CAREER: Directed Molecular Design of Chromophore-Radical Dyads for Optical Pumping of Doublet Ground States

New York University, New York NY

Investigators

Abstract

With support from the Chemical Measurement and Imaging Program in the Division of Chemistry, and partial co-funding from the Chemical Mechanism, Function, and Properties Program, Dr. Claudia E. Avalos and her group at New York University are designing and characterizing molecules intended for applications in quantum sensing and nuclear magnetic resonance (NMR) signal enhancement. Molecules that can be classified as good quantum spin sensors often exhibit properties that also make them good candidates for NMR signal enhancement. In both cases, the molecule’s spin state should be readily controlled by the application of some form of electromagnetic radiation. Using a combination of computational and experimental techniques, the Avalos lab is seeking to identify the magnetic and structural motifs that facilitate optically induced spin control. Identification of classes of molecules that exhibit these properties would have a significant impact on improving the performance of magnetic resonance methods (which are widely used in chemical industry) and quantum sensor designs (with applications such as gyroscopes, magnetic field detection, and nanothermometry). Dr. Avalos is also engaged in educational activities involving magnetic resonance methods at both the local and national level through workshops that aim to help educators explain and incorporate magnetic resonance tools into their physics and chemistry curriculum at the high school and undergraduate level. The ability to optically generate highly polarized nuclear spin states with chromophore-radical (C-R) dyads has the potential to enable highly sensitive multi-dimensional NMR with sample-limited systems without the need for cryogens or expensive microwave sources. Given the vast chemical space that is possible in C-R systems, combined computational and experimental studies are vital to aid in the rational design of C-R molecules with desired electronic and spin properties. Dr. Avalos is seeking to determine how the C-R structure is correlated with the mechanism of polarization of the radical as well as how this structure affects the polarization transfer mechanism to neighboring nuclear spins. Improved understanding of the relationship between mechanism and structure should facilitate design of molecules with desirable magnitude and sign of the spin polarization generated as well as provide guidance for the magnetic field and temperature conditions where polarization may be accessed. The dominant mechanisms rely on an interplay of spin-spin coupling, magnetic anisotropy, orbital overlap, and sources of spin relaxation. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.