ABSTRACT
The phase-matched photon echo signal field should then satisfy the following wave vector equality: ks = -k1 + k2 + k3. The corresponding diagrams have been called the rephasing ones. The “mirror image” echo appears at ks = k1 - k2 + k3, and the corresponding nonlinear optical transition pathways were called the nonrephasing diagrams. At short time (<τsol or τdecoherence), the rephasing echo and the mirror image (nonrephasing) echo signals, with respect to the first coherence period, τ, do not completely overlap,9 and the time difference between the two peaks was defined as the three-pulse PEPS denoted as τ*( ).T 7, 10, 11 It turned out that the PEPS as a function of the second delay time T between the second and third pulses in the three-pulse photon echo was shown to be directly related to the transition frequency-frequency correlation function, and its asymptotic value is related to the static inhomogeneity directly reflecting unequal environments around different chromophores.7, 11 The delay time T was called the waiting or population evolution time in the literatures. Usually, the conventional integrated photon echo signal depends on two time variables τ and T, and the echo field intensity (not amplitude) was detected. Therefore, the integrated photon echo measurement method cannot provide the 2D photon echo spectrum unless notable quantum beats exist.
