(a) and (b) Normal incidence absorption spectra of a few microns thick crystal as taken at when impinging on the accessible face with the electric field of the incident light along, respectively, the and the axis. In the energy range where saturation effects are dominant, the -polarized spectrum is omitted. (c) -polarized absorption spectrum of a few hundreds nanometer thick crystal as taken at with -polarized incident light. Inset: the spectrum as taken in a wider energy range.
Temperature dependence of the 0-0 absorbance peak and its first replica of origin for three different single crystals. Note that the absorbance axis reports absolute values, but, in order to avoid the superposition of the spectra, each spectrum has been shifted to each other by a fixed amount.
Temperature dependence of the lowest energy absorbance peak in the -polarized spectra and few replicas for three different single crystals. Each spectrum has been shifted for viewing purposes.
Continuous lines represent the energies of resonance of the vibron states as a function of the intermolecular electronic interaction strength for the Davydov component. The dotted line represents the dependence on of the relative lineshift between the 0-0 state and its first replica.
Temperature dependence of the relative lineshift between the 0-0 transition and its first replica for samples A (▴), B (◆), and C (●). The intensity ratio as measured at between the same two structures is also indicated for the three samples. The theoretical value of is also reported.
Measured width at half maximum of the 0-0 (full marker) and (empty marker) absorption peak as a function of temperature for samples A (▴), B (◆), and C (●). The continuous and dotted lines represent the fitting with Eq. (3) of the measured data relative to the sample (B) for and polarizations, respectively.
Measured width at half maximum of the first replica in (full marker) and -polarized (empty marker) absorption spectra as a function of temperature for samples A (▴), B (◆), and C (●). The continuous and dotted lines represent the linear fitting with Eq. (3) of the measured data correspondent to sample (C) for and polarizations, respectively.
Lineshape and position of the 0-0 peak in the spectra collected at on the three different samples and relative lineshift and intensity ratio , between the 0-0 line and its first replica as deduced from the spectra shown in Fig. 2. In the last columns of the table the residual linewidth of the first two absorption peaks as measured at on the three samples for both polarizations is reported. Note that for the first replica of origin relative to samples. A and B is not reported since it is rather difficult to be determined due to a low signal to noise ratio. The 0-0 peak position, the relative lineshift, and the residual linewidth are reported in .
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