Spectral hole burning in dye solutions

Using picopulses generated by a mode-locked ruby laser, we have measured the 3-8-Å bandwidth of a hole burned in the 0-0 transition of cryptocyanine in methanol and demonstrated the inhomogeneous chatacter of this transition. The population-rate equations are written for an inhomogeneous transition with two and four energy levels interacting with continuous or pulsed excitation. Using the numerical solutions of this model together with the experimental result we determine a transverse relaxation time T₂ = 0.6-1 ps for cryptocyanine in methanol.