Synchrotron radiation as an excitation source in time-domain and frequency-domain fluorometry

Synchrotron radiation is an excellent excitation source for both the time-domain (pulse) and the frequency-domain (phase/modulation) methods of time-resolved fluorescence spectroscopy. All possible wavelengths are available to excite fluorescent biological probes since synchrotron radiation consists of an intense continuum of energies from the IR to X-rays. The pulsed nature of synchrotron radiation permits time-correlated single photoncounting techniques to collect a histogram of the probability of the decay of the excited state. The harmonics of the pulsed exciting light also provide a wide range of modulation frequencies that permit the frequency-domain method to match the current resolution for time-domain measurements.