Electron diffraction of thin-film pentacene

The structure of pentacene thin films deposited on NaCl substrates have been studied by electron diffraction. The lattice parameters of a `thin film' phase [a = 6.1 (1), b = 7.6 (1), c = 15.3 (3) Å, α = 81.0 (16), β = 85.0 (17), γ = 89.5 (9)°] were determined using a series of diffraction patterns obtained by tilting the crystal in the electron microscope. This phase has a (001) d spacing of 15.1 (3) Å. The packing of molecules in the structure is discussed.