RAISE-TAQS: Quantum-based chemical sensing

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The goal of this project is to explore novel approaches to chemical sensing and analysis. This approach based on a quantum-mechanical property of electrons known as spin. Diamond samples containing a special defect, the nitrogen vacancy (NV) center. One of the carbon atoms in the diamond is replaced by a nitrogen atom adjacent to a vacancy. Such samples emit light in a way that is altered by the presence of spins on nearby molecules. In this project, chemists, physicists, and electrical engineers are collaborating to make diamond samples with arrays of NV centers placed at very specific locations beneath diamond surfaces. They then investigate how the light emitted by the NV centers depends on the location and distance of molecules located immediately outside of the diamond sample. Because spin-based chemical sensors do not currently exist, this work has the potential to lead to new types of chemical sensors with very high sensitivity, possibly at the single-molecule level. If successful, spin-based chemical sensors would be useful in a wide range of chemical, environmental and biomedical applications. In addition to training graduate and undergraduate students in the quantum-based science, the researcher team is also engaged with outreach events and development of public-friendly podcast on quantum-based chemical detection.The goal of the research is to explore fundamentally new approaches to detecting and measuringmolecular binding, cleavage, and dynamical motions at surfaces by exploiting the unique quantum mechanical properties of NV centers in diamond. The new sensing approach is based on characterizinghow electron spins of NV centers interact with spins present in molecules located nearby at the diamond-water interface. Nanolithographic patterning and ion implantation methods are being used to prepare samples containing arrays of NV centers, each of which can be probed and manipulated individually. Nanophotonic methods are being used to provide efficient ways of optically coupling light from individual NV centers to optical detectors. The diamond surfaces are being functionalized with molecules containing well defined spin probes that interact with the sub-surface NV centers in a manner that depends on the proximity between the spin probe and the NV centers. Researchers are using the resulting interactions between the spin of the molecules and the spin of the NV centers as a potentially novel approach to chemical sensing in which binding or release of molecules from surfaces is reported via spectroscopic changes in the NV centers.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.