Like Cl-GQD, the Cl-GNR exhibits long-lived photo-generated intermediates (Figure ). Transient absorption spectra of Cl-GNR consist of two ground-state bleach peaks at 500 and 600 nm, as well as a broad excited-state absorption feature at ~700 nm. The 500 and 600 nm bleach bands undergo red and blue-shifts, respectively, during the first nanosecond after the excitation pulse (Figure ), while the measurements in the longer time-window show a decay of the signal on the microsecond timescale (Figure ). Global fitting of these transient features using a sequential 1 → 2 → 3 → 4 kinetic model provided satisfactory reproduction of the kinetic behavior (solid lines in the insets of Figures and) with the following lifetimes: 0.6 ps, 6 ps, 300 ps and 106 s. The 0.6 ps, 300 ps and 106 s lifetimes are like those observed in Cl-GQD and are accordingly assigned to the Sn → S1 internal conversion (0.6 ps), S1 → T1 intersystem crossing (300 ps) and T1 → S0 deactivation (106 s), as summarized by the Jablonski diagram in Figure with component concentrations and spectra shown in Figure . The assignment of the long-lived 106 s component to the T1 state of Cl-GNR is consistent with the spin-forbidden nature of the deactivation back to the singlet ground state and is supported by its sensitivity to molecular oxygen (Figure ).