Fig. 1. Diagram of FTIR system

Fig. 2. Schematic diagram of TDS setup

Fig. 3. Frequency domain spectra of glucose samples

Fig. 4. FTIR absorption spectra of glucose samples with different ratios

Fig. 5. THz-TDS absorption spectra of glucose samples with different ratios

Fig. 6. Absorption spectra of fructose samples with different ratios

Fig. 7. Absorption spectra of galactose samples

Fig. 8. Absorption fitting results of galactose samples with different proportions at (a) 4.51 THz and (b) 8.71 THz

Fig. 9. (a) The absorption spectrum of F:Ga:PE=1:1:10 sample; (b) The absorption spectrum of F:G:PE=1:1:10 sample; (c) The absorption spectrum of Ga:G:PE=1:1:10 sample; (d) The absorption spectrum of F:Ga:G:PE=1:1:1:15 sample

Fig. 10. Fructose cell structure

Fig. 11. Galactose cell structure

Fig. 12. Comparison of fructose CASTEP simulation results with FTIR experimental results

Fig. 13. Comparison of CASTEP simulation results with FTIR test results for galactose