Transient absorption and higher-order nonlinearities in silver nanoplatelets

We show that the imaginary parts of higher-order optical nonlinearities and their decay times can be determined by a time-intensity domain analysis of the conventional transient absorption data. Using this method we have measured the values and decay times of third, fifth and seventh-order nonlinear susceptibilities of silver nanoplatelets in water. The origin of these higher-order nonlinearities is explained using a two-temperature model.