Fig. 2: Phased Two-dimensional Electronic Spectra of Single and Connected Aggregates.

Representative absorptive 2DES spectra of (a) isolated ZnOPPc aggregates (average of n = 5 spectra) and (b) HOF at 20 fs (average of n = 10 spectra). (c) normalized and offset photoinduced absorption (shaded error bars are 1 standard error in the mean) and (d) ground-state bleach feature time traces from 2DES data from the marked points in a and b (shaded error bars are 1 standard error in the mean). Pump, probe and local-oscillator polarizations are kept parallel to each other when collecting this data. In a, b, c, and d, • is located at excitation wavelength = 660 nm and detection wavelength = 630 nm and represents ground state bleaching dynamics. ▼ represents the photoinduced absorption feature at excitation wavelength = 650 nm and detection wavelength = 595 nm. Source data for a, b, c, and d are provided as a Source Data file. e Energy-level diagram of the aggregate bands to depict biexciton formation and the negative PIA feature observed in both aggregates in a and b. The corresponding biexciton (|\({ee}\)〉) formation Feynman pathway is shown in (f). Pump interactions are shown in maroon. The probe interaction, or biexciton formation process, is shown in black.