To further identify the spin ground state of Clar's goblet, pulse-EPR was used because of its high signal reliability at low temperatures. The echo-detected field-swept (EDFS) spectra of cg-2 were recorded at 10 K, 50 K, and 100 K, respectively. These EDFS spectra can be accurately deconvoluted into one doublet and one triplet component with relative weights by simulations (Fig. , simulation parameters are attached in the Supplementary Information). As the temperature increases from 10 K to 100 K, the triplet component substantially increases from 0.36 to 1.70 relative to the doublet component (its weight sets to 1). This thermal populated property clearly demonstrates that the triplet state is the excited state of cg-2. To further verify the spin states of the proposed doublet and triplet components in the EDFS spectra, echo-detected nutation experiments were performed using the pulse sequency tp-T-π/2-τ-π-τ-echo (T refers to waiting time). In nutation experiments, a microwave nutation pulse with duration tp, is applied to drive the spin system in the sample into a superposition of its two ms levels of a given resonance. With increasing nutation pulse length, the spin system is cycled through all arbitrary superpositions of the two ms levels, resulting in the Rabi oscillations in the detected signal. As shown in Fig. , the Rabi oscillations were recorded at the magnetic field of 3401 G, temperature of 10 K and 100 K, respectively. After fast Fourier transformation, the oscillation data are transformed into two separate frequencies corresponding to the doublet and triplet specie. The spin states of these two species are confirmed because the ratio of the Rabi frequency for the assigned triplet species (𝛺𝛺 𝑚𝑚 ±1 ↔𝑚𝑚 0 ) to that of the doublet species