Award Abstract #0102960
NER: Exploration of Phase Transformations at nm-length Scale

NSF Org:	DMR Division of Materials Research
Initial Amendment Date:	June 11, 2001
Latest Amendment Date:	June 11, 2001
Award Number:	0102960
Award Instrument:	Standard Grant
Program Manager:	H. Hollis Wickman DMR Division of Materials Research MPS Directorate for Mathematical & Physical Sciences
Start Date:	July 1, 2001
Expires:	June 30, 2003 (Estimated)
Awarded Amount to Date:	$100000
Investigator(s):	Dragomir Davidovic dragomir.davidovic@physics.gatech.edu (Principal Investigator)
Sponsor:	GA Tech Research Corporation - GA Institute of Technology Office of Sponsored Programs Atlanta, GA 30332 404/894-4819
NSF Program(s):	DMR SHORT TERM SUPPORT, INTERFAC PROCESSES & THERMODYN
Field Application(s):	0106000 Materials Research
Program Reference Code(s):	AMPP, 9161, 1676
Program Element Code(s):	1712, 1414

ABSTRACT

This Nanoscale Exploratory Research (NER) project investigates liquid-to-solid and vapor-to-solid transformations in nanometer scale clusters. In nanometer-scale systems, phase transformations exhibit irregular variations of characteristic parameters and magic numbers. Other systems exhibiting such behavior are atomic nuclei, atoms, quantum dots, cluster beams and metallic nanowires. The proposed studies are important in understanding the role of clusters in biological systems, including identifying clusters that actuate electron transport pathways in biomolecular systems, and the adaptation of clusters as they connect to external objects, such as leads, DNA and proteins. A series of electrical transport measurements as a function of pressure and temperature are proposed to understand the electronic properties of these clusters. Nanoelectrodes with atomic scale gaps are immersed into a medium that is tuned sufficiently close to a bulk phase transformation. Then, by applying electric fields strongly localized in space, a cluster of different phase is nucleated locally between the electrodes. Electron transport investigates the electronic properties and stability of the cluster. Graduate and undergraduate students participating in the project receive training in nanofabrication technology, including visits to national nanofabrication facility, combined with fundamental experimental techniques in the laboratory. This experience makes them competitive for a range of careers in academia, industry and government.

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This Nanoscale Exploratory Research (NER) project investigates liquid-to-solid and vapor-to-solid transformations in nanometer scale objects. When the size of the objects approaches one nanometer, the transformations are significantly modified, and they acquire properties that are typically found in atoms and nuclei. Consequently, the objects of study are referred to with a new name: clusters. The properties of clusters as a function of size vary irregularly, in analogy with the periodic variation inside the periodic table of elements in atomic physics. Additionally, there are clusters that have very high stability. These are known as magic-number configurations, and are analogous to inert atoms. These clusters also occur naturally in biological systems, and they play important role on electronic transfer and binding to bio-molecules such as DNA and proteins. This project breaks new ground in combining nanotechnology on silicon-chip and electron transport through individual clusters, to determine their electronic and other properties, such as how clusters conduct electricity. The students involved in the project are thoroughly trained in cutting edge technologies important in further miniaturization of electronics. Additionally, they acquire basic laboratory skills, and specialized skills in high-level measurements. This experience will allow them to pursue careers in academia, industry and government.

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