| Popis: |
Fingerprints are an important trace material evidence for police to identify criminal. Cadmium sulfide quantum dots (CdS QDs) are fluorescent-labeled nanomaterials that can be used to improve the clarity and resolution of fingerprints. In this study, thioglycollic acid (TGA) was successfully modified to CdS QDs using the in-situ radiation reduction method, and synthetic TGA-CdS QDs were combined with polyvinyl acetate (PVAc) to form a TGA-CdS QDs/PVAc gel fingerprint film for fingerprint development. The structure and properties of the TGA-CdS QDs were characterized and tested using Fourier transform infrared (FTIR) spectroscopy, fluorescence spectrum, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The effects of temperature, concentration of TGA-CdS QDs, pH, and mass fraction of the PVAc gel fingerprint film on fingerprint development were investigated. The results showed that a combination of 6 mg/mL TGA-CdS QDs solution with 20% PVAc gel fingerprint film at room temperature (25 ℃) and pH of 9.0 resulted in the clearest, most complete, and high-resolution fingerprint patterns of fluorescence display. The carboxylic acid group formed by TGA-CdS QDs in an alkaline solution completely combined with the amino acids, proteins, fats, urea, and other components of the fingerprint residue attached to the PVAc gel film. Under ultraviolet irradiation, the fingerprint lines were clearly displayed in the form of fluorescence. The fingerprint display method can be effectively used in criminal investigation. |
