Thiel's research elucidated
atomic-scale structures and processes on solid surfaces, in areas relevant to
microelectronics,
tribology,
heterogeneous catalysis, and
nanoscience. She published over 300 research papers, which have been cited about 12,000 times, effective 2019. She is especially known for work in the following three areas.
Surfaces of quasicrystals Thiel's research group pioneered studies of nucleation and growth of metal films on
quasicrystal surfaces, demonstrating that local
pseudomorphic growth, including
starfish-shaped formations, can occur at very specific nucleation sites. Focusing on metallic, aluminum-rich quasicrystals, Thiel and her collaborators extensively explored how quasicrystal atomic-scale surface structures were related to their unusual surface properties, including low friction, low adhesion, and good oxidation resistance.
Interaction of water with metal surfaces Thiel's Ph.D. research described evidence for
hydrogen bonding between water molecules on a ruthenium surface. She continued her research on water as a faculty member at Iowa State University, and discovered that desorption kinetics of water can exhibit a measurable
isotope effect. She was credited with being the first to propose that bilayers of water near solid surfaces could possess a structure similar to the basal plane of
Ice Ih. She was the co-author, along with
Theodore E. Madey, of a highly cited and comprehensive review article describing the interactions and properties of water near solid surfaces.
Nucleation, growth, and coarsening of metal nanostructures on surfaces Thiel's group was credited with discovering that large two-dimensional islands of metal
adatom clusters can have significant room temperature mobility on metal substrates, and that, contrary to what had usually been assumed, this can be the main route to coarsening (an evolution to larger sizes and fewer numbers) of these clusters. She and James W. Evans are responsible for first describing an atomic-scale mechanism for metal film growth, which they dubbed 'downward funneling'. Because of this mechanism, they predicted an unusual variation in film roughness with temperature from theory, and eventually confirmed it experimentally using
scanning tunneling microscopy. This is now accepted as an important mechanism that affects thin film morphology upon growth at low temperature. More recently, her group discovered a series of naturally occurring metal-sulfur complexes with distinct
stoichiometries, which may influence stability of larger metallic features by assisting surface metal transport and hence coarsening. She was highlighted for this work in the Journal of Physical Chemistry's virtual issue highlighting 66 women in honor of Marie Curie's 150th birthday. She and her collaborators also discovered that metallic nanoparticles can be grown as encapsulated clusters near the surface of a layered material,
graphite, if specific growth conditions are met. Applying a
continuum elasticity model, they developed insight into the reasons for the low, flattened shapes (high aspect ratios) of these embedded particles, and a prediction that the shape of encapsulated metal islands should be universal (size-independent). ==Awards and honors==