Orientational anisotropic studies by field rotation technique: Near zero-field pulsed EPR experiments of pentacene doped in p-terphenyl

Mapping the molecular axes of pentacene-d14doped inp-terphenyl single crystal using pulsed EPR technique in near zero magnetic field

“…In fact, as indicated in the Introduction, the shifts of centre frequency of PDPT in NZF along the molecular x axis are in good agreement with simple calculations based on the Hamiltonian considering only the electron dipole-dipole interaction and electron Zeeman terms [2,3]. The frequency shifts for T x -T z transition along three principal axes are given as follows,…”

“…On the other hand, we observed orderly spectral shifts of centre frequency and continuous line broadenings for PDPT when various NZF are applied along the common molecular x-axis of the doped pentacene-d 14 molecules. The shifts of the centre frequency observed in PDPT are in good agreement with simple calculations based on the electron Zeeman effect [2,3]. Although the field-related broadening of PDPT is not well understood, the fact that the shifts of centre frequency can be well characterized by considering only the electron Zeeman effect suggests that deuteron hyperfine interaction is too small to alter the centre frequency significantly.…”

“…We extended its NZF capability by adding three sets of orthogonal coils to achieve field agility in three-dimensional space. The details of the setup and other procedures have been published previously [2]. The 3D NZF orientation control enables us to perform effectively a series of NZF experiments with a constant magnitude applied at different angles within the molecular yz plane without mechanically altering the sample's position.…”

“…Our subsequent efforts were partly directed towards finding out how the near zero fields (NZF) spectral line shapes change in the fields with magnitudes on the same order as the hyperfine interactions [2]. We observed marked changes of line shape as a function of NZF magnitude and direction for both PHPT and PDPT.…”

Room-temperature solid-state maser

“…The 6 maser output power predicted by this model was fitted to the experimentally observed maser burst, yielding the green curve in Figure 3, together with estimates of three spin-dynamics parameters. Our modelling suggests that near-zero-field operation is particularly advantageous for masing: the rate of spin-lattice relaxation is low and the transition linewidth is narrow 27 .…”