What Has Been Achieved: Ultrafast optical pump-probe measurements of sound velocity, elastic constants, and phonon lifetimes in TMD crystals.
Importance of the Achievement: Phonon lifetime measurements for these novel materials are rare, and they are useful in predicting thermal conductivity. Also the strong reflectivity signals produce by these relatively small elastic strains are a promising indicator of the future effectiveness of these materials as transient ultrasonic strain sensors.
Unique Feature(s) of the MIP that Enabled this Achievement: 2DCC-MIP’s Chemical Vapor transport (CVT) growth of high-quality single crystals of TMDs for exfoliation. The MIP creates an environment whereas users of all career levels are encouraged to participate directly, access and analyze user project data and contribute to publications. In this external user project 5 of the Vassar co-authors were undergrads at the time of their work on the project. Undergraduate Thompson is now in the PhD program at the Univ. of Washington.
Publication: E. Thompson, E. Manzella, E. Murray, M. Pelletier, J. Stuligross, B.C. Daly, S. H. Lee, and R. Redwing, “Picosecond laser ultrasonic measurements of interlayer elastic properties of 2H-MoSe2 and 2H-WSe2,” Mater. Today Chem. 2020, 18, 100369, https://doi.org/10.1016/j.mtchem.2020.100369.
The authors acknowledge the support of National Science Foundation award number DMR-1709521 “RUI: Acoustic Phonons in Nanostructures: Surface Waves, Thermal Transport, and Imaging.” This study is based upon research conducted at The Pennsylvania State University Two-Dimensional Crystal Consortium – Materials Innovation Platform (2DCC-MIP) which is supported by NSF cooperative agreement DMR-1539916.