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doi: 10.1007/BF03046570pmid: N/A
It is known that the atomic heat data of diamond are not satisfactorily represented over the entire range (covered by the data) by a single Debye term assuming some one value of the limiting frequency of the elastic spectrum. In the present paper it is shown that the formula fails because Debye’s hypothesis does not correctly represent the vibration spectrum of this crystal. The lattice spectrum of diamond is in fact shown by the Raman effect studies of Bhagavantam and the luminescence and ultra-violet absorption spectra studied by Nayar to consist of monochromatic frequencies down to much below the limiting frequency of Debye. The atomic heat data obtained by Pitzer agree perfectly with a formula containing Einstein terms corresponding to the spectroscopically observed frequencies of the lattice, namely 1332 cm.−1 and 780 cm.−1 and superlattice frequencies of 532 cm.−1 and 218 cm.−1, their relative weights being 4, 3, 7/8 and 1/8 respectively as indicated by dynamical considerations.
doi: 10.1007/BF03046573pmid: N/A
The character table for rock-salt derived from the theory of groups applied to the unit cell containing four atoms of sodium and four atoms of chlorine, gives eight triply degenerate normal modes of vibrations. One of them corresponds to the translations of the cell as a whole, two are infra-red active and Raman inactive, and five are inactive both in the Raman and the infra-red. The overtones of the latter five modes should however, appear in the Raman effect. This analysis of the vibration spectrum of the rock-salt structure gives a complete explanation of the infra-red absorption spectra of the alkali halides observed by Barnes and the Raman spectrum of rock-salt obtained by Fermi and Rasetti. The two infra-red absorption maxima at 161 and 247 cm.−1 are taken as the two fundamental frequencies and the five frequencies at 228, 272, 298, 346 and 366 cm.−1 identified from the Raman spectrum reproduced by Fermi and Rasetti, are assumed to be the first overtones of the remaining five frequencies of the lattice. The latter also shows three broad bands with peak frequencies of 81, 42 and 20 cm.−1 These are shown to be the octaves of the superlattice frequencies of the second, third and fourth orders.
Desai, R.; Hunter, R.; Sahariya, G.
doi: 10.1007/BF03046574pmid: N/A
Benzylation of the sodio-derivative of ethyl-1-cyano-4-methyl-cyclohexane-1-cyanoacetate yields a dicyano ester, which gives a pair of isomeric 1-carboxy-4-methylcyclohexane-1-α-benzylacetic acids on hydrolysis. Similar pair of isomeric 1-carboxy-3-methylcyclohexane-1-α-benzylacetic acids has been also obtained. These results can equally be interpreted on the uniplanar form of the cyclohexane ring.
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