An example is azulene : the classical explanation is that the " S " 1 and " S " 2 states lie sufficiently far apart that fluorescence is observed mostly from " S " 2.
22.
The aroma of pepper is attributed to rotundone ( 3, 4, 5, 6, 7, 8-Hexahydro-3?, 8?-dimethyl-5?-( 1-methylethenyl ) azulene-1 ( 2H )-one ), a sesquiterpene originally discovered in the tubers of cyperus rotundus, which can be detected in concentrations of 0.4 nanograms / L in water and in wine : rotundone is also present in marjoram, oregano, rosemary, basil, thyme, and geranium, as well as in some Shiraz wines.
