Unusual thermal stability of a site-ordered MC60 rocksalt structure (M=K, Rb, or Cs)

X-ray diffraction and differential scanning calorimetry of MxC60, with x∼1 and M=K, Rb, or Cs, reveal an unusual T-dependent phase sequence. A low-symmetry ground state is found, while the high-T limit is an ordered rocksalt structure in which only the octahedral sites are occupied. The unusual high-T stability of this ordered phase is attributed to the entropy of molecular orientational disorder and/or thermal disorder of the alkali-metal ions within the octahedral sites. Unique to KxC60 with x1.4, we find at intermediate temperatures an fcc site-disordered lattice gas phase with random occupancy of tetrahedral and octahedral sites, which is thus isostructural with superconducting K3C60

EFFECTS OF LIGHT AND TEMPERATURE ON COLOUR CHANGES IN RIPENING FRUIT OF ACTINIDIA MACROSPERMA

Unripe, green fruit of Actinidia macrosperma turn an intense orange during ripening on the vine or after harvest. The change in colour is due to degradation of chlorophyll and synthesis of carotenoids. Temperature and light can influence the rate of colour change during storage of the fruit. Fruit harvested green and then stored at room temperature (c. 20\ub0C) quickly turned a bright orange colour, irrespective of light regime. Green fruit stored at 4\ub0C did not turn orange but instead became white or pale yellow over a period of 10 weeks. If these fruit were then shifted to room temperature, they rapidly turned bright orange. Changes in fruit colour during storage appear to be affected more by temperature than by light. It is concluded that carotenoid biosynthesis is more strongly affected by temperature than is chlorophyll degradatio