An X-ray investigation of the structure of naphthalene and anthracene

In the present paper an attempt is made to develop a geometrical structure factor which will account for the intensity distribution in the various spectra of naphthalene and anthracene. Such an attempt is surrounded by many difficulties owing to the relatively low symmetry of the crystal systems (monclinic), the complicated nature of the molecules, and uncertainties regarding the laws of reflection of X-rays from organic crystals. Recently, however, Dr. Müller has investigated the structure of a long chain hydrocarbon making the simplication of treating a carbon atom and its attendent hydrogen atoms as one scattering centre for X-rays. The success of this investigation makes it seem probable that an approximate structure may likewise be obtained for some of the more complicated aromatic compounds. The simple organic compounds of this type (benzene, cyclohexane) are very often liquids or low melting solids that call for a specialised and difficlut technique in any investigation of their crystal structure. Good crystals of naphthalene and anthracene, however, are easily obtained. Morever the crystal structure of these compounds has already been investigated very fully by Sir William Bragg, both by the ionisation spectrometer and photographic methods. The author has had the privilege of assisting in some of this later work, and the present paper is a continuation of these investigations.