Vibrational energy transfer from the first excited state ͑2635 cm −1 ͒ of the O-D stretch of deuterated water ͑D 2 O͒ to the 0-1 transition ͑2075 cm −1 ͒ of the CN stretch of potassium selenocyanate ͑KSeCN͒ in their 2.5:1 liquid mixture was observed with a multiple-mode two dimensional infrared spectroscopic technique. Despite the big energy mismatch ͑560 cm −1 ͒ between the two modes, the transfer is still very efficient with a time constant of 20 ps. The efficient energy transfer is probably

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... ecause of the large excitation coupling between the two modes. The coupling is experimentally determined to be 176 cm −1 . An approximate analytical equation derived from the Landau-Teller formula is applied to calculate the energy transfer rate with all parameters experimentally determined. The calculation results are qualitatively consistent with the experimental data.