Two-dimensional correlation spectroscopy in analyzing the excitation wavelength dependence of ring breathing mode of 2,2′-dipyridylketone

Excitation wavelength dependent intensities of selected Raman bands of 2,2′-dipyridylketone molecule has been explored using generalized two-dimensional correlation spectroscopy. From the correlation spectra it is found that the apparent single peak at 993 cm−1, previously assigned as ring breathing mode, is essentially composed of multiple bands and as well the relative weights of these bands vary with the change of excitation frequencies. Possible explanation for different types of intensity variation of the two ring breathing vibrations has been provided.