Photophysical Aspects of FCS Measurements

摘要: Photophysical and photochemical aspects of dyes are great importance for applications fluorescence spectroscopy where a high read out rate or sensitivity is required. The need to optimize the fluorescence, both with respect total number photons that can be extracted as well itself, especially pronounced in regarding single molecule detection correlation (FCS), low signal not compensated by an increased fluorophore concentration. In past, photophyscial limitations have also, large extent, restricted use FCS. Although concept first experimental results FCS were presented more than 25 years ago [13.1-13.3], has not, until last five ten years, started find extensive use. early technique, efficiency combined limited photostability fluorophores method. High background intensities, dominated Raman scattering water molecules, made it impossible reduce concentrations without having dominating over signal. As consequence, concentration fluorescent molecules under investigation had high, leading lower relative fluctuations fluorescence. To able distinguish analyze amplitudes fluctuations, long measurement times often necessary.