โ Scribed by P. Costa Bizzarri; C. Della Casa; S. Pietra
No coin nor oath required. For personal study only.
In our previous work 1 it was seen that the photoconductivity of s-trithiane is primarily due to surface defects, introduced by means of thermal treatments or ageing.
In this communication we report the influence of thermal treat, ment, of impurities and of crystal growing on the activation energy of dark conductivity. This furnished an opportunity to check the validity of the Meyer-Neldel rule 2 or compensation law for the case of trithiane.
Commercial trithiane (Fluka purum) was purified by subsequent application of the following procedures: a) two crystallizations from glacial acetic acid; b) recrystallization from toluene 3 ; c) continuous adsorption chromatography 4 with benzene as eluent and silica and alumina as adsorbents; d) vacuum sublimation. The whole cycle of purification was repeated a second time, with the exception of c). With the ultra-purified trithiane two types of single crystals were prepared: the first was grown from benzene solutions, with the spectrograde solvent purified removing thiofene (detection with isatin s ) and dried over sodium wire; the second was grown from the vapour in presence of nitrogen by the sublimation device described by Sloan et al. 6 . A third type of single crystals (impure) was prepared from commercial trithiane partially purified only by the procedure a), providing growth from spectrograde benzene solutions.
The crystal selection and the electrical measurements were carried out as previously described 1 ; the electric field was applied parallel to
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