The calculated molecular layer heights are in good agreement with the two experimental heights of 0.6 ± 0.2 nm and 0.9 ± 0.1 nm, before and after annealing, respectively. The height measurement of the as-deposited TEMPO layer in Figure , agrees with that predicted for a tilted configuration, suggesting that prior to annealing, the molecular arrangement is more disordered and the TEMPO-TEMPO interaction weaker. In comparison, the measured height of the postannealed sample in Figure compares well to the calculated upright antiparallel arrangement (structures 1 and 2). These results are consistent with the expectation that postannealing will provide sufficient energy to the molecular system to promote reorganisation, therefore resulting in the most stable molecular configuration consisting of a 50/50 arrangement of upwards and downwards facing functional NO groups.