Dynamics of the time-resolved stimulated Raman scattering spectrum in
presence of transient vibronic inversion of population on the example of
optically excited trans-β-apo-8’-carotenal
Supporting information on raw data and base line subtraction
The Time-Resolved Femtosecond Stimulated Raman Scattering (TR-FSRS) data can
be superimposed on fluorescence1-3 and absorption3-5 like broad background. Thus, a spline fit
to the baseline is usually subtracted from the raw data.1-5 In our work a 4th order polynomial
was fit to the raw TR-FSRS data point in the vicinity of the Raman lines. Therefore, the
frequency regions below 1420 cm-1, between 1550 cm-1 and 1590 cm-1 and above 1890 cm-1
were used for the fit. The raw TR-FSRS data with polynomial fits and the spectra obtained by
subtraction of the latter ones are presented in Fig. 1 and 2 for twelve different time delays.
Figure 1. Examples of TR-FSRS raw spectra and baseline removal for selection of delays: -0.05 ps (a),
0.05 ps (b), 0.15 ps (c), 0.2 ps (d), 0.25 ps (e), 0.55 ps (f). For each delay the raw spectrum (black solid
curve) and a polynomial baseline fit (red dashed curve) are presented on the top plot, and the spectrum
after baseline subtraction is presented on the bottom plot. The negative signal close to 1775 cm-1 is
observed in figures b-e and zero crossing can be seen in figure f.
Figure 2. Examples of TR-FSRS raw spectra and baseline removal for selection of delays: 2 ps (a), 5
ps (b), 10 ps (c), 20 ps (d), 50 ps (e), 200 ps (f). For each delay the raw spectrum (black solid curve)
and a polynomial baseline fit (red dashed curve) are presented on the top plot, and the spectrum after
baseline subtraction is presented on the bottom plot. The decaying positive signal close to 1775 cm-1 is
observed in figures a-e.
References
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Phys. Chem. A 106, 6030–8 (2002).
2. P. Kukura, D. W. McCamant, P. H. Davis, and R. a. Mathies, "Vibrational structure of
the S2 (1Bu) excited state of diphenyloctatetraene observed by femtosecond stimulated
Raman spectroscopy," Chem. Phys. Lett. 382, 81–86 (2003).
3. S. Shim and R. A. Mathies, "Development of a tunable femtosecond stimulated raman
apparatus and its application to beta-carotene.," J. Phys. Chem. B 112, 4826–32 (2008).
4. D. W. McCamant, P. Kukura, and R. A. Mathies, "Femtosecond Time-Resolved
Stimulated Raman Spectroscopy: Application to the Ultrafast Internal Conversion in bCarotene †," J. Phys. Chem. A 107, 8208–8214 (2003).
5. P. Kukura, D. W. Mccamant, and R. A. Mathies, "Femtosecond Time-Resolved
Stimulated Raman Spectroscopy of the S2 (1Bu+) Excited State of b-Carotene," J. Phys.
Chem. A 108, 5921–5925 (2004).