Fig. 1. PL spectrum measurement system, target detection system and array scanning track
(a): PL spectrum measurement system; (b): Target detection system; (c): Array scanning track

Fig. 2. Emission spectra of near-infrared colloidal quantum dot arrays under different excitation light color
(a): The original spectra; (b): Spectra of different setection points

Fig. 3. PL spectra of NIR colloidal QD array and comparison of stability
(a): PL spectra of NIR colloidal QD array; (b): Comparison of PL spectra stability

Fig. 4. EMD decomposition and the PL spectra of NIR colloidal QD array
(a): The process of EMD decomposition; (b): The original PL spectra of NIR colloidal QD array;(c): The PL spectra of NIR colloidal QD array after EMD decomposition

Fig. 5. The flow diagram of reconstruction of target spectrum

Fig. 6. PL spectra of NIR colloidal QD array, PL spectra after passing through the chamber and PL spectra after absorbed by the ethanol gas
(a): PL spectra of NIR colloidal QD array; (b): PL spectra after passing through the chamber; (c): PL spectra after absorbed by the ethanol gas

Fig. 7. Reconstruction spectrum and standard spectrum
(a): Reconstruction spectrum with ethanol gas and background; (b): Reconstruction absorption spectrum of ethanol gas;(c): Standard spectrum of ethanol gas

Fig. 8. PL spectra of NIR colloidal QD array, PL spectra after passing through the chamber and PL spectra after absorbed by the sample
(a): PL spectra of NIR colloidal QD array; (b): PL spectra after passing through the chamber;(c): PL spectra after absorbed by the DMMP; (d): PL spectra of NIR colloidal QD array;(e): PL spectra after passing through the chamber; (f): PL spectra after absorbed by the CH₂Cl₂

Fig. 9. Reconstruction spectrum and standard spectrum
(a): Reconstruction spectrum with DMMP and background; (b): Reconstruction absorption spectrum of DMMP;(c): Standard spectrum of DMMP; (d): Reconstruction spectrum with CH₂Cl₂ and background;(e): Reconstruction absorption spectrum of CH₂Cl₂; (f): Standard spectrum of CH₂Cl₂