Fluctuations in absorbance observed for photoexcited ferrocene-doped poly(methyl methacrylate) thin films containing chloroform molecules as impurities

Photooxidation of Some Metallocenes in a Polymer Matrix

“…After recording the absorption spectrum for a photoexcited ferrocene-doped PMMA film, the film was kept in air and the changes in absorption spectrum was checked as a function of time. Fluctuations in absorbance associated with the time-dependent changes in its value under various experimental conditions such as varying the duration of photoexcitation, photoexcitation wavelength and concentration of ferrocene in the PMMA films [ 43 ] were noticed. With increasing time after ceasing the photoexcitation, the nature of observed gross change in absorbance [ 43 ] is a clear indication for the change in the concentration of ions, radicals and other species formed due to secondary reactions.…”

“…Fluctuations in absorbance associated with the time-dependent changes in its value under various experimental conditions such as varying the duration of photoexcitation, photoexcitation wavelength and concentration of ferrocene in the PMMA films [ 43 ] were noticed. With increasing time after ceasing the photoexcitation, the nature of observed gross change in absorbance [ 43 ] is a clear indication for the change in the concentration of ions, radicals and other species formed due to secondary reactions. The observed fluctuations in absorbance seem to indicate the diffusion of small chemical species in polymer matrix and its thickness determine the time scale of observed fluctuation [ 43 ].…”

“…With increasing time after ceasing the photoexcitation, the nature of observed gross change in absorbance [ 43 ] is a clear indication for the change in the concentration of ions, radicals and other species formed due to secondary reactions. The observed fluctuations in absorbance seem to indicate the diffusion of small chemical species in polymer matrix and its thickness determine the time scale of observed fluctuation [ 43 ]. Similar studies in the case of other metallocenes will be carried out in the future.…”

Photoinduced anomalous current changes in some organometallic materials

“…Ferrocene and some of its derivatives have wide applications in various fields e.g., these materials have been used (i) efficiently as mediators in various electron transfer processes [2], (ii) in the development of biosensors [2], (iii) for the synthesis [5] of new materials of higher electrical conductivity from poly(vinylidene chloride) and (iv) for the preparation of charge transfer compounds with organic solids [4,6]. Previous studies [7][8][9][10][11][12][13][14][15][16][17] in our laboratory, on the dark conductivity [7][8][9][10] and photoconductivity [11][12][13]17] as well as spectroscopic properties [14,15] (of ferrocene, its some derivatives and few other metallocenes) under various experimental conditions have offered some interesting results. The results include adsorption-induced phase transition [7,8] in ferrocene and its some derivatives upon adsorption of organic solvent vapours; current oscillations in the vapouradsorbed state [9,10]; photoinduced charge transfer [14,15] between a metallocene (ferrocene, its derivatives or other metallocene) and chloroform molecules confined in a poly(methyl methacrylate) (PMMA) thin film; observation of fluctuations in absorbance for ferrocene-doped PMMA thin films containing chloroform molecules after photoexcitation [16]; photoswitching property [17] of ferrocene-doped PMMA thin films, etc.…”