Fig. 4: Photoinduced long-lived ground-state spin polarization.
a, Half-field (left) and full-field (right), dark, continuous-wave X-band ESR spectra at 298 K which show the |Δms| = 2 transition in a 0.1 wt% doped polystyrene film (black dots) and the simulation (red line) of all features as a triplet species. b, The EDFS spectrum of the diradical. c, Rabi oscillations measured at the 345.62 mT transition using different microwave powers. d, The Rabi-frequency spectrum plotted for different microwave powers. The inset shows the shift in the peak frequency with decreasing microwave attenuation, and we observe an expected frequency decrease for every 3 dB increase in attenuation. e, trESR spectral slices derived at the beginning of each temporal decade (102 to 105 ns) of a 0.1 wt% doped polystyrene film of M2TTM-3Flr-M2TTM diradical at 200 K. The spectra are obtained at the quoted time point after a 532 nm laser excitation lasting for 5 ns, which repeats at a frequency of 100 Hz. The data highlight the long-lived photogenerated spin-polarized ESR signals persisting beyond 200 μs. The simulation of the 100 μs slice (green solid line) confirms polarization in T+. f, The kinetic traces of the trESR signal in the 345–348 mT region, which is the kinetics of light-induced spin polarization observed from the ESR signal, for the 0.1 wt% doped polystyrene film at 200 K (black solid lines) of the M2TTM-3Flr-M2TTM diradical. Norm., normalised; a, absorption; e, emission; n.u., normalized units.
