Janice Musfeldt

UTK chemistry

Imagine yourself inside a manganese-oxide crystal; surrounded by a tiny jungle-gym-like lattice, you see manganese and oxygen atoms bonded at regularly spaced intervals. The atoms vibrate and the molecule hums with electromagnetic energy—which not only holds the system together, but is also responsible for atomic structure, chemical reactions, the attractive and repulsive forces associated with electrical charge and magnetism, and all other electromagnetic phenomena.

Inside a three-dimensional material, the bonds reach in all directions, except, of course, at the edges.

But what if instead of three dimensions you confine the material to zero (a quantum dot), one (a straight line), or two dimensions (a plane)? Then, what happens to the charge and bonding, chemical reactivity, and magnetic structure?

These questions fascinate JDRD team leader Jan Musfeldt and LDRD companion-project leader Andrew Christianson. Both study the exotic physical properties of magnetic nanoparticles—especially how size and shape can be used to fine-tune desirable physical and chemical properties that are intimately tied to the electronic and magnetic structure.

When length-scales shrink to 30 nanometers or less, quantum confinement squeezes electrons into a space approaching the size of their wavelength, causing unusual (and even emergent) properties to occur.

"Quantum confinement offers the opportunity to tune chemical bonding in nanomaterials," Musfeldt says, "yielding properties that, some day, may find application in novel devices."

Her team is working with two model materials, manganese oxide (MnO) and molybdenum disulfide (MoS2), to quantify the effects of strain and curvature on the chemical bonding. Their results should have wide

JDRD Project: Investigating the physical properties of magnetic nanoparticles;
LDRD Project: Neutron scattering study of magnetic and spin dynamic behavior in amine-stabilized transition metal and transition metal oxide nanoparticles, Andrew Christianson.

future applicability, because each forms the chemical basis for a much wider class of materials, says Musfeldt.

Two refereed publications, two presentations at international meetings, and a research grant from the Department of Energy have come from this work so far.

The Musfeldt research group: Henok, Jessica, Luciana, Ozge, Tanea, Xiaoshan, and Charles. Charles, Luciana, Ozge, and Xiaoshan contributed to this JDRD project.

Main panel: optical conductivity of bulk and nanoscale MnO at room temperature. Insets: rock salt crystal structure and measured reflectance of the two materials. Optical conductivity is calculated from the latter.