The ground state absorption spectra for all samples were collected using a Shimadzu UV-3600i Plus spectrophotometer under ambient conditions. The solution UV-Vis spectra were recorded in quartz cells with a 10 mm path length. The photoluminescence emission and excitation spectra were measured on Fluorolog-3 spectrometer (Horiba) with a 0.2 s integration time and reference corrected for excitation light source and emission spectral response. The emission lifetimes of the samples were measured on Lifespec II (Edinburgh Instruments) time-correlated single photon counting (TCSPC) fluorescence lifetime spectrometer using a 375.4 nm pulsed laser diode. A pump-probe micro-millisecond transient absorption (TA) spectroscopy set-up was used to measure the TA spectra and kinetics. Laser pulses (repetition rate 10 Hz, pulse duration 6 ns) were generated by a Nd:YAG laser (Spectra Physics, INDI-40-10). Excitation wavelengths were selected by a versaScan L-532 OPO and the excitation density was set in the range between 0.3 and 120 mJ cm - 2 using neutral density filters, measured by a ES111C power meter (Thorlabs). The probe light was provided by a quartz tungsten halogen lamp (IL1, Bentham). Probe wavelength selectivity was achieved using bandpass filters and a Cornerstone 130 monochromator (Oriel Instrument) before the detector. The TA signals were recorded with Si and InGaAs photodiodes. The signal from the photodiodes was preamplified and sent to the main amplification system via an electronic filter (Costronic Electronics), which was connected to an oscilloscope (Tektronics, DPO4034 B) and PC. The degassed solutions for the TA spectroscopy were prepared using three repeat freezepump-thaw cycles. The concentration of the samples was chosen to maintain the optical density of 0.2 contained within 0.2 cm path length quartz cuvette.