Application of metavanadate

Abstract

The invention discloses application of metavanadate, and belongs to the technical field of fingerprint detection. And the metavanadate is cesium metavanadate or rubidium metavanadate and is used for displaying fingerprints. The metavanadate is excited by near ultraviolet light. The invention relates to a fingerprint development method, which adopts cesium metavanadate or rubidium metavanadate, and realizes fingerprint development through a powder scattering and brushing method, a direct brushing method, a powder scattering and shaking method or a powder scattering and blowing method. The preparation method comprises the following steps: dispersing carbonate and vanadium pentoxide in methanol to obtain a suspension; grinding and drying the suspension to obtain a mixture; and calcining the mixture to obtain the metavanadate fluorescent material. The carbonate comprises at least one of cesium carbonate and rubidium carbonate, and the metavanadate comprises at least one of cesium metavanadate and rubidium metavanadate.

Description

Technical Field

[0001] The invention relates to the field of detection technology, and in particular to an application of metavanadate. Background Art

[0002] Handprints are different for each person, remain basically unchanged throughout life, and leave marks on objects. Therefore, they can be used to identify people and have been widely used in areas such as access control, attendance, and privacy protection. The traces left on the surface of an object when a handprint touches an object are called handprints. Handprints are an important physical evidence in forensic science and are known as the "first of evidence." By looking for the person who left the handprints, you can find people related to the case, provide clues for determining the scope of investigation, and clarify the facts of the case, providing evidence materials for solving the case and litigation. Most of the handprints left at the scene are latent handprints that are invisible to the naked eye. Using appropriate visualization methods to clearly and completely reveal the latent handprints plays a vital role in solving the case.

[0003] Powder development is one of the commonly used development methods at the scene. It is easy to operate, highly efficient and widely used. The development principle is to use the physical adhesion and electrostatic attraction between the powder and the fingerprint residue. Commonly used development powders include "gold powder", "silver powder", magnetic powder and fluorescent powder. Although "gold powder", "silver powder" and magnetic powder have strong adsorption force, they are greatly affected by the background color and pattern of the object when used, resulting in low contrast and poor sensitivity of the displayed fingerprint. Fluorescent powder can produce fluorescence under the irradiation of a suitable excitation light source. When developing latent fingerprints, the strong fluorescence can significantly enhance the contrast between the fingerprint and the object, effectively reduce the interference of the background, and has a higher sensitivity. Compared with traditional powders, the advantages are very obvious and have attracted the attention of forensic scientists.

[0004] At present, the fluorescent powders used for fingerprint visualization include fluorescent dyes, cadmium quantum dots, silicon-based nano fluorescent materials, aggregation-induced luminescence materials and rare earth fluorescent materials. Fluorescent dyes have organic components and will gradually degenerate after fingerprint visualization, making them difficult to retain. Cadmium quantum dots, silicon-based nano fluorescent materials, aggregation-induced luminescence materials and rare earth fluorescent materials mostly use a small particle suspension method to visualize fingerprints. This visualization method has many operating steps and low efficiency, and is not suitable for use at actual crime scenes. In addition, the preparation process of these materials is complicated, the process is cumbersome, the cost is high, and they cannot be mass-produced. Therefore, it is necessary to explore new fluorescent visualization materials and visualization methods. Summary of the invention

[0005] The present invention aims to provide a new fluorescent material and method for revealing the latent handprint. The present invention provides a metavanadate application, wherein the metavanadate fluorescent material can be combined with a latent handprint forming material through physical adhesion and electrostatic adsorption; under the irradiation of a light source of a certain wavelength, the metavanadate fluorescent material generates fluorescence, forming a sharp contrast with the background object, thereby revealing the latent handprint.

[0006] The present invention is achieved through the following technical solutions:

[0007] An application of metavanadate in the field of fingerprint detection technology;

[0008] Metavanadate is cesium metavanadate or rubidium metavanadate, used for mudra manifestation.

[0009] Further optionally, near ultraviolet light is used to excite the metavanadate.

[0010] A method for revealing fingerprints adopts cesium metavanadate or rubidium metavanadate to realize fingerprint revealing through powdering and brushing method, direct brushing method, powdering and shaking method or powdering and blowing method.

[0011] The present invention is particularly suitable for sweat latent fingerprints and oil latent fingerprints on non-permeable objects, semi-permeable objects and permeable objects (such as paper).

[0012] The handprint revealing method provided by the present invention is particularly suitable for revealing latent handprints.

[0013] Further optionally, the powdering and brushing method comprises the steps of:

[0014] Use a brush to dip into the fluorescent material powder and sprinkle it on the subject's handprint;

[0015] After a thin layer of powder is deposited on the surface of the object, use the brush to brush it. When you see the outline of the handprint, brush it along the direction of the handprint lines.

[0016] Remove excess fluorescent material powder;

[0017] The excitation light source is irradiated onto the area where the handprint appears, visible light is generated on the surface of the handprint, and the handprint image is captured using a digital camera.

[0018] The excitation light source preferably has a wavelength of 254 nm to 400 nm.

[0019] A method for preparing metavanadate, wherein the prepared material is used in the field of fingerprint detection, and the preparation method comprises the steps of:

[0020] dispersing carbonate and vanadium pentoxide in methanol to obtain a suspension;

[0021] Grinding and drying the suspension to obtain a mixture;

[0022] calcining the mixture to obtain a metavanadate fluorescent material;

[0023] The carbonate includes at least one of cesium carbonate and rubidium carbonate, and the metavanadate includes at least one of cesium metavanadate and rubidium metavanadate.

[0024] The metavanadate fluorescent material provided by the present invention can be combined with the material forming the latent handprint through physical adhesion and electrostatic adsorption; under the irradiation of a light source of a certain wavelength, the metavanadate fluorescent material generates fluorescence, forming a sharp contrast with the background object, thus making the latent handprint appear.

[0025] Further optionally, the mass ratio of the carbonate to methanol is no more than 1:5.

[0026] Further optionally,

[0027] If cesium carbonate is used as carbonate, the mass ratio of vanadium pentoxide to carbonate is 1:1.8-2.3;

[0028] If rubidium carbonate is used as the carbonate, the mass ratio of vanadium pentoxide to carbonate is 1:1.3-1.7.

[0029] Further optionally, the calcination temperature is 300° C. to 550° C., and the calcination holding time is 3 h to 24 h.

[0030] Further optionally, when preparing the suspension:

[0031] Firstly, the carbonate is dispersed in methanol to obtain a methanol solution of the carbonate;

[0032] Vanadium pentoxide is then added and mixed to obtain a suspension.

[0033] The present invention has the following advantages and beneficial effects:

[0034] 1. The present invention provides an application of metavanadate, a metavanadate fluorescent material, which has excellent luminescence performance, suitable adsorption capacity, and the advantages of high contrast, high sensitivity and selectivity, and low background interference in revealing latent handprints; the luminescence color of the metavanadate fluorescent material is close to white light, and it also has a good revealing effect on objects with fluorescent effects. Compared with other fluorescent materials, it has great advantages and provides a new idea for handprint revealing technology.

[0035] 2. The metavanadate of the present invention can be used for latent fingerprint detection, and is suitable for sweat latent fingerprints and oil latent fingerprints on non-permeable objects, semi-permeable objects and permeable objects. The development method is simple to operate, and can be developed by powdering and brushing, direct brushing, powdering and shaking, powdering and blowing.

[0036] 3. The preparation method of metavanadate provided by the present invention is simple and has a low calcination temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0038] Figure 1 This is the XRD pattern of the fluorescent material provided in Example 1.

[0039] Figure 2 This is the SEM image of the fluorescent material provided in Example 1.

[0040] Figure 3 The excitation spectrum and emission spectrum of the fluorescent material provided in Example 1.

[0041] Figure 4 This is a diagram showing the effect of latent fingerprints revealed by the fluorescent material provided in Example 1.

[0042] Figure 5 This is the XRD pattern of the fluorescent material provided in Example 2.

[0043] Figure 6 This is the SEM image of the fluorescent material provided in Example 2.

[0044] Figure 7 The excitation spectrum and emission spectrum of the fluorescent material provided in Example 2.

[0045] Figure 8 This is a diagram showing the effect of latent fingerprints revealed by the fluorescent material provided in Example 2. DETAILED DESCRIPTION

[0046] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0047] Example 1

[0048] This embodiment provides a new type of fluorescent material, cesium metavanadate fluorescent material, and the specific preparation method is as follows:

[0049] Step 1: dispersing 6.5 g of cesium carbonate in 50 ml of methanol to obtain a cesium carbonate methanol solution;

[0050] Step 2: 3.6 g of vanadium pentoxide and cesium carbonate methanol solution are mixed to obtain a suspension, and then the obtained suspension is fully ground and dried to obtain a mixture;

[0051] Step 3: calcine the mixture at 300°C for 3 hours to obtain cesium metavanadate phosphor powder.

[0052] 1. Phase analysis

[0053] The solid phase reaction product is subjected to phase analysis, such as Figure 1 As shown, its XRD pattern corresponds to that of CsVO3 (JCPDS70-0680) with an orthorhombic structure, and there is no obvious impurity peak, indicating that the synthesized cesium metavanadate is a pure phase.

[0054] 2. Morphology characterization

[0055] The morphology of cesium metavanadate is as follows Figure 2 As shown, it is a block structure.

[0056] 3. Fluorescence spectrum

[0057] The excitation and emission spectra of cesium metavanadate are as follows Figure 3 The peak of the excitation spectrum of cesium metavanadate is near 366nm, which is a near-ultraviolet excited fluorescent material. The peak of the emission spectrum is near 518nm, which is basically consistent with the visible range of human eyes, and the emission bandwidth is large, covering the entire visible light band.

[0058] 4. Latent fingerprints revealing methods and effects

[0059] (1) Latent fingerprints revealing method:

[0060] Use a fingerprint brush to dip cesium metavanadate fluorescent powder and sprinkle it on the latent fingerprint;

[0061] After a thin layer of powder is deposited on the surface of the object (glass, plastic bags, tiles, paper, bookshelves and packaging bags), use a clean brush to gently brush it. After you see the outline of the handprint, brush it along the direction of the handprint lines.

[0062] Then, the excess cesium metavanadate fluorescent powder is removed;

[0063] Finally, the 254nm excitation light is directly irradiated onto the area where the handprint appears, bright visible light is generated on the surface of the handprint, and then the handprint image is captured with a digital camera.

[0064] (2) Latent fingerprint display effect:

[0065] like Figure 4 As shown, cesium metavanadate fluorescent material has a good latent fingerprint revealing effect on non-permeable object glass, plastic bags, semi-permeable object tiles and permeable object paper. The revealed fingerprint lines are clear and coherent, with high contrast and selectivity, obvious details, easy to observe and analyze, and meet the requirements of inspection and identification.

[0066] At the same time, the latent fingerprints revealed by the cesium metavanadate fluorescent material on patterned bookshelves and packaging bags are also clear and complete, effectively suppressing the interference of the background. The primary (line type) and secondary features (detail features) of the fingerprints can be obtained from the fingerprint images, which meets the requirements of inspection and identification.

[0067] Example 2

[0068] This embodiment provides a new type of fluorescent material, rubidium metavanadate fluorescent material, and the specific preparation method is as follows:

[0069] Step 1: dispersing 4.6 g of rubidium carbonate in 50 ml of methanol to obtain a rubidium carbonate methanol solution;

[0070] Step 2: 3.3 g of vanadium pentoxide and rubidium carbonate methanol solution are mixed to obtain a suspension, and then the obtained suspension is fully ground and dried to obtain a mixture;

[0071] Step 3: calcine the mixture at 400°C for 12 hours to obtain rubidium metavanadate phosphor.

[0072] 1. Phase analysis

[0073] The solid phase reaction product is subjected to physical analysis, such as Figure 5 As shown, its XRD pattern corresponds to that of RbVO3 (JCPDS36-1213) with an orthorhombic structure, and there is no obvious impurity peak, indicating that the synthesized rubidium metavanadate is a pure phase.

[0074] 2. Morphology characterization

[0075] The morphology of rubidium metavanadate is as follows Figure 6 As shown, it is a spherical structure.

[0076] 3. Fluorescence spectrum

[0077] The excitation and emission spectra of rubidium metavanadate are as follows Figure 7 The peak of the excitation spectrum of rubidium metavanadate is near 366nm, which is a near-ultraviolet excited fluorescent material. The peak of the emission spectrum is near 519nm, which is basically consistent with the visible range of human eyes, and the emission bandwidth is large, covering the entire visible light band.

[0078] 4. Latent fingerprints revealing methods and effects

[0079] (1) Latent fingerprints revealing method:

[0080] Use a fingerprint brush to dip into cesium metavanadate fluorescent powder and sprinkle it on the fingerprint;

[0081] After a thin layer of powder is deposited on the surface of the object (aluminum foil, plastic bag, tile, paper, packaging box and packaging bag), use a clean brush to gently brush it. After seeing the outline of the handprint, brush it along the direction of the handprint line;

[0082] Then, the excess cesium metavanadate fluorescent powder is removed;

[0083] Finally, the 254nm excitation light is directly irradiated onto the area where the handprint appears, bright visible light is generated on the surface of the handprint, and then the handprint image is captured with a digital camera.

[0084] (2) Latent fingerprint display effect:

[0085] like Figure 8 As shown, the rubidium metavanadate fluorescent material has a good latent fingerprint revealing effect on non-permeable objects such as aluminum foil and plastic bags, semi-permeable objects such as ceramic tiles and permeable objects such as paper. The revealed fingerprint lines are clear and continuous, with high contrast and obvious details, which are easy to observe and analyze, and meet the requirements of inspection and identification.

[0086] At the same time, the latent fingerprints revealed by the rubidium metavanadate fluorescent material on patterned boxes and bags are also clear and complete, effectively suppressing the interference of the background. The primary (line type) and secondary features (detail features) of the fingerprints can be obtained from the fingerprint image, which meets the requirements of inspection and identification.

[0087] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An application of metavanadate, characterized in that: Used in the field of fingerprint detection technology; Metavanadate is cesium metavanadate or rubidium metavanadate, used for mudra manifestation.

2. The use of a metavanadate according to claim 1, characterized in that: Near-ultraviolet light is used to excite metavanadate.

3. A method for displaying handprints, characterized in that: Using cesium metavanadate or rubidium metavanadate, fingerprint visualization is achieved through powdering and brushing method, direct brushing method, powdering and shaking method or powdering and blowing method.

4. A handprint display method according to claim 3, characterized in that: The powdering and brushing method comprises the following steps: Use a brush to dip into the fluorescent material powder and sprinkle it on the subject's handprint; After a thin layer of powder is deposited on the surface of the object, use the brush to brush it. When you see the outline of the handprint, brush it along the direction of the handprint lines. Remove excess fluorescent material powder; The excitation light source is irradiated onto the area where the handprint appears, visible light is generated on the surface of the handprint, and the handprint image is captured using a digital camera.

5. A method for preparing metavanadate, characterized in that: The prepared material is used in the field of handprint detection, and the preparation comprises the following steps: dispersing carbonate and vanadium pentoxide in methanol to obtain a suspension; Grinding and drying the suspension to obtain a mixture; calcining the mixture to obtain a metavanadate fluorescent material; The carbonate includes at least one of cesium carbonate and rubidium carbonate, and the metavanadate includes at least one of cesium metavanadate and rubidium metavanadate.

6. The method for preparing metavanadate according to claim 5, characterized in that: The mass ratio of the carbonate to methanol is no more than 1:

5.

7. The method for preparing metavanadate according to claim 5, characterized in that: If cesium carbonate is used as the carbonate, the mass ratio of vanadium pentoxide to carbonate is 1:1.8-2.

3.

8. The method for preparing metavanadate according to claim 5, characterized in that: If rubidium carbonate is used as the carbonate, the mass ratio of vanadium pentoxide to carbonate is 1:1.3-1.

7.

9. The method for preparing metavanadate according to claim 5, characterized in that: The calcination temperature is 300°C to 550°C, and the calcination holding time is 3h to 24h.

10. The method for preparing metavanadate according to claim 5, characterized in that: When preparing the suspension: Firstly, the carbonate is dispersed in methanol to obtain a methanol solution of the carbonate; Vanadium pentoxide is then added and mixed to obtain a suspension.

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