Compensation-alternating acquisition strategy for fluorescence residual suppression and stability enhancement in...

Raman spectroscopy often encounters strong fluorescence background interference in practical applications. Although Shifted-Excitation Raman Difference Spectroscopy (SERDS) is effective for fluorescence suppression, traditional acquisition modes tend to introduce significant fluorescence residuals in direct difference spectra. These residuals arise from dynamic fluorescence decay processes such as photobleaching and thermal effects and can severely compromise the stability of reconstructed Raman spectra. Current solutions predominantly focus on algorithmic correction after the residuals have been generated, with limited strategies to suppress them at the data acquisition stage. To address this limitation, this paper proposes a novel Compensation-Alternating Acquisition Mode (CompAAM). Without extending the total exposure duration time, this method reduces background differences caused by asynchronous fluorescence attenuation by optimizing the excitation timing and implementing an exposure compensation mechanism with the dual-wavelength laser. Using highly fluorescent plastic samples, the study systematically evaluated three acquisition modes: the conventional Wavelength-Alternating Acquisition Mode (WAAM), the Count-Alternating Acquisition Mode (CAAM), and the proposed CompAAM. Experimental results demonstrate that CompAAM most effectively suppresses fluorescence residuals in difference spectra. In terms of spectral stability, the relative standard deviation (RSD) of characteristic peak intensities under this mode can be reduced to 0.97%-1.43%, significantly lower than those observed under the Wavelength-Alternating Acquisition Mode (5.85%-8.60%) and the Count-Alternating Acquisition Mode (2.10%-4.21%). This study confirms that the proposed CompAAM can substantially enhance the reconstruction quality and the stability of differential Raman spectra right from the measurement source, and provides an effective strategy for the reliable analysis of samples with strong fluorescence backgrounds.