Figure 2. Phtoinduced free-carrier generation probed by microwave conductivity.

(a) Representative time-resolved reflected microwave transients for (red and blue) (7,5)-SWCNTs suspended in toluene and (grey, left y axis) PFO dissolved in toluene. The SWCNT transients result from photoexcitation at either the S₂₂ transition (blue, left y axis) or S₁₁ transition (red, right y axis). (b) Frequency-dependent reflected microwave power transients for (7,5)-SWCNTs suspended in toluene, following excitation at S₂₂. In a, a biexponential fit is displayed as the solid black line. Experimental conditions: the excitation photon fluence was approximately 1.0–1.5 × 10¹² photons per cm² for the data presented in a and 4.4 × 10¹² photons per cm² for b; 5 ns pulse width; room temperature.