Vibrational Spectroscopy and Modeling of Quantum Dot-Molecule Interfaces
We are using electronic structure theory to study how the vibrations of the ligands on the quantum dots participate in thermal dissipation from the excited state. In radiationless decay, the energy of the quantum dot’s excited state is used to excite vibrations in the system. We’re interested in how we can change the chemical structure of the interface to control the competition between radiative and radiationless decay rates.
The direct measurement and control of energy dissipation pathways in a nano-material is perhaps the single biggest challenge for maximizing efficiency and minimizing losses in photochemical or photophysical processes. Changes to molecular vibrations provide a method for tracking the structural changes a molecule-QD complex undergoes as it interacts with a photoexcited electron or hole.
Here, we utilize a mid-IR detector and an ultrafast laser to track vibrations in the molecule as well as the photoexcited electron and hole as a function of time to observe energy dissipation mechanisms.
Transient Absorption measures the change in the absorbance of a particular wavelength over time as the result of a photoexcitation caused by a pump laser. We can utilize a mid-IR detector to look for changes in molecular vibrations to track electron and hole migration within the nanostructure.
Sponsored by the Army Research Office through a Presidential Early Career Award for Scientists and Engineers (PECASE)