Absorption spectrum of trans and cis isomers of methyl red azo dye doped PMMA polymer and cis liftime measurment

Azo dye as a photosensitive molecule after absorption of a photon undergo photoisomerization between tow trans and cis isomer.cis Lif time is depend on environment of azo dye. it is from about microsecond to second.in this paper a thin film of methyl red azo dye doped in PMMA polymer is formed on quartz substrate. absorbtion spectrum of Methyl Red azo dye doped in PMMA polymer in tow Trans and Cis states is recorded. an optical set-up is arranged for measuring cis lif time.this high sensitive set-up could measure phenomena down to micosecond range. Fast Cis to Trans thermal relaxation life timein stiff matrix is measured witch is about 5 second.