Spectrally resolved three pulse photon echoes in the vibrational infrared

Spectrally resolved vibrational photon echo measurements of the N3− ion in D2O and carbonmonoxy hemoglobin in D2O have been made using 100 fs infrared pulses in the 1800–2100 cm−1 region. These measurements allow the separation of contributions from different Feynman pathways to the echo signal, allowing comparisons of the time dependence and correlation functions for the 1–0 and 2–1 coherence terms. The spectra show good agreement with a theoretical description of the data fitted to previously determined multiexponential correlation functions. Fluctuations in the anharmonicity are found to be negligible for HbCO when the harmonic vibrational relaxation model is used.