Fig. 6.

Excited-state dynamics by ultrafast time-resolved spectroscopy. a, b Femtosecond transient-absorption (fs-TA) spectra of COTh in MeCN at different time delays acquired after femtosecond laser excitation at 267 nm. Inset: kinetic traces at 440 nm (black circle) are inserted in b. d, e fs-TA spectra of COTh film at different time delays acquired after femtosecond laser excitation at 267 nm. Inset: kinetic traces at 470 nm (black circle) are inserted in e. c and f Contour plots of the time-resolved absorption spectroscopic responses are shown. $\mathrm{\Delta OD}=\log \frac{{\mathrm{I}}_{100}}{I_T{\left(t,\lambda \right)}^{\prime }}$, I₁₀₀ is the light level measured through the sample before excited states are created, I_T is the transmitted light through the sample