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Photoacoustic detection technique is employed to investigate two-photon absorption (TPA) effects in ZnS over a wide frequency range with polarized 5 nsec dye laser pulses. By analyzing the dispersion and polarization dependence of TPA, we find that near the band gap, the TPA in ZnS occurs via allowed-forbidden type one-step, two-photon transitions.
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Bae et al. (1982) studied this question.
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