ESR Studies of N@C60 and Its Derivatives in Polymer Matrices: Advances and Challenges

The paramagnetic endohedral fullerene molecule N@C₆₀ is a candidate as an electron spin based quantum information processing element due to its exceedingly long phase coherence lifetime. A lot of attention has been focused on the electron spin properties of N@C₆₀ in different environments. In terms of synthetic chemistry, a significant milestone has been the synthesis of a dimer molecule covalently linking two N@C₆₀ units. The next significant challenge is the ability to control the interaction between multiple spin centres in an array. One potential method to achieve this is to macroscopically align rigid multi spin centre N@C₆₀ molecules by incorporating them into a polymer matrix that is subsequently uniaxially drawn to align the chains. In this talk, I will present our ESR studies of the environment of pristine N@C₆₀ and an N@C₆₀-C₆₀ dimer molecule in polystyrene matrices. I will show that deuteration of the polymer has a marked positive effect on the phase memory coherence time of pristine N@C₆₀. Furthermore, I will show that deuterated polystyrene acts as a suitable polymer matrix for rigid N@C₆₀-C₆₀ dimer molecules, permitting both uniform dispersion and retention of a phase memory time (T_m) of 21µs at 40 K. This timescale is long enough to allow thousands of pulsed sequences to take place in order to manipulate the individual spin centres before decoherence can occur.