ELIMINATION OF FLUORESCENCE CONTRIBUTIONS TO SINGLET OXYGEN MEASUREMENTS USING A NOVEL ELECTRONIC SWITCH

In the case of certain sensitizers, in particular those with absorptio n and emission spectra bordering on the near-IR spectral region, the d etection of singlet oxygen emission at 1270 nm is complicated by the p resence of intense fluorescence contributions at the start of the deca y. The origin of this problem is due to saturation of the input amplif ier of the digital storage oscilloscope used to acquire the data. A no vel electronic switch is described which overcomes this by controlling input to the oscilloscope amplifier. In this way, measurements are im proved to such an extent that previously unattainable values can be de termined. Using model systems, we show that the data are not distorted by the introduction of the switch. (C) 1997 Elsevier Science S.A.