CN115746836A - Preparation method of nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder - Google Patents
Preparation method of nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder Download PDFInfo
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
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Abstract
A preparation method of nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder belongs to the technical field of fingerprint detection, and comprises the following steps: preparing nitrogen-gadolinium doped carbon dots which are brown under sunlight, modifying the carbon dots on the surface of a core which is diatomite to prepare a yellow nitrogen-gadolinium doped carbon dot-diatomite nano composite material, and absorbing and combining the prepared nitrogen-gadolinium doped carbon dots through a diatomite hierarchical pore structure, so that a fluorescence quenching phenomenon caused by carbon dot agglomeration is eliminated, and the fluorescence intensity is obviously enhanced; and a 365nm or 450nm light source obliquely irradiates on the fingerprint lines after the fingerprint lines are displayed, and a digital camera or a microscope is used for photographing and imaging, so that the visible fingerprint is green and luminous. After being irradiated by a light source, the latent fingerprints on various substrate materials can be quickly, simply and conveniently imaged without background interference.
Description
Technical Field
The invention belongs to the technical field of fingerprint detection, and particularly relates to a preparation method of nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder.
Background
The fingerprints have the characteristics of different people, no change for the whole life, trace after touching objects and the like, and have the reputation of the king of evidence. One of the important bases for confirming crimes and discriminating criminal suspects in judicial practice activities is the most effective weapon and means for fighting criminals. The fingerprints are basically invisible in on-site investigation and are potential traces, the traditional display methods comprise a powder display method, a 502 display method, an iodine fumigation method, an indetrione method, a silver nitrate method and the like, and the traditional display powder has the characteristics of fine particles and easiness in floating and is easy to cause serious harm to the health of professional technicians. The research on the cheap, non-toxic and pollution-free display powder is always a research hotspot of professional technicians.
Rare earth oxide (Y) 2 O 3 、Gd 2 O 3 And CeO 2 ) Due to the unique optical properties and good stability, the potential applications in multiple fields are attracting much attention. Wherein criminal technicians use their stable fluorescent properties as one of the fingerprint revealing powders. However, as a strategic resource, rare earth, a multifunctional material, is not suitable for large-scale fingerprint visualization.
The nano material is also called as ultramicro particle material, and refers to particles with the size of 1-100 nm. Has unique physical and chemical properties due to unique size effect. In order to eliminate the influence brought by background color in the showing process, the problem is effectively solved by the nano fluorescent powder, but the problems of cost and particle suspension are not solved all the time.
Carbon dots refer to carbon particles having fluorescent properties with a size of less than 20 nm. Having a single-layer or multi-layer graphite structure, and may also be polymer-based aggregate particles. The fluorescent material has the unique optical properties of high fluorescence intensity, adjustable emission wavelength, wide excitation wavelength range and the like, and simultaneously, the carbon dots have low preparation cost and are very easy to obtain in life, and common carbon-containing organic matters such as cereal grass, straws and the like can be used. The research on the luminescent nano-particles represents a new stage of the research on the luminescent nano-particles.
In long-term practice and application, it is found that carbon dots with different emission wavelengths and fluorescence intensities can be prepared by optimizing test conditions such as controlling heating time, raw material selection, raw material composition and proportion, and the like, and the excellent fluorescence property of the carbon dots is utilized to replace the traditional fluorescent powder, so that the carbon dots have great tension when being used for showing potential fingerprints in criminal science technology. However, the aggregation of the nano carbon dots induces the phenomenon of fluorescence quenching, so that the further application of the nano carbon dots in fingerprint visualization is limited.
Therefore, in order to overcome the defects of carbon dots, a surface carbon dot composite material with stable surface morphology, uniform particle dispersion and excellent luminescence property needs to be developed, so that the surface carbon dot composite material is systematically used for identification imaging, inspection and identification of latent fingerprints of sweat in an actual working environment. The invention provides a method for preparing a nitrogen-gadolinium doped carbon dot-diatomite nanocomposite by taking organic fruit acid as a carbon source, ethanolamine as a nitrogen source, gd element as a modifier and diatomite as a carrier through a microwave synthesis technology, which avoids the agglomeration of carbon dot particles, realizes solid fluorescence, improves the stability and the intensity of emitted fluorescence by utilizing the unique optical property of Gd, and shows the practical application value in the fingerprint development direction.
Disclosure of Invention
The invention aims to provide a preparation method and a use method of a nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder material for latent fingerprint development, which are simple to operate, efficient, convenient, safe, rapid and wide in universality. The invention is characterized in that the nitrogen-gadolinium doped carbon quantum dot and diatomite nano composite powder is synthesized by adopting a one-step microwave method for the first time, gd is doped in the carbon quantum dot by virtue of the excellent luminescence property of element Gd, so that the fluorescence enhancement effect is achieved, the nitrogen-gadolinium doped carbon dot adsorbed on the surface of the diatomite can generate a continuous, stable and efficient solid state luminescence effect under the excitation of a light source, and the on-site fingerprint can be quickly displayed.
A preparation method of nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder specifically comprises the following steps:
weighing carbon source and nitrogen source according to a certain proportion, adding distilled water, stirring uniformly and completely dissolving, and then weighing GdCl according to a certain proportion 3 Adding the mixture into the solution, transferring the mixed solution into a 700W microwave oven for microwave heating for 5-60 min, naturally cooling the colorless solution to room temperature, filtering to remove insoluble substances, dialyzing and purifying to obtain carbon-doped dots, and drying at 100-110 ℃ to obtain brown nitrogen-gadolinium doped carbon dots;
dissolving the prepared nitrogen-gadolinium doped carbon dots in distilled water, adding matrix diatomite according to the mass ratio of 1.
The preparation method of the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder comprises the following steps:
the carbon source is selected from glycolic acid, lactic acid, malic acid, and mandelic acid.
The nitrogen source is selected from monoethanolamine, diethanolamine and triethanolamine.
The mass ratio of the carbon source, the nitrogen source and the gadolinium chloride is (1-10) to (1-5) to (1-2).
The loading capacity of the prepared carbon dots is 4% -5%, the particle size of the prepared composite material is 2-20 microns, and green fluorescence can be seen under the irradiation of 365nm or 450nm light.
The nitrogen-gadolinium doped carbon dot-diatomite nano composite material prepared by the invention has the characteristic of green fluorescence, has uniform particle size, is stable between 2 and 20 micrometers, and is used for latent fingerprint display imaging.
The application of the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder in the aspect of latent fingerprint imaging can adopt a classical powder method, and the specific steps are as follows:
step 1: preparation of latent oil-sweat mixed fingerprints
And pressing the fingerprint on the surface of the carrier, and transferring the oily sweat mixture on the finger to the surface of the carrier to form a fingerprint latent print so as to obtain an oily sweat latent fingerprint sample.
Step 2: powder display method for displaying finger print
Dipping a small amount of prepared nanocomposite developing powder by using a fingerprint brush, brushing the nano composite developing powder on the latent fingerprints left on the surface of the carrier, shaking off redundant appearing powder after the lines of the fingerprints are found, and continuously brushing the redundant powder along the flowing direction of the fingerprint lines by using the fingerprint brush until the lines of the fingerprint sample are clearly shown.
And step 3: extracting fingerprints
And a 365nm or 450nm light source is selected to obliquely irradiate on the fingerprint lines after the latent fingerprint is displayed, and a digital camera or a microscope is used for photographing and imaging, so that the visible fingerprint is green and luminous, and the aim of displaying the latent fingerprint by fluorescence is fulfilled. A variety of feature information is visible from the fingerprint image, including level 2 and level 3 features of the fingerprint.
The latent fingerprint carrier comprises glass, metal, paper, plastic, food packaging materials, leather and ceramics.
In the existing research, fingerprint development is mainly applied to fingerprint detection in two forms of liquid dispersed carbon dots and solid luminescent carbon dots. The stability of the liquid dispersed carbon dot aqueous solution is poor, and the application of the aqueous solution to glass, plastics and other substrates is very limited. The solid-state light-emitting carbon dots are easy to cause fluorescence quenching due to carbon dot aggregation, and researches find that the carbon dots are dispersed by using a matrix material to keep the fluorescence performance of the carbon dots become a hot point of research. Although some researchers have tried to disperse carbon dots in polymer gel, the method is complicated; researchers also synthesize solid-state fluorescent carbon dots by a microwave method, but the types and the number of active groups are limited, or the luminous intensity is weak, so that the solid-state fluorescent carbon dots are not easily combined with the surface grains of the fingerprint, the fluorescence resolution is poor during fingerprint development, and secondary and tertiary information of the fingerprint cannot be obtained. Meanwhile, the blue background interference of a plurality of objects also causes the low significance and contrast of fingerprint development, and limits the further application in the technical field of criminal science. The carbon dot composite powder with stable fluorescence characteristic, good biocompatibility and good bonding capacity is synthesized to carry out fingerprint development, and the requirement of the public security combat is met.
In order to solve the problem of limited conditions of solid-state luminescence, a proper carbon dot synthesis control route (temperature, time and method) and a carbon source, a nitrogen source and gadolinium chloride proportion are selected, spherical porous diatomite is selected as a matrix material, after the carbon dots are synthesized by microwaves, the carbon dots are dispersed in the matrix material diatomite by a hydrothermal synthesis method, rich hydroxyl groups and amino groups on the surfaces of the carbon dots are physically embedded into the surface of the matrix material diatomite, the distance between the carbon dot particles is increased by passing through a porous spherical structure of the diatomite and the electrostatic action between the carbon dots, particle agglomeration is avoided, composite light of photo-generated electrons and holes is weakened, and the quantum yield is improved. Further changing the physical appearance of the composite material and the absorption characteristic of an absorption peak, and realizing the rapid response fingerprint development. The surface of the carbon dots is functionalized by optimizing a synthesis route, and the synthetic material has the fingerprint development characteristics of stable luminescence, good biocompatibility and strong adhesion.
The invention has the following advantages:
(1) The nitrogen-gadolinium doped carbon dot-diatomite nanocomposite disclosed by the invention has the advantages of simple preparation method, low cost, high yield, stable performance, environmental friendliness and the like;
(2) The developing method disclosed by the invention is simple to operate, high in display efficiency and suitable for popularization.
(3) According to the invention, the nitrogen-gadolinium doped carbon dots are used as fluorescent markers to show potential fingerprints, and the nitrogen-gadolinium doped carbon dots are uniformly dispersed in diatomite through electrostatic or Van der Waals effect, so that agglomeration of doped carbon dot nanoparticles is avoided, and the nano composite material with higher fluorescence quantum yield, larger absorption coefficient, stronger fluorescence brightness and more stable combination is generated on the surface of the diatomite.
(4) The nitrogen-gadolinium doped carbon dot-diatomite nano composite material provided by the invention is directly applied to various base materials in a particle form, such as latent fingerprints on the surfaces of common substances of glass, metal, paper, plastic, leather, ceramic and the like, and can overcome the interference of the background of the base material.
(5) The method overcomes the fluorescence quenching condition caused by the agglomeration of the carbon dots in the drying process of the carbon dot solution, the synthesized carbon dots are uniformly dispersed on the surface of the matrix to form a stable composite material, and each detail and various characteristic information of the latent fingerprint can be clearly reproduced due to the affinity of the carbon dot-diatomite nanocomposite material to the fingerprint residues.
Drawings
FIG. 1 is a transmission electron microscope image of carbon dots prepared in example 1 of the present invention.
Fig. 2 is a fluorescence spectrum of the nitrogen gadolinium-doped carbon dot-diatomite nanocomposite material prepared in example 1 of the present invention.
FIG. 3 shows the powder comparison effect of the composite material prepared in example 1 of the present invention under natural light (a) and under ultraviolet 365nm (b).
FIG. 4 shows the glass top development effect of the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite material prepared in example 2 under the blue light of 450 nm.
FIG. 5 shows the glass top development effect of the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite prepared in example 2 according to the invention at 365 nm.
Fig. 6 is a developed photograph of 365nm ultraviolet glass (a), copper plate (b), ceramic tile (c), aluminum plate (d), leather (e) and paper (f) of the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite prepared in example 2 of the present invention.
Detailed Description
Example 1
A preparation method of nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder comprises the following specific operations:
dissolving 6 millimole of lactic acid in 30mL of distilled water, adding 3 millimole of triethanolamine after complete dissolution, stirring until complete dissolution, and adding 1.5 millimole of GdCl prepared in advance 3 Adding into the mixed solution, transferring the mixed solution into a 700W microwave oven for microwave heating for 20min, cooling, filtering to remove insoluble substances, dialyzing and purifying to obtain carbon-doped dots, and drying at 110 ℃ to obtain brown nitrogen gadolinium-doped carbon dots. The mass ratio of the carbon source, the nitrogen source and the gadolinium chloride used was 4.
Weighing 1 g of prepared nitrogen-gadolinium doped carbon dots, dissolving in 30mL of distilled water, adding 10 g of diatomite, reacting in a hydrothermal kettle at 250 ℃ for 2h, washing, filtering, and drying the obtained solid at 110 ℃ for 4h to obtain yellow nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder. The particle size of the nano composite material is 2-20 microns, the ground nitrogen-gadolinium doped carbon dot-diatomite nano composite material powder is lightly dipped by a fingerprint brush by utilizing a classical powder display method, fingerprints are displayed along the flow direction of fingerprint lines until the lines of potential fingerprint samples are clearly displayed, and the potential fingerprint samples are irradiated and excited by ultraviolet 365nm or blue light 450nm to show green fluorescence. The mastoid thread and its detailed features are fixed with a digital camera or microscope.
The transmission electron microscope image of the carbon dots prepared in example 1 is shown in fig. 1, the fluorescence spectrum of the prepared nitrogen gadolinium doped carbon dot-diatomite nanocomposite is shown in fig. 2, and the powder comparison effect of the prepared composite under natural light (a) and ultraviolet 365nm (b) is shown in fig. 3.
Examples 2-3 the material ratios and the operating procedure were the same as in example 1, except that the carbon source used was different.
Example 2
A preparation method of nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder comprises the following specific operations:
6 mmol of mandelic acid was dissolved in 30mL of distilled water, and after complete dissolution, 3 mmol of triethanolamine was added and stirred until complete dissolution, and 1.5 mmol of GdCl prepared in advance was added 3 Adding the mixture into the mixed solution, transferring the mixed solution into a 700W microwave oven for microwave heating for 20min, cooling, filtering to remove insoluble substances, dialyzing and purifying to obtain carbon-doped dots, and drying at 110 ℃ to obtain the brown nitrogen gadolinium-doped carbon dots. The mass ratio of the carbon source, the nitrogen source and the gadolinium chloride used was 4.
Weighing 1 g of prepared nitrogen-gadolinium doped carbon dots, dissolving in 30mL of distilled water, adding 10 g of diatomite, reacting in a hydrothermal kettle at 200 ℃ for 2h, washing, filtering, and drying the obtained solid at 110 ℃ for 4h to obtain yellow nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder. The particle size of the nano composite material is 2-20 microns, the ground nitrogen-gadolinium doped carbon dot-diatomite nano composite material powder is lightly dipped by a fingerprint brush by utilizing a classical powder display method, fingerprints are displayed along the flow direction of fingerprint lines until the lines of potential fingerprint samples are clearly displayed, and the potential fingerprint samples are irradiated and excited by ultraviolet 365nm or blue light 450nm to show green fluorescence. The mastoid thread and its detailed features can be fixed by a digital camera or a microscope.
The development effect of the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite prepared in example 2 on glass under blue light of 450nm is shown in fig. 4, the development effect of the composite on glass under ultraviolet 365nm is shown in fig. 5, and the development photos of the composite on glass (a), copper plate (b), ceramic tile (c), aluminum plate (d), leather (e) and paper (f) under ultraviolet 365nm are shown in fig. 6.
Example 3
A preparation method of nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder comprises the following specific operations:
dissolving 6 mmol malic acid in 30mL distilled water, dissolving completely, adding 3 mmol triethanolamine, stirring to dissolve completely, and mixing with 1.5 mmol GdCl 3 Adding into the mixed solution, transferring the mixed solution into a 700W microwave oven for microwave heating for 20min, cooling, filtering to remove insoluble substances, dialyzing and purifying to obtain carbon-doped dots, and drying at 110 ℃ to obtain brown nitrogen gadolinium-doped carbon dots. The mass ratio of the carbon source, the nitrogen source and the gadolinium chloride used was 4.
Weighing 1 g of the prepared nitrogen gadolinium doped carbon dots, dissolving the nitrogen gadolinium doped carbon dots in 30mL of distilled water, adding 10 g of diatomite, reacting in a hydrothermal kettle at 180 ℃ for 2h, washing, filtering, and drying the obtained solid at 110 ℃ for 4h to obtain yellow nitrogen gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder. The particle size of the nano composite material is 2-20 microns, the ground nitrogen-gadolinium doped carbon dot-diatomite nano composite material powder is lightly dipped by a fingerprint brush by utilizing a classical powder display method, fingerprints are displayed along the flow direction of fingerprint lines until the lines of potential fingerprint samples are clearly displayed, and the potential fingerprint samples are irradiated and excited by ultraviolet 365nm or blue light 450nm to show green fluorescence. The mastoid thread and its detailed features can be fixed by a digital camera or a microscope.
Example 4 the material ratio and the operation procedure are the same as example 1, except that the nitrogen source used in example 4 is diethanolamine.
Example 4
A preparation method of nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder comprises the following specific operations:
6 millimole of lactic acid was dissolved in 30mL of distilled water, and after completely dissolving, 3 millimole of diethanolamine was added and stirred until completely dissolving, and 1.5 millimole of GdCl prepared in advance was added 3 Adding into the mixed solution, transferring the mixed solution into a 700W microwave oven for microwave heating for 20min, cooling, filtering to remove insoluble substances, dialyzing and purifying to obtain carbon-doped dots, and drying at 110 ℃ to obtain brown nitrogen gadolinium-doped carbon dots. The mass ratio of the carbon source, the nitrogen source and the gadolinium chloride used was 4.
Weighing 1 g of prepared nitrogen-gadolinium doped carbon dots, dissolving in 30mL of distilled water, adding 10 g of diatomite, reacting in a hydrothermal kettle at 250 ℃ for 2h, washing, filtering, and drying the obtained solid at 110 ℃ for 4h to obtain yellow nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder. The particle size of the composite material is 2-20 microns, the ground nitrogen-gadolinium doped carbon dot-diatomite nano composite material powder is lightly dipped by a fingerprint brush by utilizing a classical powder visualization method, fingerprints are brushed to visualize along the flow direction of fingerprint lines until the lines of potential fingerprint samples are clearly shown, and the potential fingerprint samples are irradiated and excited by ultraviolet 365nm or blue light 450nm to show green fluorescence. The mastoid thread and its detailed features can be fixed by a digital camera or a microscope.
Example 5 the material ratio and the operation procedure are the same as example 2, except that the nitrogen source used in example 5 is diethanolamine.
Example 5
A preparation method of nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder comprises the following specific operations:
6 mmol of mandelic acid is dissolved in 30mL of distilled water, and after complete dissolution, 3 mmol of diethanolamine is added and stirred until complete dissolution, and then 1.5 mmol of GdCl prepared in advance is added 3 Adding into the above mixed solution, transferring the mixed solution into 700W microwave oven, heating for 20min, cooling, filtering to remove insoluble substances, dialyzing, and purifyingAnd obtaining the carbon-doped dots, and drying at 110 ℃ to obtain the brown carbon-doped gadolinium nitrogen dots. The mass ratios of the carbon source, nitrogen source and gadolinium chloride required were 4.
Weighing 1 g of prepared nitrogen-gadolinium doped carbon dots, dissolving in 30mL of distilled water, adding 10 g of diatomite, reacting in a hydrothermal kettle at 200 ℃ for 2h, washing, filtering, and drying the obtained solid at 110 ℃ for 4h to obtain yellow nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder. The particle size of the composite material is 2-20 microns, the ground nitrogen-gadolinium doped carbon dot-diatomite nano composite material powder is lightly dipped by a fingerprint brush by utilizing a classical powder visualization method, fingerprints are brushed to visualize along the flow direction of fingerprint lines until the lines of potential fingerprint samples are clearly shown, and the potential fingerprint samples are irradiated and excited by ultraviolet 365nm or blue light 450nm to show green fluorescence. The mastoid thread and its detailed features may be fixed by a digital camera or a microscope.
Example 6 the material ratio and the operation procedure are the same as example 3, except that the nitrogen source used in example 6 is diethanolamine.
Example 6
A preparation method of nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder comprises the following specific operations:
dissolving 6 mmol malic acid in 30mL distilled water, adding 3 mmol diethanolamine and stirring to dissolve completely, and mixing with 1.5 mmol GdCl 3 Adding into the mixed solution, transferring the mixed solution into a 700W microwave oven for microwave heating for 20min, cooling, filtering to remove insoluble substances, dialyzing and purifying to obtain carbon-doped dots, and drying at 110 ℃ to obtain brown nitrogen gadolinium-doped carbon dots. The required mass ratios of carbon source, nitrogen source and gadolinium chloride were 4.
Weighing 1 g of prepared nitrogen-gadolinium doped carbon dots, dissolving in 30mL of distilled water, adding 10 g of diatomite, reacting in a hydrothermal kettle at 180 ℃ for 2h, washing, filtering, and drying the obtained solid at 110 ℃ for 4h to obtain yellow nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder. The particle size of the composite material is 2-20 microns, the ground nitrogen-gadolinium doped carbon dot-diatomite nano composite material powder is lightly dipped by a fingerprint brush by utilizing a classical powder visualization method, fingerprints are brushed to visualize along the flow direction of fingerprint lines until the lines of potential fingerprint samples are clearly shown, and the potential fingerprint samples are irradiated and excited by ultraviolet 365nm or blue light 450nm to show green fluorescence. The mastoid thread and its detailed features may be fixed by a digital camera or a microscope.
Example 7 the material ratio and the operation procedure were the same as those of example 1 and example 4, except that monoethanolamine was used as the nitrogen source in example 7.
Example 7
A preparation method of nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder comprises the following specific operations:
6 mmol of lactic acid was dissolved in 30mL of distilled water and, after complete dissolution, 3 mmol of monoethanolamine was added and stirred until complete dissolution, and 1.5 mmol of GdCl prepared in advance was added 3 Adding into the mixed solution, transferring the mixed solution into a 700W microwave oven for microwave heating for 20min, cooling, filtering to remove insoluble substances, dialyzing and purifying to obtain carbon-doped dots, and drying at 110 ℃ to obtain brown nitrogen gadolinium-doped carbon dots. The mass ratio of the carbon source, the nitrogen source and the gadolinium chloride used was 4.
Weighing 1 g of prepared nitrogen-gadolinium doped carbon dots, dissolving in 30mL of distilled water, adding 10 g of diatomite, reacting in a hydrothermal kettle at 250 ℃ for 2h, washing, filtering, and drying the obtained solid at 110 ℃ for 4h to obtain yellow nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder. The particle size of the composite material is 2-20 microns, the ground nitrogen-gadolinium doped carbon dot-diatomite nano composite material powder is lightly dipped by a fingerprint brush by utilizing a classical powder visualization method, fingerprints are brushed to visualize along the flow direction of fingerprint lines until the lines of potential fingerprint samples are clearly shown, and the potential fingerprint samples are irradiated and excited by ultraviolet 365nm or blue light 450nm to show green fluorescence. The mastoid thread and its detailed features can be fixed by a digital camera or a microscope.
Example 8 the material ratio and the operation procedure are the same as those of example 2 and example 5, except that monoethanolamine is used as the nitrogen source in example 8.
Example 8
A preparation method of nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder comprises the following specific operations:
6 mmol of mandelic acid was dissolved in 30mL of distilled water, and after complete dissolution, 3 mmol of monoethanolamine was added and stirred until complete dissolution, and 1.5 mmol of GdCl prepared in advance was added 3 Adding into the mixed solution, transferring the mixed solution into a 700W microwave oven for microwave heating for 20min, cooling, filtering to remove insoluble substances, dialyzing and purifying to obtain carbon-doped dots, and drying at 110 ℃ to obtain brown nitrogen gadolinium-doped carbon dots. The required mass ratios of carbon source, nitrogen source and gadolinium chloride were 4.
Weighing 1 g of prepared nitrogen-gadolinium doped carbon dots, dissolving in 30mL of distilled water, adding 10 g of diatomite, reacting in a hydrothermal kettle at 200 ℃ for 2h, washing, filtering, and drying the obtained solid at 110 ℃ for 4h to obtain yellow nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder. The particle size of the composite material is 2-20 micrometers, the ground nitrogen-gadolinium doped carbon dot-diatomite nano composite material powder is lightly dipped by a fingerprint brush by utilizing a classical powder visualization method, fingerprints are brushed and visualized along the flowing direction of fingerprint lines until the lines of potential fingerprint samples are clearly shown, and the fingerprint lines are irradiated and excited by ultraviolet 365nm or blue light 450nm to show green fluorescence. The mastoid thread and its detailed features may be fixed by a digital camera or a microscope.
Example 9 the material ratio and the operation procedure were the same as those of examples 3 and 6, except that monoethanolamine was used as the nitrogen source in example 9.
Example 9
A preparation method of nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder comprises the following specific operations:
dissolving 6 mmol malic acid in 30mL distilled water, adding 3 mmol monoethanolamine, stirring to dissolve completely, and mixing with 1.5 mmol GdCl 3 Adding into the above mixed solution, transferring the mixed solution into 700W microwave oven, microwave heating for 20min, cooling, filtering to remove insoluble substances, dialyzing and purifying to obtain carbon-doped dots, and oven drying at 110 deg.C to obtain brownThe nitrogen gadolinium doped carbon dots. The mass ratio of the carbon source, the nitrogen source and the gadolinium chloride used was 4.
Weighing 1 g of prepared nitrogen-gadolinium doped carbon dots, dissolving in 30mL of distilled water, adding 10 g of diatomite, reacting in a hydrothermal kettle at 180 ℃ for 2h, washing, filtering, and drying the obtained solid at 110 ℃ for 4h to obtain yellow nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder. The particle size of the composite material is 2-20 microns, the ground nitrogen-gadolinium doped carbon dot-diatomite nano composite material powder is lightly dipped by a fingerprint brush by utilizing a classical powder visualization method, fingerprints are brushed to visualize along the flow direction of fingerprint lines until the lines of potential fingerprint samples are clearly shown, and the potential fingerprint samples are irradiated and excited by ultraviolet 365nm or blue light 450nm to show green fluorescence. The mastoid thread and its detailed features can be fixed by a digital camera or a microscope.
Example 10 material ratio and operation procedure are the same as example 1, except that the amounts of the carbon source, nitrogen source and gadolinium chloride used in example 10 are 8.
Example 10
A preparation method of nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder comprises the following specific operations:
dissolving 6 mmol of lactic acid in 30mL of distilled water, adding 3 mmol of triethanolamine, stirring to dissolve completely, and adding 0.75 mmol of GdCl 3 Adding into the mixed solution, transferring the mixed solution into a 700W microwave oven for microwave heating for 20min, cooling, filtering to remove insoluble substances, dialyzing and purifying to obtain carbon-doped dots, and drying at 110 ℃ to obtain brown nitrogen gadolinium-doped carbon dots. The mass ratio of the carbon source, the nitrogen source and the gadolinium chloride used was 8.
Weighing 1 g of prepared nitrogen-gadolinium doped carbon dots, dissolving in 30mL of distilled water, adding 10 g of diatomite, reacting in a hydrothermal kettle at 250 ℃ for 2h, washing, filtering, and drying the obtained solid at 110 ℃ for 4h to obtain yellow nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder. The particle size of the composite material is 2-20 microns, the ground nitrogen-gadolinium doped carbon dot-diatomite nano composite material powder is lightly dipped by a fingerprint brush by utilizing a classical powder visualization method, fingerprints are brushed to visualize along the flow direction of fingerprint lines until the lines of potential fingerprint samples are clearly shown, and the potential fingerprint samples are irradiated and excited by ultraviolet 365nm or blue light 450nm to show green fluorescence. The mastoid thread and its detailed features can be fixed by a digital camera or a microscope.
Example 11 material ratio and operation procedure are the same as example 2, except that the amounts of the carbon source, nitrogen source and gadolinium chloride used in example 11 are 8.
Example 11
A preparation method of nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder comprises the following specific operations:
6 mmol of mandelic acid is dissolved in 30mL of distilled water, and after complete dissolution, 3 mmol of triethanolamine is added and stirred until complete dissolution, and 0.75 mmol of GdCl prepared in advance is added 3 Adding into the mixed solution, transferring the mixed solution into a 700W microwave oven for microwave heating for 20min, cooling, filtering to remove insoluble substances, dialyzing and purifying to obtain carbon-doped dots, and drying at 110 ℃ to obtain brown nitrogen gadolinium-doped carbon dots. The mass ratio of the carbon source, the nitrogen source and the gadolinium chloride used was 8.
Weighing 1 g of prepared nitrogen-gadolinium doped carbon dots, dissolving in 30mL of distilled water, adding 10 g of diatomite, reacting in a hydrothermal kettle at 200 ℃ for 2h, washing, filtering, and drying the obtained solid at 110 ℃ for 4h to obtain yellow nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder. The particle size of the composite material is 2-20 microns, the ground nitrogen-gadolinium doped carbon dot-diatomite nano composite material powder is lightly dipped by a fingerprint brush by utilizing a classical powder visualization method, fingerprints are brushed to visualize along the flow direction of fingerprint lines until the lines of potential fingerprint samples are clearly shown, and the potential fingerprint samples are irradiated and excited by ultraviolet 365nm or blue light 450nm to show green fluorescence. The mastoid thread and its detailed features can be fixed by a digital camera or a microscope.
Example 12 material ratio and operation procedure are the same as example 3, except that the amounts of the carbon source, nitrogen source and gadolinium chloride used in example 12 are 8.
Example 12
A preparation method of nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder comprises the following specific operations:
dissolving 6 mmol malic acid in 30mL distilled water, dissolving completely, adding 3 mmol triethanolamine, stirring to dissolve completely, and adding 0.75 mmol GdCl 3 Adding into the mixed solution, transferring the mixed solution into a 700W microwave oven for microwave heating for 20min, cooling, filtering to remove insoluble substances, dialyzing and purifying to obtain carbon-doped dots, and drying at 110 ℃ to obtain brown nitrogen gadolinium-doped carbon dots. The mass ratio of the carbon source, the nitrogen source and the gadolinium chloride used was 8.
Weighing 1 g of the prepared nitrogen gadolinium doped carbon dots, dissolving the nitrogen gadolinium doped carbon dots in 30mL of distilled water, adding 10 g of diatomite, reacting in a hydrothermal kettle at 180 ℃ for 2h, washing, filtering, and drying the obtained solid at 110 ℃ for 4h to obtain yellow nitrogen gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder. The particle size of the composite material is 2-20 microns, the ground nitrogen-gadolinium doped carbon dot-diatomite nano composite material powder is lightly dipped by a fingerprint brush by utilizing a classical powder visualization method, fingerprints are brushed to visualize along the flow direction of fingerprint lines until the lines of potential fingerprint samples are clearly shown, and the potential fingerprint samples are irradiated and excited by ultraviolet 365nm or blue light 450nm to show green fluorescence. The mastoid thread and its detailed features can be fixed by a digital camera or a microscope.
Example 13 material ratio and operation procedure are the same as example 1 and example 10, except that the amounts of the carbon source, nitrogen source and gadolinium chloride used in example 13 are 6.
Example 13
A preparation method of nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder comprises the following specific operations:
dissolving 6 mmol of lactic acid in 30mL of distilled water, adding 2 mmol of triethanolamine, stirring to dissolve completely, and mixing with 1 mmol of GdCl 3 Adding into the above mixed solution, transferring the mixed solution into 700W microwave oven, microwave heating for 20min, cooling, filtering to remove insoluble substances, dialyzing, and purifying to obtain carbon-doped productAnd drying at 110 ℃ to obtain brown nitrogen gadolinium doped carbon dots. The mass ratio of the carbon source, the nitrogen source and the gadolinium chloride used was 6.
Weighing 1 g of prepared nitrogen-gadolinium doped carbon dots, dissolving in 30mL of distilled water, adding 10 g of diatomite, reacting in a hydrothermal kettle at 250 ℃ for 2h, washing, filtering, and drying the obtained solid at 110 ℃ for 4h to obtain yellow nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder. The particle size of the composite material is 2-20 microns, the ground nitrogen-gadolinium doped carbon dot-diatomite nano composite material powder is lightly dipped by a fingerprint brush by utilizing a classical powder visualization method, fingerprints are brushed to visualize along the flow direction of fingerprint lines until the lines of potential fingerprint samples are clearly shown, and the potential fingerprint samples are irradiated and excited by ultraviolet 365nm or blue light 450nm to show green fluorescence. The mastoid thread and its detailed features can be fixed by a digital camera or a microscope.
Example 14 material ratio and operation procedure are the same as example 2 and example 11, except that the amount of carbon source, nitrogen source and gadolinium chloride used in example 14 is 6.
Example 14
A preparation method of nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder comprises the following specific operations:
6 millimole of mandelic acid is dissolved in 30mL of distilled water, and after complete dissolution, 2 millimole of triethanolamine is added and stirred until complete dissolution, and then 1 millimole of GdCl prepared in advance is added 3 Adding the mixture into the mixed solution, transferring the mixed solution into a 700W microwave oven for microwave heating for 20min, cooling, filtering to remove insoluble substances, dialyzing and purifying to obtain carbon-doped dots, and drying at 110 ℃ to obtain the brown nitrogen gadolinium-doped carbon dots. The mass ratio of the carbon source, the nitrogen source and the gadolinium chloride used was 6.
Weighing 1 g of the prepared nitrogen gadolinium doped carbon dots, dissolving the nitrogen gadolinium doped carbon dots in 30mL of distilled water, adding 10 g of diatomite, reacting in a hydrothermal kettle at 200 ℃ for 2h, washing, filtering, and drying the obtained solid at 110 ℃ for 4h to obtain yellow nitrogen gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder. The particle size of the composite material is 2-20 microns, the ground nitrogen-gadolinium doped carbon dot-diatomite nano composite material powder is lightly dipped by a fingerprint brush by utilizing a classical powder visualization method, fingerprints are brushed to visualize along the flow direction of fingerprint lines until the lines of potential fingerprint samples are clearly shown, and the potential fingerprint samples are irradiated and excited by ultraviolet 365nm or blue light 450nm to show green fluorescence. The mastoid thread and its detailed features can be fixed by a digital camera or a microscope.
Example 15 material ratio and operation procedure are the same as example 3 and example 12, except that the amounts of the carbon source, nitrogen source and gadolinium chloride used in example 15 are 6.
Example 15
A preparation method of nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder comprises the following specific operations:
dissolving 6 mmol malic acid in 30mL distilled water, dissolving completely, adding 2 mmol triethanolamine, stirring to dissolve completely, and mixing with 1 mmol GdCl 3 Adding into the mixed solution, transferring the mixed solution into a 700W microwave oven for microwave heating for 20min, cooling, filtering to remove insoluble substances, dialyzing and purifying to obtain carbon-doped dots, and drying at 110 ℃ to obtain brown nitrogen gadolinium-doped carbon dots. The mass ratio of the carbon source, the nitrogen source and the gadolinium chloride used was 6.
Weighing 1 g of prepared nitrogen-gadolinium doped carbon dots, dissolving in 30mL of distilled water, adding 10 g of diatomite, reacting in a hydrothermal kettle at 180 ℃ for 2h, washing, filtering, and drying the obtained solid at 110 ℃ for 4h to obtain yellow nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder. The particle size of the composite material is 2-20 microns, the ground nitrogen-gadolinium doped carbon dot-diatomite nano composite material powder is lightly dipped by a fingerprint brush by utilizing a classical powder visualization method, fingerprints are brushed to visualize along the flow direction of fingerprint lines until the lines of potential fingerprint samples are clearly shown, and the potential fingerprint samples are irradiated and excited by ultraviolet 365nm or blue light 450nm to show green fluorescence. The mastoid thread and its detailed features can be fixed by a digital camera or a microscope.
Example 16 the material ratio and the operation steps are the same as those of example 1, example 10 and example 13, except that the amounts of the carbon source, the nitrogen source and the gadolinium chloride used in example 16 are 8.
Example 16
A preparation method of nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder comprises the following specific operations:
6 mmol of lactic acid was dissolved in 30mL of distilled water and completely dissolved, 1.5 mmol of triethanolamine was added thereto and stirred until completely dissolved, and 0.75 mmol of GdCl prepared in advance was added 3 Adding into the mixed solution, transferring the mixed solution into a 700W microwave oven for microwave heating for 20min, cooling, filtering to remove insoluble substances, dialyzing and purifying to obtain carbon-doped dots, and drying at 110 ℃ to obtain brown nitrogen gadolinium-doped carbon dots. The required mass ratios of carbon source, nitrogen source and gadolinium chloride were 8.
Weighing 1 g of the prepared nitrogen gadolinium doped carbon dots, dissolving the nitrogen gadolinium doped carbon dots in 30mL of distilled water, adding 10 g of diatomite, reacting in a hydrothermal kettle at 250 ℃ for 2h, washing, filtering, and drying the obtained solid at 110 ℃ for 4h to obtain yellow nitrogen gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder. The particle size of the composite material is 2-20 microns, the ground nitrogen-gadolinium doped carbon dot-diatomite nano composite material powder is lightly dipped by a fingerprint brush by utilizing a classical powder visualization method, fingerprints are brushed to visualize along the flow direction of fingerprint lines until the lines of potential fingerprint samples are clearly shown, and the potential fingerprint samples are irradiated and excited by ultraviolet 365nm or blue light 450nm to show green fluorescence. The mastoid thread and its detailed features can be fixed by a digital camera or a microscope.
Example 17 material ratio and operation procedure are the same as example 2, example 11 and example 14, except that the amount of carbon source, nitrogen source and gadolinium chloride used in example 17 is 8.
Example 17
A preparation method of nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder comprises the following specific operations:
6 mmol of mandelic acid is dissolved in 30mL of distilled water, and after complete dissolution, 1.5 mmol of triethanolamine is added and stirred until complete dissolution, and 0.75 mmol of GdCl prepared in advance is added 3 Adding into the above mixed solution, and mixingAnd transferring the solution to a 700W microwave oven for microwave heating for 20min, cooling, filtering to remove insoluble substances, dialyzing and purifying to obtain carbon-doped dots, and drying at 110 ℃ to obtain the brown nitrogen-gadolinium doped carbon dots. The mass ratio of the carbon source, the nitrogen source and the gadolinium chloride used was 8.
Weighing 1 g of the prepared nitrogen gadolinium doped carbon dots, dissolving the nitrogen gadolinium doped carbon dots in 30mL of distilled water, adding 10 g of diatomite, reacting in a hydrothermal kettle at 200 ℃ for 2h, washing, filtering, and drying the obtained solid at 110 ℃ for 4h to obtain yellow nitrogen gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder. The particle size of the composite material is 2-20 microns, the ground nitrogen-gadolinium doped carbon dot-diatomite nano composite material powder is lightly dipped by a fingerprint brush by utilizing a classical powder visualization method, fingerprints are brushed to visualize along the flow direction of fingerprint lines until the lines of potential fingerprint samples are clearly shown, and the potential fingerprint samples are irradiated and excited by ultraviolet 365nm or blue light 450nm to show green fluorescence. The mastoid thread and its detailed features can be fixed by a digital camera or a microscope.
Example 18 material ratio and operation procedure are the same as example 3, example 12 and example 15, except that the amount of carbon source, nitrogen source and gadolinium chloride used in example 18 is 8.
Example 18
A preparation method of nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder comprises the following specific operations:
dissolving 6 mmol malic acid in 30mL distilled water, dissolving completely, adding 1.5 mmol triethanolamine, stirring to dissolve completely, and adding 0.75 mmol GdCl 3 Adding into the mixed solution, transferring the mixed solution into a 700W microwave oven for microwave heating for 20min, cooling, filtering to remove insoluble substances, dialyzing and purifying to obtain carbon-doped dots, and drying at 110 ℃ to obtain brown nitrogen gadolinium-doped carbon dots. The mass ratio of the carbon source, the nitrogen source and the gadolinium chloride used was 8.
Weighing 1 g of prepared nitrogen-gadolinium doped carbon dots, dissolving in 30mL of distilled water, adding 10 g of diatomite, reacting in a hydrothermal kettle at 180 ℃ for 2h, washing, filtering, and drying the obtained solid at 110 ℃ for 4h to obtain yellow nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder. The particle size of the composite material is 2-20 microns, the ground nitrogen-gadolinium doped carbon dot-diatomite nano composite material powder is lightly dipped by a fingerprint brush by utilizing a classical powder visualization method, fingerprints are brushed to visualize along the flow direction of fingerprint lines until the lines of potential fingerprint samples are clearly shown, and the potential fingerprint samples are irradiated and excited by ultraviolet 365nm or blue light 450nm to show green fluorescence. The mastoid thread and its detailed features can be fixed by a digital camera or a microscope.
As shown in table 1, the preparation method of the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite is the same as that of example 1, except that different carbon sources and nitrogen sources and carbon source/nitrogen source/gadolinium chloride ratios are adopted, and the prepared carbon dot loading amounts are slightly different.
TABLE 1 materials, ratios and carbon point loadings for examples 1-18
Under different materials and proportions, the carbon dots of the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite are different in adhesion but basically kept between 4% and 5%, and can be uniformly dispersed on the surface of a base material, and as can be seen from Table 1, a carbon source, a nitrogen source and GdCl 3 The different proportions of the carbon particles determine the different carbon loading amounts, directly influence the adhesion condition of carbon points on the surface of the substrate and influence the final display effect of the latent fingerprints.
According to the embodiment of the invention, the fluorescent nitrogen gadolinium doped carbon dot-diatomite nano composite material is synthesized through simple microwaves, so that the problem of the size effect of the carbon dots is solved, the composite material is endowed with good developing performance, and the adaptability of the composite material to different substrate surfaces is improved. The technical scheme provided by the embodiment of the invention can provide a brand new idea for developing the latent fingerprint.
Claims (9)
1. The preparation method of the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder is characterized by comprising the following steps of:
weighing carbon source and nitrogen source according to a certain proportion, adding distilled water, stirring uniformly and completely dissolving, and then weighing GdCl according to a certain proportion 3 Adding the mixture into the solution, transferring the mixed solution into a microwave oven for microwave heating, naturally cooling to room temperature, filtering to remove insoluble substances, dialyzing and purifying to obtain carbon-doped dots, and drying to obtain brown carbon-doped gadolinium nitride dots;
dissolving the prepared nitrogen-gadolinium doped carbon dots in distilled water, adding matrix diatomite, uniformly mixing, reacting in a hydrothermal reaction kettle, washing, filtering, and drying the obtained solid to obtain the yellow nitrogen-gadolinium doped carbon dot-diatomite nanocomposite.
2. The method for preparing nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder according to claim 1, wherein the carbon source is selected from glycolic acid, lactic acid, malic acid and mandelic acid, and the nitrogen source is selected from monoethanolamine, diethanolamine and triethanolamine.
3. The preparation method of the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder as claimed in claim 1, wherein the mass ratio of the carbon source, the nitrogen source and the gadolinium chloride is (1-10), (1-5) and (1-2).
4. The preparation method of the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder according to claim 1, wherein the prepared nitrogen-gadolinium doped carbon dot and the matrix diatomite are mixed according to a mass ratio of 1.
5. The preparation method of the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder as claimed in claim 1, wherein the nitrogen source comprises a carbon source, a nitrogen source and GdCl 3 In the mixing ofThe solution is heated in a microwave oven of 700W for 5-60 min.
6. The preparation method of the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder as claimed in claim 1, wherein the prepared nitrogen-gadolinium doped carbon dot is dissolved in distilled water, and after the matrix diatomite is added, the mixture is reacted in a hydrothermal reaction kettle at 180-250 ℃ for 1-2h.
7. The preparation method of the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder according to claim 1, wherein the loading amount of the prepared carbon dots is 4% -5%, the particle size of the prepared composite material is 2-20 microns, and green fluorescence can be seen under 365nm or 450nm light irradiation.
8. The nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder is characterized by being prepared according to any one of claims 1 to 7.
9. The application of the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder disclosed by claim 8 in the aspect of latent fingerprint imaging specifically comprises the following steps:
step 1: preparation of latent oil-sweat mixed fingerprints
Pressing the fingerprint on the surface of the carrier, and transferring the oily sweat mixture on the finger to the surface of the carrier to form a fingerprint latent print so as to obtain an oily sweat latent fingerprint sample; the latent fingerprint carrier is glass, metal, paper, plastic, food packaging materials, leather and ceramic;
step 2: powder display method for displaying finger print
Dipping the prepared nano composite material developing powder by using a fingerprint brush, brushing the nano composite material developing powder on the latent fingerprints left on the surface of the carrier, shaking off redundant appearing powder after the lines of the fingerprints are found, and continuously brushing the redundant powder by using the fingerprint brush along the flow direction of the fingerprint lines until the lines of the fingerprint sample are clearly shown;
and step 3: extracting fingerprints
And a 365nm or 450nm light source is selected to obliquely irradiate on the fingerprint lines after the latent fingerprint is displayed, and a digital camera or a microscope is used for photographing and imaging, so that the visible fingerprint is green and luminous, and the aim of displaying the latent fingerprint by fluorescence is fulfilled.
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| CN115074120A (en) * | 2022-06-13 | 2022-09-20 | 中国刑事警察学院 | Carbon dot/diatomite fluorescent composite powder and preparation method and application thereof |
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| CN104288789A (en) * | 2014-09-09 | 2015-01-21 | 上海纳米技术及应用国家工程研究中心有限公司 | Gadolinium-doped difunctional carbon nanoparticles and preparation method and application thereof |
| CN115074120A (en) * | 2022-06-13 | 2022-09-20 | 中国刑事警察学院 | Carbon dot/diatomite fluorescent composite powder and preparation method and application thereof |
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