April 14, 2022
David Nutt
cunews@cornell.edu
This image shows synthetic nanoparticles as they self-organize into filaments, then twist into cables, then bundle together into highly ordered bands, ultimately resulting in a thin film that is patterned at centimeter scales. Provided.
Nature may abhor a vacuum but it surely loves structure. Complex self-organized assemblies are found throughout the natural world, from double-helix DNA molecules to the photonic crystals that make butterfly wings so colorful and iridescent.
A Cornell-led project has created synthetic nanoclusters that can mimic this hierarchical self-assembly all the way from the nanometer to the centimeter scale, spanning seven orders of magnitude. The resulting synthetic thin films have the potential to serve as a model system for exploring biomimetic hierarchical systems and future advanced functions.
The group’s paper is published April 14 in Nature Materials. The lead author is postdoctoral researcher Haixiang Han of the Robinson Group.
Previously, the biggest hurdle for creating this type of synthetic nanomaterial has been the lack of nanoscale building blocks with the necessary versatility to interact across many length scales, enabling them to organize into complex structures, as found in biomolecules.
So a team led by co-senior authors Richard Robinson, associate professor of materials science and engineering in The Cornell College of Engineering and Tobias Hanrath, professor in the Smith School of Chemical and Biomolecular Engineering, turned to cadmium sulfide, a tried-and-true material for nanoparticle research.
Unlike previous efforts to synthesize the compound, the group performed a high-concentration version of synthesis that used very little solvent. The process produced “magic-size clusters” of 57 atoms, about 1.5 nanometers in length. Each of these nanoparticles had a shell of ligands – special binding molecules – that could interact with each other in such a way that they formed filaments several microns long and hundreds of nanometers wide. The filaments were “periodically decorated with these magic-size clusters, like a superhighway of cars, with perfect spacing between them,” according to Robinson.
“If you look down the front of the filament, down the center, it’s radially organized as well as hexagonally structured,” he said. “And because these structured filaments have attractive entanglements, it turns out that when they’re dried under the right conditions, they’ll self-assemble with long-range order.”
Remarkably, by carefully controlling the evaporative geometry, the filaments twisted into larger cables that are hundreds of microns long, and the cables then bundled together and aligned into highly ordered bands, ultimately resulting in a thin film that is patterned at centimeter scales.
“Usually you can’t synthesize something that has hierarchal organization from the nanometer through seven orders of magnitude larger. I think that’s really the special sauce,” Robinson said. “The assemblies mimic a lot of interesting natural products – natural mineralization, natural photonics – things that occur in nature that we haven’t been able to reproduce successfully in the lab.”
The mixture of organic and inorganic interactions gives the magic-size clusters the ability to create films with perfect periodic patterning. The fact that the thin film can show the whole spectrum of a rainbow, which the researchers demonstrated, is proof of its flawless structure.
“It’s likely that people haven’t seen this before because most syntheses have been done at low concentrations, so you have a lot of solvent. They don’t have the same ligand-ligand interactions,” he said. “We changed that. We moved the scale by one click of the decimal place, and we created this solventless synthesis.”
Among the most intriguing aspects of the nanomaterial film is that it displays chiral optical properties – the non-symmetric absorption of polarized light – which are likely manifest at the nanoparticle level, and this characteristic is amplified all the way up to the macroscopic scale. The thin films also share some surprising similarities with liquid crystals.
To better understand the behavior of the self-organization, Robinson and Hanrath consulted a group of collaborators.
Lena Kourkoutis, associate professor in applied and engineering physics, handled the electron microscopy that allowed the team to see where the nanoparticles were located within the filaments. Julia Dshemuchadse, assistant professor in materials science and engineering, theorized the rules that govern the filaments assembly and stability. Researchers from The University of Toronto and The Rochester Institute of Technology estimated the interactions between the electric dipoles that orient the clusters, and developed a theoretical model that showed why the evaporation method caused the nanoclusters to form such a perfectly periodic film, respectively.
The discovery of the remarkable multi-scale structures opens up new avenues to develop technologies that leverage their emerging chiroptical properties.
“The unique light-matter interactions of these chiroptical metamaterials can be used for a range of potential applications, from sensing, catalysis and circular polarized light-detectors to further-out prospects in spintronics, quantum computing and holography,” said Hanrath.
Co-authors include master’s student Shantanu Kallakuri, and doctoral students Yuan Yao and Rachael Skye; Curtis Williamson, Ph.D. ’19 and Douglas Nevers, Ph.D. ’18 of the Hanrath Energy Lab; Benjamin Savitzky, Ph.D. ’18; postdoctoral researcher Mengyu Xu; Oleksandr Voznyy from University of Toronto; Steven Weinstein from Rochester Institute of Technology.
The research was supported by the National Science Foundation. The researchers made use of the Cornell Center for Materials Research, which is supported by the NSF’s MRSEC program.
See the full article here .
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Once called “the first American university” by educational historian Frederick Rudolph, Cornell University represents a distinctive mix of eminent scholarship and democratic ideals. Adding practical subjects to the classics and admitting qualified students regardless of nationality, race, social circumstance, gender, or religion was quite a departure when Cornell was founded in 1865.
Today’s Cornell reflects this heritage of egalitarian excellence. It is home to the nation’s first colleges devoted to hotel administration, industrial and labor relations, and veterinary medicine. Both a private university and the land-grant institution of New York State, Cornell University is the most educationally diverse member of the Ivy League.
On the Ithaca campus alone nearly 20,000 students representing every state and 120 countries choose from among 4,000 courses in 11 undergraduate, graduate, and professional schools. Many undergraduates participate in a wide range of interdisciplinary programs, play meaningful roles in original research, and study in Cornell programs in Washington, New York City, and the world over.
Cornell University is a private, statutory, Ivy League and land-grant research university in Ithaca, New York. Founded in 1865 by Ezra Cornell and Andrew Dickson White, the university was intended to teach and make contributions in all fields of knowledge—from the classics to the sciences, and from the theoretical to the applied. These ideals, unconventional for the time, are captured in Cornell’s founding principle, a popular 1868 quotation from founder Ezra Cornell: “I would found an institution where any person can find instruction in any study.”
The university is broadly organized into seven undergraduate colleges and seven graduate divisions at its main Ithaca campus, with each college and division defining its specific admission standards and academic programs in near autonomy. The university also administers two satellite medical campuses, one in New York City and one in Education City, Qatar, and Jacobs Technion-Cornell Institute in New York City, a graduate program that incorporates technology, business, and creative thinking. The program moved from Google’s Chelsea Building in New York City to its permanent campus on Roosevelt Island in September 2017.
Cornell is one of the few private land grant universities in the United States. Of its seven undergraduate colleges, three are state-supported statutory or contract colleges through the SUNY – The State University of New York system, including its Agricultural and Human Ecology colleges as well as its Industrial Labor Relations school. Of Cornell’s graduate schools, only the veterinary college is state-supported. As a land grant college, Cornell operates a cooperative extension outreach program in every county of New York and receives annual funding from the State of New York for certain educational missions. The Cornell University Ithaca Campus comprises 745 acres, but is much larger when the Cornell Botanic Gardens (more than 4,300 acres) and the numerous university-owned lands in New York City are considered.
Alumni and affiliates of Cornell have reached many notable and influential positions in politics, media, and science. As of January 2021, 61 Nobel laureates, four Turing Award winners and one Fields Medalist have been affiliated with Cornell. Cornell counts more than 250,000 living alumni, and its former and present faculty and alumni include 34 Marshall Scholars, 33 Rhodes Scholars, 29 Truman Scholars, 7 Gates Scholars, 55 Olympic Medalists, 10 current Fortune 500 CEOs, and 35 billionaire alumni. Since its founding, Cornell has been a co-educational, non-sectarian institution where admission has not been restricted by religion or race. The student body consists of more than 15,000 undergraduate and 9,000 graduate students from all 50 American states and 119 countries.
History
Cornell University was founded on April 27, 1865; the New York State (NYS) Senate authorized the university as the state’s land grant institution. Senator Ezra Cornell offered his farm in Ithaca, New York, as a site and $500,000 of his personal fortune as an initial endowment. Fellow senator and educator Andrew Dickson White agreed to be the first president. During the next three years, White oversaw the construction of the first two buildings and traveled to attract students and faculty. The university was inaugurated on October 7, 1868, and 412 men were enrolled the next day.
Cornell developed as a technologically innovative institution, applying its research to its own campus and to outreach efforts. For example, in 1883 it was one of the first university campuses to use electricity from a water-powered dynamo to light the grounds. Since 1894, Cornell has included colleges that are state funded and fulfill statutory requirements; it has also administered research and extension activities that have been jointly funded by state and federal matching programs.
Cornell has had active alumni since its earliest classes. It was one of the first universities to include alumni-elected representatives on its Board of Trustees. Cornell was also among the Ivies that had heightened student activism during the 1960s related to cultural issues; civil rights; and opposition to the Vietnam War, with protests and occupations resulting in the resignation of Cornell’s president and the restructuring of university governance. Today the university has more than 4,000 courses. Cornell is also known for the Residential Club Fire of 1967, a fire in the Residential Club building that killed eight students and one professor.
Since 2000, Cornell has been expanding its international programs. In 2004, the university opened the Weill Cornell Medical College in Qatar. It has partnerships with institutions in India, Singapore, and the People’s Republic of China. Former president Jeffrey S. Lehman described the university, with its high international profile, a “transnational university”. On March 9, 2004, Cornell and Stanford University laid the cornerstone for a new ‘Bridging the Rift Center’ to be built and jointly operated for education on the Israel–Jordan border.
Research
Cornell, a research university, is ranked fourth in the world in producing the largest number of graduates who go on to pursue PhDs in engineering or the natural sciences at American institutions, and fifth in the world in producing graduates who pursue PhDs at American institutions in any field. Research is a central element of the university’s mission; in 2009 Cornell spent $671 million on science and engineering research and development, the 16th highest in the United States. Cornell is classified among “R1: Doctoral Universities – Very high research activity”.
For the 2016–17 fiscal year, the university spent $984.5 million on research. Federal sources constitute the largest source of research funding, with total federal investment of $438.2 million. The agencies contributing the largest share of that investment are The Department of Health and Human Services and the National Science Foundation, accounting for 49.6% and 24.4% of all federal investment, respectively. Cornell was on the top-ten list of U.S. universities receiving the most patents in 2003, and was one of the nation’s top five institutions in forming start-up companies. In 2004–05, Cornell received 200 invention disclosures; filed 203 U.S. patent applications; completed 77 commercial license agreements; and distributed royalties of more than $4.1 million to Cornell units and inventors.
Since 1962, Cornell has been involved in unmanned missions to Mars. In the 21st century, Cornell had a hand in the Mars Exploration Rover Mission. Cornell’s Steve Squyres, Principal Investigator for the Athena Science Payload, led the selection of the landing zones and requested data collection features for the Spirit and Opportunity rovers. NASA-JPL/Caltech engineers took those requests and designed the rovers to meet them. The rovers, both of which have operated long past their original life expectancies, are responsible for the discoveries that were awarded 2004 Breakthrough of the Year honors by Science. Control of the Mars rovers has shifted between National Aeronautics and Space Administration’s JPL-Caltech and Cornell’s Space Sciences Building.
Further, Cornell researchers discovered the rings around the planet Uranus, and Cornell built and operated the telescope at Arecibo Observatory located in Arecibo, Puerto Rico until 2011, when they transferred the operations to SRI International, the Universities Space Research Association and the Metropolitan University of Puerto Rico [Universidad Metropolitana de Puerto Rico].
The Automotive Crash Injury Research Project was begun in 1952. It pioneered the use of crash testing, originally using corpses rather than dummies. The project discovered that improved door locks; energy-absorbing steering wheels; padded dashboards; and seat belts could prevent an extraordinary percentage of injuries.
In the early 1980s, Cornell deployed the first IBM 3090-400VF and coupled two IBM 3090-600E systems to investigate coarse-grained parallel computing. In 1984, the National Science Foundation began work on establishing five new supercomputer centers, including the Cornell Center for Advanced Computing, to provide high-speed computing resources for research within the United States. As a National Science Foundation center, Cornell deployed the first IBM Scalable Parallel supercomputer.
In the 1990s, Cornell developed scheduling software and deployed the first supercomputer built by Dell. Most recently, Cornell deployed Red Cloud, one of the first cloud computing services designed specifically for research. Today, the center is a partner on the National Science Foundation XSEDE-Extreme Science Engineering Discovery Environment supercomputing program, providing coordination for XSEDE architecture and design, systems reliability testing, and online training using the Cornell Virtual Workshop learning platform.
Cornell scientists have researched the fundamental particles of nature for more than 70 years. Cornell physicists, such as Hans Bethe, contributed not only to the foundations of nuclear physics but also participated in the Manhattan Project. In the 1930s, Cornell built the second cyclotron in the United States. In the 1950s, Cornell physicists became the first to study synchrotron radiation.
During the 1990s, the Cornell Electron Storage Ring, located beneath Alumni Field, was the world’s highest-luminosity electron-positron collider. After building the synchrotron at Cornell, Robert R. Wilson took a leave of absence to become the founding director of DOE’s Fermi National Accelerator Laboratory, which involved designing and building the largest accelerator in the United States.
Cornell’s accelerator and high-energy physics groups are involved in the design of the proposed ILC-International Linear Collider(JP) and plan to participate in its construction and operation. The International Linear Collider(JP), to be completed in the late 2010s, will complement the CERN Large Hadron Collider(CH) and shed light on questions such as the identity of dark matter and the existence of extra dimensions.
As part of its research work, Cornell has established several research collaborations with universities around the globe. For example, a partnership with the University of Sussex(UK) (including the Institute of Development Studies at Sussex) allows research and teaching collaboration between the two institutions.
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