Two-photon circular dichroism

Two-photon circular dichroism (TPCD), the nonlinear counterpart of electronic circular dichroism (ECD), is defined as the differences between the two-photon absorption (TPA) cross-sections obtained using left circular polarized light and right circular polarized light (see Figure 1). == Background == Typically, two-photon absorption (TPA) takes place at twice the wavelength as one-photon absorption (OPA).

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