Dr. Nandita Abhyankar
NIST – National Institute of Science and Technology
Biophysical and Biomedical Measurement Group
Friday, February 19, 2021
HOST: Dr. Chengpeng Chen
Nanoscale Electron Paramagnetic Resonance (EPR) Spectroscopy: what, why, and how
In this talk, I will delineate the motivation for – and our recent work in – enabling electron paramagnetic resonance (EPR) spectroscopy of electron-spin ensembles smaller than a nanoliter. Magnetic resonance spectroscopies of ensembles of electronic or nuclear spins are powerful for generating detailed atomic-level information about structure and dynamics, encoded in spectral lineshapes, field-dependences, and temperature-dependences. Many samples with volumes in the range of nanoliters to femtoliters are currently inaccessible by EPR spectroscopy. Therefore, critical spectroscopic information is hidden due to a lack of sensitivity. Additionally, detecting electron spins in sub-nanoliter volumes has potential applications ranging from quantum computing to lab-on-a-chip devices. One of the main enabling technologies of conventional EPR spectroscopy is the resonant structure used to confine microwave magnetic fields to a small volume approaching the sample volume. I will discuss the strategies used to miniaturize microwave resonators and figures of merit characterizing resonator performance, with particular emphasis on planar metal resonators patterned on dielectric substrates using photolithography. Finally, I will focus on the design paradigm we have used to achieve highly efficient planar microresonators with: (i) sub-nanoliter volumes, (ii) scalability over a wide frequency range, and (iii) potential for widespread applicability in existing spectrometers.