Nanosecond Broadband Transient Absorption Spectroscopy. Nanosecond broadband transient experiments were conducted to observe the dynamics of 6MP after the 3 ns limit of the mechanical delay stage of the femtosecond Helios spectrometer (Ultrafast Systems, LLC). Its methodology and experimental setup have been previously detailed. In brief, the same Ti:Sapphire amplifier system (Libra-HE, Coherent, Inc) was used to pump the OPA (TOPAS, Quantronix/Light Conversion) and generate the excitation wavelength of 334 nm used for the experiments. An electronically triggered broadband white light source (Eos, Ultrafast Systems, LLC) was used to generate a probe pulse with a spectral window from ~375 to 800 nm, a temporal window of up to 90 μs and a time resolution of 400 ps. This light source was coupled to the Helios spectrometer and the data was collected using a homemade LabView (National Instruments, Inc.) software.