Fig. 1. 3D fluorescence spectrum of ten-year liquor

Fig. 2. Signals of wavelet decomposition
(a): Approximate signal; (b): Detail signal

Fig. 3. Derivative spectrum of vintage liquor (excitation wavelength: 200 nm)
(a): First derivative spectrum; (b): Second derivative spectrum

Fig. 4. Diagram of effective signal intensity

Fig. 5. The correlation between concentration and original 3D spectra

Fig. 6. The correlation between derivative spectra and concentration
(a): First order derivative spectra;(b): Two order derivative spectra

Fig. 7. The correlation between wavelet decomposition spectra and concentration
(a): Detail signal in the 3rd layer;(b): Detail signal In the 4th layer

Fig. 8. Scatter diagram of second derivative spectral modeling results

Fig. 9. The curve of information density distribution of spectrum