The infra-red absorption spectrum of methylamine vapour
| Autor: | E. F. Daly, C. R. Bailey, S. C. Carson |
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| Rok vydání: | 1939 |
| Předmět: | |
| Zdroj: | Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences. 173:339-348 |
| ISSN: | 2053-9169 0080-4630 |
| DOI: | 10.1098/rspa.1939.0149 |
| Popis: | The electronic configuration of a single bond is usually such as to permit free rotation about the direction of the bond. Experimental evidence from specific heats and dipole moments shows generally that at ordinary temperatures the expected free rotation does not occur. There are two explanations available. In the case of molecules such as hydrazine and hydrogen peroxide the rotation is completely restricted and the corresponding degree of rotational freedom is replaced by a vibrational mode; the interaction of the electronic clouds of the two bonded atoms produces a lack of axial charge symmetry about the bond and largely confers the rigidity of a double bond upon the structure (Penney and Sutherland 1934). This effect would not be dependent on temperature. In the second explanation the inhibition is due to interaction between extreme atoms, as in the case of ethane (Eucken and Schäfer 1939; Pitzer 1937). A torsional vibration results which may become more nearly free rotation as the rotational quantum numbers increase, or again with rise in temperature. Methylamine is a molecule in which a simple theory would indicate free rotation about the C—N link. The fine structure of an infra-red band or the contour of its envelope should provide information about the rotational conditions of such a molecule (Nielsen 1931). We have therefore examined the infra-red absorption spectrum of the gas and find that the band envelopes are largely those of an approximately symmetrical rotator with almost completely inhibited internal rotation. |
| Databáze: | OpenAIRE |
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