Dipolar Correlation Spectroscopy: Higher-Order Correlation Terms in Three-Spin Double Electron-Electron Resonance (DEER)

Bettina Basel presents experimental conditions which allow to extract the three-spin contribution precisely from experimental multi-spin double electron-electron resonance (DEER) signals. The theory and concepts behind the used techniques, which are among others broadband chirp pump pulses, over coupling of microwave resonators and echo reduction measurements, are discussed and explained in detail. Moreover the setup and results of DEER experiments with newly introduced double chirp pump pulses consisting of two separate chirps are shown. Particular attention is paid to the phenomenon of orientation selection and the concept of orthogonal spin labeling.