Zachary M. Sherman, Delia J. Milliron, Thomas M. Truskett

ACS Nano 2024, XX, XXXX-XXXX

Each nanoparticle in a disordered material preferentially resonates (i.e. absorbs strongly) at a different frequency/wavelength of light. The distribution of these individual resonances completely determines the optical response of the collective ensemble.

Zachary M. Sherman*, Jiho Kang*, Delia J. Milliron, Thomas M. Truskett

*equal contribution

J. Chem. Phys. Lett. 2024, 15, 6424-6434

In this Perspective Review, we explain how integrated experiments and computational modeling have lead to fundamental insight into the optical properties of a variety of disordered metallic and doped semiconductor nanoparticle materials. 

Allison M. Green, Woo Je Chang, Zachary M. Sherman, Zarko Sakotic, Kihoon Kim, Daniel Wasserman, Delia J. Milliron, Thomas M. Truskett

ACS Photonics 2023, 11, 1280-1292

Most nanoparticle superlattices contain defects (e.g. grain boundaries and vacancies) when self-assembled. Here, we examine how these defects affect the far-field and near-field optical response of plasmonic superlattices. 

Jiho Kang*, Zachary M. Sherman*, Diana L. Conrad, Hannah S. N. Crory, Manuel N. Dominguez, Stephanie A. Valenzuela, Eric V. Anslyn, Thomas M. Truskett, Delia J. Milliron

*equal contribution

ACS Nano 2023, 17, 24218-24226

For colloidal gels self-assembled by molecularly linking tin-doped indium oxide (ITO) nanocrystals, we can synthetically tune the nanocrystal size, the surface ligand length, and the amount of tin doping. The effects of all of these control knobs on the optical response of colloidal gels can be described by a simple, analytic, "plasmon ruler" equation.

Kihoon Kim, Zachary M. Sherman, Angela Cleri, Woo Je Chang, Jon-Paul Maria, Thomas M. Truskett, Delia J. Milliron

Nano Lett. 2023, 23, 7633-7641

"Doping" in nanoparticle superlattices is controlled at two levels: at the atomic level, a fraction of indium sites in an indium oxide nanocrystal are swaped with tin; at the mesoscopic level, a fraction of lattice sites in an ITO nanocrystal superlattice are swapped with ITO nanocrystal with a different tin-doping amount. This combined experimental and computational study shows how to leverage this hierarchical doping to, for example, create metasurfaces with the unusual optical property of vanishing electric permittivity (i.e. epsilon near zero, ENZ).

Zachary M. Sherman, Kihoon Kim, Jiho Kang, Benjamin J. Roman, Hannah S. N. Crory, Diana L. Conrad, Stephanie A. Valenzuela, Emily Lin, Manuel N. Dominguez, Stephen L. Gibbs, Eric V. Anslyn, Delia J. Milliron, Thomas M. Truskett

Nano Lett. 2023, 23, 3030-3037

We introduce a computational technique, the "mutual polarization method" (MPM), for rapid electromagnetic simulations of large nanoparticle configurations obtained from coarse-grained molecular dynamics simulations. MPM successfully predicts and yields fundamental structure-optical property information governing colloidal gels and randomly-mixed binary superlattices self-assembled in the lab with plasmonic nanocrystals.

Zachary M. Sherman, James W. Swan

Phys. Rev. Lett.. 2020, 124, 208002

Above a critical electric field strength, an instability causes colloids in electrolyte solutions to spontaneously rotate, a phenomenon called Quincke rotation. We discovered a new mode of electrokinetic transport where Quincke rotation couples to electrophoretic translation to propel particles orthogonally to the applied field. This is an example of the "Magnus effect", which causes a spinning baseball to follow a curved path (i.e. a curveball), but at orders of magnitude smaller length scales!

This paper was featured in:

• Physics: Finding a “Curveball” Equivalent for Microscopic Particles

• MIT News: Study Finds Electrical Fields Can Throw a Curveball

Zachary M. Sherman, Michael P. Howard, Beth A. Lindquist, Ryan B. Jadrich, Thomas M. Truskett

J. Chem. Phys. 2020, 152, 140902

Suppose we want a soft material with components arranged in a specific pattern or with a particular material property. How should we build that material? This Perspective Review discusses "inverse methods" that utilize numerical optimization and machine learning to efficiently design soft materials with targeted features.

Zachary M. Sherman, Dipanjan Ghosh, James W. Swan

Langmuir 2018, 34, 7117-7134

Paramagnetic colloidal nanoparticles in a magnetic field and dielectric nanoparticles in an electric field can self-assemble into colloidal crystals, but modeling and predicting these phenomena is difficult because the interparticle interactions driving assembly are many-bodied (i.e. they cannot be represented with a pairwise potential). This paper shows how to incorporate many-bodied ``mutual polarization'' into both dynamic simulations and statistical thermodynamic theory to accurately model field-directed colloidal assembly. 

Zachary M. Sherman, James W. Swan

ACS Nano 2016, 10, 5260-5271

Self-assembly of colloidal nanoparticles is either fast (good) & error-prone (bad) or defect-free (good) & slow (bad). Cyclically toggling the interparticle interactions on and off over time drives out-of-equilibrium assembly that is fast & defect-free (both good!).