Extraction of absorption spectra of some polyenes produced in poly(vinyl alcohol) film utilizing photodegradations by monochromatic light

Individual absorption spectra of (CHCH)n (n=2–5) produced in heated poly(vinyl alcohol) (PVA) films can be extracted separately by selective photodegradation. Difference spectra between the two spectra obtained at various different irradiation times did not show the spectra of individual polyenes owing to overlapping of the spectra due to degraded and produced polyenes. By proper combination of irradiations, however, the other spectra could be eliminated, and each spectrum of n=2–5 could be extracted. For n=4 and 5, the second bands were revealed.