McNeese faculty Dr. Anil K. Kandalam, left, assistant professor of physics, and Dr. Kiran Boggavarapu, assistant professor of chemistry, display a ball and stick model of a lead sulfide baby crystal. These professors recently collaborated with research colleagues at Johns Hopkins University to discover baby crystals-the smallest possible stable cluster that resembles its bulk-structure and can be replicated to form solid material. McNeese Photo
McNeese State University faculty Dr. Kiran Boggavarapu, assistant professor of chemistry, and Dr. Anil K. Kandalam, assistant professor of physics, have once again collaborated with research colleagues from Johns Hopkins University in Maryland to discover something new - lead sulfide (PbS) baby crystals.
Baby crystal is the smallest possible stable cluster that resembles its bulk-structure and can be replicated to form solid material. Baby crystals and their assembly into nanoblocks could help provide a better understanding of the mechanisms involved in the formation of solids, according to a paper about the discovery, "(PbS)32: A Baby Crystal," published in a January issue of the Journal of Chemical Physics.
The theoretical investigations were conducted at McNeese, while the experimental work was conducted at Johns Hopkins.
At McNeese, Boggavarapu and Kandalam identified the baby crystal by running computer simulations that calculated the energy and geometry of different structures containing different numbers of atoms. They found that (PbS)32 is the smallest stable unit that possesses both the same cubic structure and coordination number as the bulk crystal.
The McNeese pair then asked their colleagues to experimentally test their theoretical findings. "To do this, our experimental collaborators at Johns Hopkins gently deposited the (PbS)32 clusters on a graphite surface where these clusters could easily migrate and merge together to form larger nanoblocks," said Boggavarapu.
"By using scanning tunneling microscope images to measure the dimensions of the resultant lead sulfide nanoblocks, they confirmed that the (PbS)32 baby crystals had indeed stacked together as we theoretically predicted," explained Kandalam.
According to Boggavarapu, their computations have provided a rubric for understanding the mechanism involved in the formation of nanoblocks on a surface as well as the formation of lead sulfide solids.
In addition, Kandalam said the lead sulfide material studied for the baby crystal formation has several potential applications in semiconducting and optoelectronic devices.
Both professors have been recently involved in other scientific discoveries. Last fall, both Kandalam and Boggavarapu collaborated with researchers from Virginia Commonwealth University and Johns Hopkins on the discovery of "magnetic superhalogens," a new class of superhalogens, while Kandalam worked with researchers from Virginia Commonwealth and the University of Konstanz in Germany in to discover a new class of highly electronegative chemical species called hyperhalogens.
Drs. Kandalam and Boggavarapu were assisted on the baby crystal project by McNeese students, Rameshu Rallabandi, a chemistry graduate student, and Pratik Koirala, a physics senior.