The O–H Band in the Vapors of Some Organic Acids and of Tertiary Amyl Alcohol in the Region λ9700

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Abstract
Absorption bands corresponding to the third harmonic of the O–H vibration have been observed in the vapors of formic, acetic, propionic and trichloracetic acids, with centers at about 10202.8, 10242, 10235 and 10250 cm‐1, respectively. Formic acid alone gave a band with resolvable fine structure, but this has unusual features and may be described as a hybrid. The simultaneous presence of characteristics similar to those of both ``perpendicular'' and ``parallel'' type bands of symmetrical molecules is due to the fact that the change in electric moment produced by the O–H vibration has components along two of the principal axes of the molecule. Rotational constants for the formic acid molecule have been evaluated and the moments of inertia were found to be 85.2, 74.4 and 10.81×10‐40 g cm2. The structures of the organic acid molecules are discussed and a comparison is made with nitric acid. In tert‐amyl alcohol a band with single broad maximum at about 10414 cm‐1 was found.