Preparation of concealed marks with core-shell luminophores for customs security check system and application thereof

Preparation of concealed marks with core-shell luminosphores for customs security check system, characterized in that, comprising following steps:

• Step 1:
• preparing TiQ2:
• dripping TiCl4 into de-ionized water to be a mixture, dripping a solution containing ammonium sulfate and concentrated hydrochloric acid into the mixture, stirring at 15° C., wherein an ion concentration ratio is Ti4+:H+:SO42=15:1:30, heating the mixture at 10° C./min until 95° C. after fully mixing and dissolving, keeping for an hour, adding an appropriate amount of NH4OH solution, adjusting a pH value to be 5˜7, cooling to be consistent with ambient temperature, centrifuging for 10 min at 4500 r/min, cleaning a precipitate with de-ionized water and ethanol for three times and drying in a vacuum drying oven 80° C. for 10 h;
• Step 2:
• preparing Ag@TiO2 composite nanoparticles:
• immersing the TiO2 prepared in step 1 to a silver nitrate solution with a concentration of 0.001˜0.005 mol/L, irradiating with a high-voltage mercury lamp (100 W) for 3˜ 9 h, washing three times with high purity water and ethanol, drying and calcining for 3 h in a 450° C. muffle furnace for subsequent use;
• Step 3:
• preparing Ag@TiQ2@NaYF4:Yb3+, Er3+ luminescent nanoparticles:
• taking rare earth nitrate solution Y(NO3)3.6H2O, Yb (NO3)3.5H2O, Er (NO3)3.5H2O and mixing, doping Lanthanide ions with a concentration of a molar ratio of Y3+:Yb3+:Er3+=80:18:2, adding the Ag@TiO2 composite nanoparticles during mixing, adding a certain amount of NaF after mixing, mixing for 25 min on a magnetic mixer, heating in a water bath until 90° C., keeping for 2 h, cooling and centrifuging for 10 min at 8000 r/min, washing a precipitate with de-ionized water and ethanol for three times, putting subsided raw materials into a 60° C. vacuum drying oven to dry for 12 h and get the Ag@TiQ2@NaYF4:Yb3+, Er3+ luminescent nanoparticles,
• Step 4:
• making concealed luggage marks:
• dissolving Ag@TiO2@NaYF4:Yb3+, Er3+ nano-luminescence materials into an ethanol solution, spraying over a luggage tag with a spraying gun and forming a predetermined pattern;
• no marks will be reserved on the luggage in several seconds after solvent volatilization, so concealed marks are formed:
• wherein the application of the concealed marks with core-shell luminosphores for customs security check system characterized in that, comprising following steps:
• dissolving prepared Ag@TiQ2@NaYF4:Yb3+, Er3+ nano-luminescence materials into an ethanol solution, and spraying over the luggage tag with the spraying gun to form the predetermined pattern;
• in several seconds, no marks are visible on the luggage tag after solvent volatilization, so concealed marks are formed:
• and patterns of the concealed marks are categorized by species of contraband, and different patterns are made according to dangerous degrees of the same species of contraband so as to provide the concealed marks with hierarchical display of dangerous degrees,
• scanning tag information of check-in luggage with a security check system, and identifying an owner of the luggage;
• and conducting full-range facial recognition by the monitoring system deployed in a customs house or a station according to information of the suspect identified by the security check system, addressing the suspect and comparing with one who claims the luggage for double check;
• searching a position and a movement direction of the owner by facial recognition of a monitoring system and monitoring the same in real time;
• the owner cannot perceive any danger during claiming the luggage and becomes relaxed, and when the tag passes a security door equipped with a 980 nm laser, infrared luminescent materials on a surface of the tag will absorb near infrared light and irradiate visible light of the predetermined pattern;
• and
• the security door sends warning signals automatically after detecting irregularity, and security staff will bring the owner and the luggage to a security check room for further security check.