ABSTRACT
The Œrst overtone of the C-H stretch next to a double bond occurs at a higher wavenumber (lower wavelength) than saturated C-H stretch absorptions. This peak is strong and distinct in some structures, particularly the methylene group of terminal double. In most cases, however, it is weak and difŒcult to locate especially in the presence of methyl groups. The band position is near 6100-6200 cm-1 (1640-1612 nm).
