d states produce two peaks, 1.41 and 1.97 eV, which can induce some electronic states in the energy level range of −4∼0 eV. Thus, the optical transitions of E2 can be due to the optical transitions between HOMO-1 consist of Au d states and LUMO consist of Au 6s (and Au p) states.


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 imaginary part of dielectric function ɛ2(ω) of Au20 clusters.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f3-ijms-12-02972: The imaginary part of dielectric function ɛ2(ω) of Au20 clusters.
Mentions: For investigating the optical transition of Au20−nAgn clusters, it is necessary to investigate the imaginary part of the dielectric function, because it is very important to the optical properties of any materials. Regarding Au20 in Figure.3, there are two main peaks in ɛ2(ω), at 1.79 and 2.51 eV, respectively (namely E1, E2), which are very close to the previous results of 1.86 and 2.78 [21]. It can be seen in the inset of Figure 3 that direct transition can be caused between HOMO and LUMO. Therefore, it can be expected that E1 (1.79 eV) should mainly be caused by optical transitions between Au 6s 55% (and Au d, 45%) states in HOMO and Au 6s states in LUMO, which are close to the other first-principles evaluation (1.86 eV) [21]. Moreover, it is not far from the HOMO-LUMO gap of 1.48 eV. In the DOS of Au20, the Au d states produce two peaks, 1.41 and 1.97 eV, which can induce some electronic states in the energy level range of −4∼0 eV. Thus, the optical transitions of E2 can be due to the optical transitions between HOMO-1 consist of Au d states and LUMO consist of Au 6s (and Au p) states.

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