Smekal theory

This theory was based on the bond nature of material. According to Smekel, glass-forming melts faU into two categories, i.e., 

Inorganic compounds containing containing partially covalent and partially Ionic bonds. 

Organic/lnoiganic compound forming chain structures via Vbn der Waals bonds between the chains and covalent bonds within chains 

Smekal considered that pure ionic or pure covalent materials cannot form glasses because a covalent bond exhibits sharply defined bond angles, hence limiting the formation of a non-periodic network. Highly ionic bonds do not form network stmctures due to lack of directional characteristics. 

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Already in 1923 Smekal > postulated the existence of frequency-shifted scattered radiation on the basis of quantum theory. He gave the energy relation... 

With these new, accurate data, Smekal,4 Coster,8 Dauvillier8 and Wentzel6 have constructed atomic systems to explain the source of each known emission line. The systems are based on the Bohr-Sommerfeld theory of the origin of characteristic X-radiation. In developing and discussing their systems, these investigators have used the values of the L absorption limits measured by us. Certain criticisms have been made of a few of our values. It has therefore seemed desirable to measure some of the limits again. 

To conclude this section, there is one other phenomenon we should like to discuss, viz. the Raman effect. Let it be mentioned beforehand, however, that this is not a revolutionary discovery, like, for example, the discovery of the wave nature of the electron, but an effect which was predicted by the quantum theory (Smekal (1923), Kramers-Heisenberg) some years before it was found experimentally, though it can also be explained within the framework of classical physics (Cabannes (1928), Rocard, Placzek) its great importance rests rather on the facility with which it can be applied to the study of molecules, and on the colossal amount of material relating to it which has been accumulated so quickly. The effect was discovered simultaneously (1928) by Raman in India, and by Landsberg and Mandelstam in Russia. They found that scattered light contains, in addition to the frequency of the incident light, a series of other frequencies. 

There has been discussion as to the size and distribution of the Smekal blocks in a mosaic crystal. Zwicky(i8) suggested that a lattice is subdivided into a periodic block structure with definite spacings, basing his theory in part upon the appearance... 

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