CHEM 213 Lecture Notes - Lecture 11: Rotational Energy, Bond Length, Fundamental Frequency
6 Oct 2016
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Document Summary
Vibrational levels fare causing the hairy lines in the spectrum. Lots of vibrational levels populated-->gives rise to lots and lots of lines. Rotation around an axis perpendicular to bond axis or rotation around the bond axis. Compared to stretching the bond, rotation around the bond axis takes relatively little energy. Energy of rotation equation: (h^2/8pi^2i)=constant=>denoted b=> units is either joules or wave numbers. Rotational energy increase level spacing increases with j. Levels get increasing larger in energy apart. Not allowed to have delta j = 0 fundamental frequency is missing due to selection rules. Right side is higher energy for a given value than the left hand side. There are two sides because delta j = +/- 1 isotopes change position, thus, di erent lines. But also, level j has a degeneracy of 2j+1 (from quantum mechanics) If you go to high j levels the bond will stretch.
