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. Author manuscript; available in PMC: 2006 Dec 20.
Published in final edited form as: Rev Sci Instrum. 2004 Nov;75(11):4971–4980. doi: 10.1063/1.1807566

FIG. 6.

FIG. 6.

Femtosecond stimulated Raman spectra of the bacterial reaction center YFH mutant provided by Bocian and Chen (see Ref. 44). Shown in (a) is the absorption spectrum of the reaction center and the spectra of the Raman pump and probe pulses. The 800 nm Raman pump produces a large transient bleach of the P band and an increase in the transmitted intensity of the probe, causing the large baseline offset in the gain spectrum (b). When a polynomial baseline is subtracted, the resultant Raman gain spectrum (c) contains a very high systematic noise level. To remove this noise, a second gain spectrum is collected in which the Raman pump has been shifted to 799 nm. Taking the difference of the 799 and 800 nm Raman gain spectra removes the baseline and the systematic noise to produce the shot-noise-limited SERDS (d) (see Ref. 45). From the SERDS spectrum, the Raman spectrum can be reconstructed (e) by integration or by fitting to a predetermined peak shape.