T2 selective scanning vibrational echo spectroscopy

Experiments are presented on a mixture of tungsten hexacarbonyl (W(CO)6) and (acetylacetonato)dicarbonylrhodium(I) (Rh(CO)2acac) in liquid dibutylphthalate (DBP) in which the spectrum of the asymmetric CO stretching modes (∼2000 cm−1) is taken by continuously scanning the frequency of a ps vibrational echo pulse sequence and observing the vibrational echo intensity. While the absorption spectrum shows a large solvent background with DBP vibrational peaks, the vibrational echo spectrum is background free and contains only the W(CO)6 and Rh(CO)2acac peaks. When the delay between the vibrational echo pulses is changed, the ratio of the W(CO)6 and Rh(CO)2acac peaks changes because of differences in their homogeneous dephasing times.