Richard E. Smalley - US grants

With support from the Experimental Physical Chemistry Program and the Chemistry Instrumentation Program, Professor Smalley is continuing his investigations of the properties, photochemistry, and surface chemistry of small metallic cluster ions. His studies of carbon clusters are directly relevant to the understanding of carbon condensation and survival and soot formation under conditions ranging from flames to the interstellar medium. Studies of surface reactions on small metal clusters should stimulate (and provide a rigorous testing ground for) the development of first-principles theoretical approaches to the molecular level details of surface phenomena. The research on mass-selected cluster ions will include (1) optical spectroscopy of cold clusters using tandem time-of-flight mass spectrometry, (2) ultraviolet photoelectron spectroscopy of negative clusters, and (3) Fourier transform ion cyclotron resonance studies of the surface chemistry and photophysics of cluster ions trapped in a magnetic field.

A X-ray facility consisting of a rotating anode X-ray generator and two different diffraction systems on opposite sides of the generator will be acquired with the funds from the Academic Research Infrastructure Program. One diffraction unit will be a 4-circle diffractometer for accurate lattice parameter and structural determinations of thin films, single crystals, and powder samples. A second diffraction unit will involve an advanced 2-dimensional array detector for small angle X-ray scattering from biological and thin film samples. The facility will be employed to study: 1) the structure of lanthanide endohedral fulleneres and fullerene-encapsulated metal clusters, the study of low-dimensional mixed-valence compounds associated with superconduct-ivity and and charge density waves, 3) various properties of the unique van der Waals C60 solids, 4) magnetic multilayer thin films, 5) diamond thin films prepared by chemical vapor deposition and ion- implantation techniques, 6) growth of thin ferroelectric films on crystalline and amorphous substrates, 7) genetic features of regulatory proteins and the biochemistry and biology of repressor proteins, 8) the thermodynamic properties of natural minerals. A modern X-ray facility with two types of diffractometers will be employed to study a diverse range of materials by scientists in the Chemistry, Electrical Engineering, Biosciences, Materials Science and Geology Departments. The materials studied will include fullerenes, diamond thin films, repressor proteins, magnetic multilayers, ferroelectric thin films, and natural minerals.

9522251 Smalley This project addresses one of the grand challenges of nanotechnology: learning how to image and manipulate individual objects on the nanometer scale. Using carbon networks in the form of fullerene nanotubes and wires, this project aims to develop a new generation of probes which connect the macroscopic to the nanoscopic world with chemically specific, atomic precision. Whereas x-ray diffraction and related techniques have long been the basis of our detailed understanding of objects on this atomic length scale, they only work with large numbers of identical copies of the structure arranged in regular crystal lattices. Since the invention and early applications of scanning tunneling microscopy (STM) it has become increasingly clear that it is possible, at least in principle, to break loose from this requirement of needing a crystalline array. It should be possible to image, probe and manipulate individual structures, one by one, on the nanometer scale. Extensions of the idea of STM to other proximate probes such as atomic force microscopy (AFM), and magnetic force microscopy (MFM) have therefore become a major scientific endeavor worldwide. The common feature of all these methods is that they rely on a direct, physical connection between the macroscopic and nanoscopic realms in the form of a tiny "tip" which is scanned with sub-angstrom precision by piezoelectric devices. Most bulk materials are not chemically stable when elongated into probes of width less than 10 nanometers. However, carbon in the form of a graphine sheet is chemically stable in the form of fullerene balls and tubes even when these are less that 1 nm in diameter. This project is aimed at the general development of fullerne tubes as the tips of proximate probes and manipulators. Fullerene nanotubes will be produced both by currently known techniques using carbon arcs and/or catalytic particles and by new methods presently under development. These involve production o f single- and multi-walled nanotubes by laser vaporization of carbon/metal catalyst composite targets in a quartz tube furnace, and controlled growth of mounted "seed crystal" nanotubes in high electric fields. Mounting techniques will be developed to attach individual nanotubes to sharpened platinum electrodes with good electrical contact and reliable mechanical, chemical stability. Electrical and mechanical properties of the individually mounted nanotubes will be measured, including their ability to serve as efficient antennas at optical frequencies and their Q value when used as a nanoscopic cantilever. ***

1 9711785 Smalley The objective of this Selected Research Opportunity Grant is to interrogate the true tensile strength of an individual single-wall carbon nanotube (SWNT). Achieving these very difficult experiments will require substantial improvements in techniques for isolating, manipulating, and securing SWNT ropes onto fabricated supports. A single continuous rope of SWNTs will be draped cross metallic line features on a silicon wafer fabricated at the Stanford Nanofabrication Facility. The sample will then be introduced into an atomic force microscope which will be used for three purposes: (1) The entire sample will be scanned periodically, first to find an attractive span, and subsequently to look for signs of breakage and slippage; (2) High-resolution scans of the rope lying on the support lines on either side of the span will yield the geometry of the rope, giving a good estimate for the number of SWNTs in the rope; (3) The AFM tip will be engaged at one point in the middle of the span to deflect the rope. The known AFM cantilever force constant along with the measured deflections will provide the information required to obtain tensile strengths of the rope and of the individual tubes. %%% New evidence suggests that carbon nanotubes are the strongest materials known, potentially enabling unique applications in many areas critical to the U.S. economy. This research will involve direct measurements of the strength of nanotube ropes using micromanipulators. The results will provide the foundation for research and development of nanotube based superstrong materials and their applications

9802892
Smalley
This award provides partial support for the acquisition of equipment to provide Rice University researchers with a state-of-the-art ultrahigh vacuum, variable-temperature scanning tunneling/atomic force microscope instrument. This instrument will address the needs for nanoscale imaging, localized spectroscopy, and single molecule device fabrication and transport measurement capabilities for a cluster of faculty members in the Physics, Chemistry, and Electrical and Computer Engineering Departments. A primary focus for this instrument is the study of fullerene nanotubes in a range of scientific and technological contexts.

The system will allow the following research activities:

1) imaging and spectroscopy of fullerene nanotubes and other nanoparticles of interest,
2) assembly of single-molecule and nanoparticle-based device structures,
3) characterization of hybrid e-beam lithography/molecular self-assembly device fabrication methods,
4) fabrication, characterization, and imaging applications of fullerene STM tips: C60- adsorbed STM tips, and fullerene nanotube AFM/STM tips,
5) structural imaging and spectroscopic investigations of functionalized fullerene nanotubes and nanotube defects using C60-adsorbed STM tips,
6) temperature-dependent nanoscale imaging and analysis of the phase transitions and structural transformations in nanosized polymers.

This instrument will be the only ultrahigh vacuum or variable temperature STM/AFM instrument at Rice University. It will therefore provide significant new experimental capabilities, enhancing the ongoing programs of several research groups as well as providing a state-of-the-art nanoscale facility for junior faculty with growing research programs.
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The focus of this Focused Research Group proposal will develop the molecular science of fullerene nanotubes. These new materials have been hailed for their materials properties and the applications that these properties promise. The single greatest impediment to realizing this promise is the current poverty of chemical approaches for manipulating the tubes as individual molecules. Single-walled nanotubes (swnts) are truly molecular entities, owing to their high degree of structural perfection, but the molecular science of manipulating them in the sense that chemists manipulate other molecules is still quite embryonic. These manipulations include solubilization, covalent derivatization of tube ends and sides, sorting by length, electrical type, and diameter, assembly, cutting, and synthesis of tubes of specific helicity. These are the tasks that comprise the basis of nanotube manipulation, and are central technologies in the realization of the promise of swnt. One particular aim will be to develop a variety of strategies to solubilizing nanotubes in various solvents, including water, by supramolecular routes. Associations of swnts with other molecules will be designed - e.g., polymers or large macrocyclic compounds - both for solubilizing the tubes and for assembling them without making any covalent attachment to their sides, thus preserving fully their intrinsic materials properties. Sorting tubes by length, type, and diameter will be crucial to fulfilling hopes of using nanotubes as wires in molecular electronics. Crude separations by length and diameter have begun, but cleaner, scalable chromatographic and electrophoretic methods are needed. Sorting by electrical type will be approached by exploiting their different electrical and magnetic properties(e.g., using electrophoresis, electrochemistry, and electric or magnetic field gradients), as well as their structural differences to derivatize selectively by type.

A grand challenge is to synthesize tubes of a given electrical type. The plan is to utilize seed crystals of a particular type, (separated by methods developed as part of the proposed work), and use covalent chemistry at the end to assemble a catalyst for growth there. This challenge will make demands on several of the other goals, providing both a rich driving force, and, if successful, a remarkable new materials science with far-reaching technological impact.
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This Focused Research Group project will have a major impact in a fast-breaking area focused on the development of the molecular science of fullerene nanotubes. The research is highly synergistic, multidisciplinary, high-risk and high-impact, with a significant probability for technological payoff in areas that include molecular electronics and high performance composites. This team of intrnationally renown experts is being jointly supported by The Office of Mulitdisciplinary Affairs, The Division of Materials Research and The Chemistry Division of The Mathematical and Physical Sciences Directorate, and by the Division of Chemical and Transport Systems of The Engineering Directorate.

Stiil Valid

This grant supports the acquisition of a scanning electron spectroscopy for chemical analysis (ESCA) instrument for interface characterization of bio- , geo- and nanomaterials at Rice University. ESCA, also known as x-ray photoemission spectroscopy (XPS), is a powerful and versatile method for evaluating the surfaces of complex materials. The characterization of material interfaces is an important activity in much of materials research; for bio-, geo- and nanomaterials it is essential for developing new materials and understanding their properties. It is intrinsically a surface technique sensitive only to the top several angstroms of a sample, but with the appropriate conditions can be used to probe depths up to 20 nanometers. Several projects require depth profiling of atomic concentrations at surfaces while others need information about the nature of chemical bonding at interfaces. Still others are interested in chemical mapping of interfaces at the tens of micron level. Nearly all participants must be able to measure the atomic composition of surfaces, and the ability to analyze multiple samples quickly and consistently is of particular value. ESCA can measure the relative amounts of carbon and nitrogen at a surface and can determine whether the carbon is graphitic or bound to nitrogen. ESCA works by bombarding surfaces with a controlled X-ray source and resolving the kinetic energy of the photoemitted electrons; these energies are then used to identify surface atoms and their chemical state. Both the relative amounts of atomic species at surfaces, as well as their chemical environment can be deduced from XPS data. Though samples are evaluated under vacuum conditions, the technique is flexible- conductive and non-conductive powders and thin films have been analyzed with this method. The specific system has a focused, intense x-ray source, leading to small spot sizes (10 microns and high x-ray flux. This feature speeds data collection and its large sample platforms allow for rapid analysis of multiple samples. The scanning capability also enables a wider range of surface chemical experiments, such as depth profiles of atomic composition near surfaces and chemical mapping at the tens of micron length scale.

The acquisition of a scanning ESCA will be especially significant to student training and development, specialized courses for undergraduates and graduates, and workshops. Over thirty graduate students, and tens of post-docs and undergraduates will be able to use this system to understand how surface chemistry plays a role in their research. The existence of a scanning ESCA will allow us to implement a set of programs that not only teaches students how to use the instrument, but also highlights the importance of interface chemistry in areas such as bio- and nanoengineering.