Isosbestic points in emission spectra

Auxetic springs for seating

“…However, the aggregated PDIs exhibit an inverted intensity distribution among their vibronic states with A 0→0 /A 0→1 ≤ 0.7. 15 As depicted in Table 2, the A 0→0 /A 0→1 ratios for chloroform and TCE are 1.24 and 1.20, respectively, which shows that it is weakly aggregated in these solvents. In another nonpolar solvent, toluene, LPPDI exhibited 2 slightly blue-shifted peaks (3-7 nm) at 524 and 488, and a shoulder at 456 nm, which correspond to 0-0, 0-1, and 0-2 electronic transitions, respectively.…”

“…In addition, the absorption intensities ratios of the 0→ 0 to 0→ 1 bands, both in solution and solid states, indicate a weak aggregation tendency, even at a concentration of 1 × 10 −5 M (Table 2, CHCl 3 A 0→0 /A 0→1 = 1.23, etc.). 15 In the solid state, LPPDI has a ratio of A 0→0 to A 0→1 of 1.06 (Table 2), which implies an intermediate case, indicating both aggregated as well as monomeric molecules, probably due to intermolecular π − π stacking and hydrogen bonding interactions. 17−22 Perylene dyes show astonishingly high fluorescence in solution, which is strongly quenched by π stacking in the solid state.…”

Isoemissive Photoluminescence from a Quaternary System of Valley-Polarized, Defect-Bound Excitons and Trions in Two-Dimensional Transition Metal Dichalcogenides

“…Plots of PL intensity versus gate voltage for excitons and trions are shown in Figure 5a, and the linear dependence of both plots suggests exciton and trion populations varying linearly with carrier density without significant voltage-dependence in the radiative recombination rate. It has also been shown generally that the presence of an isoemissive point is indicative that, at the isoemissive wavelength, the quantum efficiencies of each individual component are independent of the controlled parameter, 3 which is the gate voltage in this case. Therefore, our data suggest that, under these experimental conditions, radiative efficiencies are voltage independent and assume k C to be the only voltage dependent term and all other rates to have negligible voltage dependence.…”

“…This observation appears at first to contradict the earlier statement of voltage-independent radiative efficiencies as a requirement for isoemissive points. 3 To investigate this, we isolated trion PL emission from the same WS 2 device by measuring back-gated PL pumped with 473 nm light. Under such excitation, only the trion was observed, as seen in Figure 5b.…”

“…1 In the case of intersecting fluorescence spectra, the crossing points are referred to as isoemissive points. 2,3 When encountered, isoemissive points are evidence for the presence of two and only two coexisting emitting components within the system under investigation. 4,5 However, as we show in this work, isoemissive points are surprisingly also observed in a quaternary system of light-emitting species existing in transition metal dichalcogenide monolayers, and we analyze the conditions necessary for the phenomenon to occur.…”