6.10.24
Rachel Harrison
rachel.harrison@nyu.edu
(212) 998-6797
Developing transparent particles and imaging their positions, researchers shed light on never-before-seen interiors of crystalline structures.
The new technique allows scientists to see each particle that makes up colloidal crystals and to create dynamic three-dimensional models. Credit: Shihao Zang
A team of New York University researchers has created a new way to visualize crystals by peering inside their structures, akin to having X-ray vision. Their new technique—which they aptly named “Crystal Clear”—combines the use of transparent particles and microscopes with lasers that allow scientists to see each unit that makes up the crystal and to create dynamic three-dimensional models.
“This is a powerful platform for studying crystals,” says Stefano Sacanna, professor of chemistry at NYU and the principal investigator for the study, published in the journal Nature Materials. “Previously, if you looked at a colloidal crystal through a microscope, you could only get a sense of its shape and structure of the surface. But we can now see inside and know the position of every unit in the structure.”
Atomic crystals are solid materials whose building blocks are positioned in a repeating, orderly fashion. Every now and then, an atom is missing or out of place, resulting in a defect. The arrangement of atoms and defects is what creates different crystalline materials—from table salt to diamonds—and gives them their properties.
To study crystals, many scientists, including Sacanna, look to crystals composed of miniscule spheres called colloidal particles rather than atoms. Colloidal particles are tiny—often around a micrometer in diameter, or dozens of times smaller than a human hair—but are much larger than atoms and therefore easier to see under a microscope.
A see-through structure
In their ongoing work to understand how colloidal crystals form, the researchers recognized the need to see inside these structures. Led by Shihao Zang, a PhD student in Sacanna’s lab and the study’s first author, the team set out to create a method to visualize the building blocks inside a crystal. They first developed colloidal particles that were transparent and added dye molecules to label them, making each particle possible to distinguish under a microscope using their fluorescence.
A microscope alone wouldn’t allow the researchers to see inside a crystal, so they turned to an imaging technique called confocal microscopy, which uses a laser beam that scans through material to produce targeted fluorescence from the dye molecules. This reveals each two-dimensional plane of a crystal, which can be stacked on top of each other to build a three-dimensional digital model and identify the location of each particle. The models can be rotated, sliced, and taken apart to look inside the crystals and see any defects.
Identifying coordinates of crystal particles from 3D scans.
In one set of experiments, the researchers used this imaging method on crystals that form when two of the same type of crystals grow together—a phenomenon known as “twinning.” When they looked inside models of crystals having structures equivalent to table salt or an alloy of copper and gold, they could see the shared plane of the adjoined crystals, a defect that gives rise to these particular shapes. This shared plane revealed the molecular origin of twinning.
A 3D scan and digital model of crystal “twinning” reveals a shared plane of the adjoining crystals, which gives rise to their shape. Credit: Shihao Zang
Crystals in motion
In addition to looking at static crystals, this new technique allows scientists to visualize crystals as they change. For example, what happens when crystals melt—do particles rearrange, and do defects move? In an experiment in which the researchers melted a crystal with the structure of the mineral salt cesium chloride, they were surprised to find that the defects were stable and did not move around as expected.
3D reconstruction identifies internal defects in crystals.
In order to validate their experiments on static and dynamic crystals, the team also used computer simulations to create crystals with the same characteristics, confirming that their “Crystal Clear” method accurately captured what is inside crystals.
“In a sense, we’re trying to put our own simulations out of business with this experiment—if you can see inside the crystal, you may not need simulations anymore,” jokes Glen Hocky, assistant professor of chemistry at NYU, a faculty member in the Simons Center for Computational Physical Chemistry at NYU, and the study’s co-corresponding author.
Now that scientists have a method for visualizing the inside of crystals, they can more easily study their chemical history and how they form, which could pave the way for building better crystals and developing photonic materials that interact with light.
“Being able to see inside crystals gives us greater insight into how the crystallization process works and can perhaps help us to optimize the process of growing crystals by design,” adds Sacanna.
Additional study authors include Adam Hauser and Sanjib Paul of NYU. The research was supported by the US Army Research Office (award number W911NF-21-1-0011), with additional support from the National Institute of Health (R35GM138312), and used NYU IT High Performance Computing resources, including those supported by the Simons Center for Computational Physical Chemistry at NYU (grant number 839534).
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More than 175 years ago, Albert Gallatin, the distinguished statesman who served as secretary of the treasury under Presidents Thomas Jefferson and James Madison, declared his intention to establish “in this immense and fast-growing city … a system of rational and practical education fitting for all and graciously opened to all.” Founded in 1831, New York University is now one of the largest private universities in the United States. Of the more than 3,000 colleges and universities in America, New York University is one of only 71 member institutions of the distinguished Association of American Universities.
New York University is a private research university in New York City. Chartered in 1831 by the New York State Legislature, NYU was founded by a group of New Yorkers led by then Secretary of the Treasury Albert Gallatin.
In 1832, the initial non-denominational all-male institution began its first classes near City Hall based on a curriculum focused on a secular education. The university, in 1833, then moved and has maintained its main campus in Greenwich Village surrounding Washington Square Park. Since then, the university has added an engineering school in Brooklyn’s MetroTech Center and graduate schools throughout Manhattan. New York University has become the largest private university in the United States by enrollment, with a total of over 55,000 enrolled students, including over 26,000 undergraduate students and 29,000 graduate students. New York University also receives the most applications of any private institution in the United States and admissions is considered highly selective.
New York University is organized into 10 undergraduate schools, including the College of Arts & Science, Gallatin School, Steinhart School, Stern School of Business, Tandon School of Engineering, and the Tisch School of Arts. New York University’s 15 graduate schools include the Grossman School of Medicine, School of Law, Wagner Graduate School of Public Service, School of Professional Studies, School of Social Work, Rory Meyers School of Nursing, and Silver School of Social Work. The university’s internal academic centers include the Courant Institute of Mathematical Sciences, Center for Data Science, Center for Neural Science, Clive Davis Institute, Institute for the Study of the Ancient World, Institute of Fine Arts, and the New York University Langone Health System. New York University is a global university with degree-granting campuses at New York University Abu Dhabi and New York University Shanghai, and academic centers in Accra, Berlin, Buenos Aires, Florence, London, Los Angeles, Madrid, Paris, Prague, Sydney, Tel Aviv, and Washington, D.C.
Past and present faculty and alumni include Nobel Laureates, Turing Award winners, Fields Medalists, MacArthur Fellows, Pulitzer Prize winners, heads of state, U.S. Supreme Court justices, U.S. governors, mayors of New York City, U.S. Senators, members of the U.S. House of Representatives, Federal Reserve Chairmen, Academy Award winners, Emmy Award winners,Tony Award winners, Grammy Award winners, billionaires, and Olympic medalists. The university has also produced Rhodes Scholars, Marshall Scholars, Schwarzman Scholars, and Mitchell Scholars.
Research
New York University is classified among “R1: Doctoral Universities – Very high research activity” and annual research expenditures total over $1 billion. The university was the founding institution of the American Chemical Society. The New York University Grossman School of Medicine has received over $300 million in external research funding from the National Institutes of Health. New York University has been granted many patents, very high in the world. New York University owns the fastest supercomputer in New York City.
“Greene,” NYU’s new high-performance computing cluster, is one of the top 100 Greenest Supercomputers in the World. In an educational environment where cutting-edge research involves increasingly staggering amounts of data, Greene, which balances the need for next-level computation and storage capacity with the need to reduce reliance on fossil-fuel consumption. The new high performance computing (HPC) cluster will bolster research across a wide range of disciplines, from biomolecular genetics to the political ramifications of social media behavior to artificial intelligence. The new Greene supercomputer, built by Lenovo, has the capability to do four quadrillion (4 x 1015) calculations per second, making it 10 times faster than both NYU’s current supercomputer and the most powerful computer in the New York area. Greene connects to NYU research facilities with the fastest network available in any institute of higher education in the United States.
As of 2016, New York University hardware researchers and their collaborators enjoy the largest outside funding level for hardware security of any institution in the United States, including grants from the National Science Foundation, the Office of Naval Research, the Defense Advanced Research Projects Agency, the United States Army Research Laboratory, the Air Force Research Laboratory, the Semiconductor Research Corporation, and companies including Twitter, Boeing, Microsoft, and Google.
Four New York University Arts & Science departments have ranked very highly in the Shanghai Academic Rankings of World Universities by Academic Subjects (Economics, Politics, Psychology, and Sociology).
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