The red region of the X- and Y-polarized spectra obtained from the measurement of linear dichroism of chlorophyll a and pheophytin a oriented in a liquid crystal-1 has been reexamined. A combination of resolution enhancement of the spectra involving their Fourier transformation and manipulation in the Fourier domain, and deconvolution into Gaussian bands on the wavenumber scale has produced results conforming to previous conclusions that place the origin of the Qx transition in chlorophyll a some 800-900 cm-1 to the blue relative to the origin of the Qy transition. In pheophytin a, however, the separation between
the Qx and QY bands is much larger, about 3600 cm-l. The results also confirm previous reports of an angle near 70� between the transition moment directions of the Qy transitions and the molecular X-axis for both chlorophyll a and pheophytin a. The resolved vibronic bands in the case of the Qy transition of chlorophyll a, at least, have their counterparts in both solution spectra and high-resolution low-temperature fluorescence excitation spectra.
