Inhomogeneous band shapes calculated for different relative displacements of potential minima of the ground and excited states, equal to (a), (b), and 1.0 (c). Boltzmann distribution of solvation energies is obtained for thermal energy at the glass point of 10% of the well depth in the ground state [, Eqs. (5) and (11)]. The potential well in the upper state is two times deeper than in the ground state . The spectra are obtained in a matrix with compressibility of PMMA, e.g., for the linear compression of 0.893 at (see Fig. 3).
Solvent shifts [Eq. (7)] and pressure shift coefficients [Eq. (13), ] calculated at the band maxima (a), and the widths of inhomogeneous bands at 0 and (b), plotted vs the relative shift of potential minima . A comparison of bandwidth at 0 and shows that at certain a narrowing is possible on compression. Other parameters are as in Fig. 1.
Pressure dependence of relative linear compression in poly(methyl methacrylate) (PMMA) and cellulose acetate [Eqs. (9) and (10), data from Ref. 42].
Calculated baric shifts of band maxima in PMMA [Eq. (6)] at different relative shifts of potential minima , ranging between (0.89) and (1.06) for , at (a) very high and (b) high pressures. The coordinate was converted to according to Fig. 3 and Eq. (9).
Relative baric shifts of absorption maxima at : (a) phenanthrene, anthracene, and 1,8-diphenyloctatetraene in poly(methyl methacrylate) (data from Refs. 7 and 8), (b) cyanine dyes thiatricarbocyanine, indodicarbocyanine, pseudoisocyanine, and oxacarbocyanine in cellulose acetate (Ref. 6). Absolute solvent shifts without pressure (Table I) are adjusted to . The shift is calculated (lines) at the displacements of potential minima equal to (0.89), (0.944), and 0.96, for .
Relative pressure broadening of absorption bands of phenanthrene and anthracene in PMMA at (data from Ref. 7). The broadening is calculated (open symbols) for the displacements of potential minima equal to (0.89), (0.944), and 0.97, with other parameters as in Fig. 1.
Absorption band properties of the chromophores in poly(methyl methacrylate) at . , absorption band maximum; 0–0 transition energy in vacuum, measured in a cold jet (, Refs. 25–28) or extrapolated from solvent shift data (Refs. 18 and 45); , solvent shift ; , pressure shift coefficient; FWHM, full width at half maximum; , slope of a plot of the band maxima versus the Lorentz-Lorenz function (polarizability) in liquids at (Refs. 18 and 45). Parameters referring to are shown in the brackets.
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