Stationary absorption spectra of BSP in different solvents with the magnified part (in the inset) in the long-wavelength range.
Stationary absorption spectra (solid line), fluorescence spectra (dashed line, excitation at ), and excitation spectra (dotted line, emission observed at ) of BSP in trifluoroacetic acid.
Stationary fluorescence spectra of BSP in various solvents. For TFE the spectra with two different excitations are shown.
The excitation spectra (solid line) of BSP in EtOH (a) and TFE (b), normalized at the long-wavelength band to the relative intensity of the absorbed light (dotted line). The inset in (a) shows the magnified spectrum of the long-wavelength part in EtOH, while the inset in (b) shows the excitation spectrum (solid line) in TFE when normalized at the short-wavelength absorption band (dotted line). The observation wavelength is .
Transient absorption spectra of BSP in EtOH (a) and HX (b) for selected time delays between the pump and probe pulses.
The comparison of the kinetic curves and the fits at the probe wavelength of for BSP and (normalized to the BSP signal) in EtOH. The values of the fitted parameters (one- or three-exponential functions convoluted with the instrumental function) are the following. BSP: , ; , ; , ; : , ; . Inset: transient absorption spectra of in ACN for selected time delays between the pump and probe pulses.
Examples of the kinetic curves of the transient absorption signals for BSP in TFE, and the fits for the excitation wavelengths (a) and (b). The insets show the same kinetic curves and the fits in the short time scale. The values of the fitted parameters (one-, two-, and three exponential functions convoluted with the instrumental function) are the following. (a) Excitation: ; probe wavelengths: (circles): , ; , ; , , ; (squares): , ; , ; , ; ; (triangles): , ; , ; . (b) Excitation: ; probe wavelengths: (circles): , ; ; (squares): , ; , ; , ; ; (triangles): , ; , , .
The comparison of the transient absorption spectra of BSP in TFE taken after the excitation at 390 and . The spectrum for is normalized to the spectrum for by multiplying it by the factor of 1.7. The long-wavelength stationary absorption band of the keto tautomer (keto GSD) and the effect of its subtraction from the experimental spectrum for are also shown.
The ratio of the stationary absorbance of the keto form of BSP to the absorbance of the enol form as a function of solvatochromic parameters (, , and ) of selected solvents (see text for details).
The spectroscopic parameters of BSP in selected solvents: the maximum of fluorescence band , the fluorescence quantum yield , and the lifetime of the state of the keto tautomer . The uncertainty of the determination is , while the error of is .
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