國立高雄大學圖資館 |

Language: English

Back

Structural investigations of surface...

Aruguete, Deborah Michiko.

Structural investigations of surfaces and orientation-specific phenomena in nanocrystals and their assemblies.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Structural investigations of surfaces and orientation-specific phenomena in nanocrystals and their assemblies.
Author:	Aruguete, Deborah Michiko.
Description:	158 p.
Notes:	Adviser: A. Paul Alivisatos.
Notes:	Source: Dissertation Abstracts International, Volume: 67-08, Section: B, page: 4435.
Contained By:	Dissertation Abstracts International67-08B.
Subject:	Engineering, Materials Science.
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3228258
ISBN:	9780542822179

Structural investigations of surfaces and orientation-specific phenomena in nanocrystals and their assemblies.
Aruguete, Deborah Michiko.

Structural investigations of surfaces and orientation-specific phenomena in nanocrystals and their assemblies. - 158 p.

Adviser: A. Paul Alivisatos.

Thesis (Ph.D.)--University of California, Berkeley, 2006.

Crystallographically-aligned assemblies of colloidal CdSe nanorods are examined with linearly-polarized Se-EXAFS spectroscopy, which probes bonding along different directions in the nanorod. This orientation-specific probe is used, because it is expected that the presence of specific surfaces in a nanorod might cause bond relaxations specific to different crystallographic directions. Se-Se distances are found to be contracted along the long axis of the nanorod, while Cd-Se distances display no angular dependence, which is different from the bulk. Ab-initio density functional theory calculations upon CdSe nanowires indicate that relaxations on the rod surfaces cause these changes.

ISBN: 9780542822179Subjects--Topical Terms:

226940
Engineering, Materials Science.

Structural investigations of surfaces and orientation-specific phenomena in nanocrystals and their assemblies.
LDR:03565nmm _2200301 _450 001 180640
005 20080111103803.5
008 090528s2006 eng d
020 $a 9780542822179
035 $a 00311665
040 $a UMI $c UMI
100 0 $a Aruguete, Deborah Michiko. $3 264217
245 1 0 $a Structural investigations of surfaces and orientation-specific phenomena in nanocrystals and their assemblies.
300 $a 158 p.
500 $a Adviser: A. Paul Alivisatos.
500 $a Source: Dissertation Abstracts International, Volume: 67-08, Section: B, page: 4435.
502 $a Thesis (Ph.D.)--University of California, Berkeley, 2006.
520 # $a Crystallographically-aligned assemblies of colloidal CdSe nanorods are examined with linearly-polarized Se-EXAFS spectroscopy, which probes bonding along different directions in the nanorod. This orientation-specific probe is used, because it is expected that the presence of specific surfaces in a nanorod might cause bond relaxations specific to different crystallographic directions. Se-Se distances are found to be contracted along the long axis of the nanorod, while Cd-Se distances display no angular dependence, which is different from the bulk. Ab-initio density functional theory calculations upon CdSe nanowires indicate that relaxations on the rod surfaces cause these changes.
520 # $a Ordered self-assembled aggregates of cobalt nanocrystals are examined with transmission electron microscopy(TEM) and selected-area electron diffraction (SAED). SAED patterns from multilayered assemblies show that the nanocrystals have preferred crystallographic orientations. It is proposed that the nanocrystals are organized in a vortex-like or "loop-closing" arrangement, possibly due to magnetism. SAED and dark field imaging used to investigate this hypothesis are presented, along with the data analysis. The effects of magnetism and nanocrystal faceting are discussed.
520 # $a Studies of colloidal nanocrystals and their assemblies are presented. Two of these studies concern the atomic-level structural characterization of the surfaces, interfaces, and interiors present in II-VI semiconductor nanorods. The third study investigates the crystallographic arrangement of cobalt nanocrystals in self-assembled aggregates.
520 # $a ZnS/CdS-CdSe core-shell nanorods are studied with Se, Zn, Cd, and S X-ray absorption spectroscopy (XAS). It is hypothesized that there are two major factors influencing the core and shell structures of the nanorods: the large surface area-to-volume ratio, and epitaxial strain. The presence of the surface may induce bond rearrangements or relaxations to minimize surface energy, epitaxial strain might cause the core and shell lattices to contract or expand to minimize strain energy. A marked contraction of Zn-S bonds is observed in the core-shell nanorods, indicating that surface relaxations may dominate the structure of the nanorod (strain might otherwise drive the Zn-S lattice to accommodate the larger US or CdSe lattices via bond expansion). EXAFS and X-ray diffraction (XRD) indicate that Cd-Se bond relaxations might be anisotropic, an expected phenomenon for a rod-shaped nanocrystal.
590 $a School code: 0028.
650 # 0 $a Engineering, Materials Science. $3 226940
650 # 0 $a Chemistry, Physical. $3 226924
690 $a 0494
690 $a 0794
710 0 # $a University of California, Berkeley. $3 212474
773 0 # $g 67-08B. $t Dissertation Abstracts International
790 $a 0028
790 1 0 $a Alivisatos, A. Paul, $e advisor
791 $a Ph.D.
792 $a 2006
856 4 0 $u http://libsw.nuk.edu.tw:81/login?url=http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3228258 $z http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3228258