Elucidating Local Viscosity Using Fluorescence Lifetime Measurements

Certain fluorescent molecules, known as molecular rotors, can be employed to estimate the local (nanoscale) viscosity in microheterogeneous systems by measurement of their fluorescence lifetime. This can be advantageous over the usual fluorescence anisotropy method, as the measurement is simpler and faster to perform. This is demonstrated using the HORIBA Scientific TemPro fluorescence lifetime system to monitor the gelation of silica produced using the sol‐gel technique.