CN115746836B - 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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Classifications
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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, then modifying the carbon dots on the surface of a core made of diatomite to prepare a yellow nitrogen-gadolinium doped carbon dot-diatomite nanocomposite, and absorbing and combining the prepared nitrogen-gadolinium doped carbon dots through a diatomite multi-stage pore structure to eliminate fluorescence quenching phenomenon caused by carbon dot aggregation and obviously enhance fluorescence intensity; a365 nm or 450nm light source is obliquely irradiated on the fingerprint lines after the appearance, and a digital camera or a microscope is used for photographing and imaging, so that the fingerprint is visible to emit green light. After being irradiated by the light source, the imaging of the latent fingerprints on various substrate materials can be realized quickly, simply and 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
Fingerprint has the characteristics of different people, invariable life, trace of touching objects and the like, and has the reputation of 'the king of evidence'. One of the important bases for validating crimes and identifying criminal suspects in judicial practice activities is the most effective weapon and means for striking criminals. The finger prints are basically invisible in the field investigation and are potential traces, and the traditional development methods comprise a powder development method, a 502 development method, an iodine fumigation method, an ninhydrin method, a silver nitrate method and the like, and the traditional development powder has the characteristics of fine particles and easy floatation and is easy to cause serious harm to the body health of professional technicians. The research of developing powder which is cheap and easy to obtain, nontoxic and pollution-free is always a research hotspot of professional technicians.
Rare earth oxide (Y) 2 O 3 、Gd 2 O 3 And CeO 2 ) The potential applications in multiple fields are of great interest due to their unique optical properties and good stability. Wherein the criminal technician exploits its stable fluorescent properties as one of the fingerprint revealing powders. However, rare earth of the multifunctional material is not suitable for large-scale fingerprint appearance as strategic resources.
The nanomaterial, also referred to as ultrafine particulate material, refers to particles having a size between 1 and 100 nm. The product has unique physical and chemical properties due to its unique size effect. In order to eliminate the influence of background color in the developing process, the nano fluorescent powder effectively solves the problem, but the problems of cost and particle suspension are not solved all the time.
Carbon dots refer to carbon particles with fluorescent properties having a size of less than 20 nm. The polymer-based aggregated particles may have a single-layer or multi-layer graphite structure. The fluorescent light has the unique optical properties of high fluorescence intensity, adjustable emission wavelength, wider excitation wavelength range and the like, and simultaneously, the preparation cost of carbon dots is lower, the carbon dots are easy to obtain in life, and common carbon-containing organic matters such as cereal grass, straw and the like can be obtained. The method has little harm to the environment and no toxic effect, and the research of the method represents that the research of luminescent nano particles enters a new stage.
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, composition and proportion of raw materials, and the like, and the excellent fluorescence performance of the carbon dots is utilized to replace the traditional fluorescent powder, so that the carbon dots have huge tension when being used for developing potential fingerprints in criminal science and technology. However, further applications in fingerprint development are limited by the phenomenon of aggregation-induced fluorescence quenching of nanocarbon sites.
Therefore, in order to overcome the defects of carbon dots, development of a surface carbon dot composite material with stable surface morphology, uniform particle dispersion and excellent luminous performance is needed, so that the surface carbon dot composite material is used for identifying, imaging, checking and identifying sweat latent fingerprints in an actual working environment. The invention provides a preparation method of a nitrogen-gadolinium doped carbon dot-diatomite nanocomposite by using 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 aggregation of carbon dot particles, realizes solid fluorescence, improves the stability and strength of fluorescence emission by utilizing the unique optical property of Gd, and shows the practical application value of 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 in operation, high in efficiency, convenient, safe, quick 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 excellent luminescence characteristic of the 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 continuous, stable and efficient solid-state luminescence effect under the excitation of a light source, and the site fingerprint can be quickly displayed.
The preparation method of the 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 weighing GdCl according to a certain proportion 3 Adding the mixture into the solution, transferring the mixed solution into a 700W microwave oven, heating for 5-60 min by microwaves, changing the colorless solution into dark brown, naturally cooling to room temperature, filtering to remove insoluble substances, dialyzing and purifying to obtain carbon doped points, and drying at 100-110 ℃ to obtain brown nitrogen-gadolinium doped carbon points;
dissolving the prepared nitrogen-gadolinium doped carbon dots in distilled water, adding matrix diatomite according to a mass ratio of 1:10, uniformly mixing, reacting in a hydrothermal reaction kettle at 180-250 ℃ for 1-2h, washing, filtering, and drying the obtained solid at 100-110 ℃ for 3-4h to obtain the yellow nitrogen-gadolinium doped carbon dot-diatomite nanocomposite.
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): 1-5): 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 365nm or 450nm light irradiation.
The nitrogen-gadolinium doped carbon dot-diatomite nanocomposite prepared by the invention has the characteristics of green fluorescence, uniform particle size and stability of 2-20 microns, and is used for latent fingerprint 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 fingerprint
And pressing the fingerprint on the surface of the carrier, and transferring the oil sweat mixture on the finger to the surface of the carrier to form a fingerprint potential print, thereby obtaining an oil sweat potential fingerprint sample.
Step 2: powder visualization method for developing fingerprints
The fingerprint brush is used for dipping a small amount of prepared nano composite material developing powder, brushing is performed on potential fingerprints left on the surface of a carrier, after the fingerprints are found, the excessive developing powder is shaken out, and the fingerprint brush is continuously used for brushing the excessive powder along the flow direction of the fingerprints until the fingerprints of the fingerprint sample are clearly shown.
Step 3: extracting fingerprints
A 365nm or 450nm light source is selected to obliquely irradiate on the developed fingerprint lines, a digital camera or a microscope is used for photographing and imaging, and the visible fingerprint is green and emits light, so that the purpose of fluorescent development of the latent fingerprint is achieved. 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 package, leather and ceramic.
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 liquid dispersion carbon dot aqueous solutions is poor, and the application to substrates such as glass, plastics and the like is very limited. Solid state light emitting carbon dots are prone to fluorescence quenching due to carbon dot aggregation, and research has found that dispersing carbon dots with a matrix material to maintain their fluorescence properties is a research hotspot. Although researchers have attempted to disperse carbon dots in polymer gels, the process is cumbersome; there are also researchers' microwave method to synthesize solid fluorescent carbon dots, but the active group type and quantity are limited, or the luminous intensity is weak, it is not easy to combine with the fingerprint surface texture, the fluorescent resolution is not good when the fingerprint is developed, and the second and third information of the fingerprint can not be obtained. Meanwhile, blue background interference of many objects also causes low fingerprint development clarity and contrast, and further application in the criminal science and technology field is limited. The carbon dot composite powder with stable fluorescence characteristic, good biocompatibility and good bonding capability is synthesized for fingerprint development, and meets the public security actual combat requirement.
In order to solve the problem of solid-state light-emitting limiting conditions, a proper carbon point synthesis control route (temperature, time and method) and the proportion of a carbon source, a nitrogen source and gadolinium chloride are selected, spherical porous diatomite is selected as a matrix material, after the carbon points are synthesized by microwaves, the carbon points are dispersed in matrix material diatomite by a hydrothermal synthesis method, so that hydroxyl groups and amine groups rich in the surfaces of the carbon points are physically embedded in the surface of the matrix material diatomite, the distance between carbon point particles is increased by virtue of the porous spherical structure of the diatomite and the electrostatic effect between the carbon points, particle aggregation is avoided, the composite light of photo-generated electrons and holes is weakened, and the quantum yield is improved. And further, the physical appearance of the composite material and the absorption characteristic of an absorption peak are changed, and the fingerprint development of quick response is realized. The surface of the carbon dot is functionalized by optimizing the synthesis route, so that the synthetic material is endowed with the fingerprint development characteristics of stable luminescence, good biocompatibility and stronger 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, environment friendliness and the like;
(2) The developing method disclosed by the invention is simple to operate, high in developing efficiency and suitable for popularization.
(3) According to the invention, nitrogen-gadolinium doped carbon dots are adopted as fluorescent markers to display potential fingerprints, and are uniformly dispersed in diatomite through the action of static electricity or Van der Waals, so that aggregation of carbon dot doped nano particles is avoided, and a nano composite material with higher fluorescence quantum yield, higher absorption coefficient, higher fluorescence brightness and more stable combination is produced on the surface of the diatomite.
(4) The nitrogen-gadolinium doped carbon dot-diatomite nanocomposite 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 a base material.
(5) The method overcomes the fluorescence quenching condition caused by carbon dot agglomeration in the carbon dot solution drying process, and the synthesized carbon dots are uniformly dispersed on the surface of the matrix to form a stable composite material.
Drawings
FIG. 1 is a transmission electron microscope image of a carbon dot prepared in example 1 of the present invention.
FIG. 2 is a fluorescence spectrum of nitrogen-gadolinium doped carbon dot-diatomite nanocomposite 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 ultraviolet 365nm (b).
FIG. 4 shows the development effect on glass at blue light of 450nm of the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite prepared in example 2 of the present invention.
FIG. 5 shows the development effect on glass at 365nm of ultraviolet light of the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite prepared in example 2 of the present invention.
FIG. 6 is a photograph of the development of glass (a), copper (b), ceramic tile (c), aluminum (d), leather (e) and paper (f) of the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite prepared in example 2 of the present invention at 365 nm.
Detailed Description
Example 1
The preparation method of the 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 after complete dissolution, stirring to complete dissolution, and adding 1.5 mmol of prepared GdCl 3 Adding into the mixed solution, transferring the mixed solution into a 700W microwave oven, heating for 20min by microwave, cooling, filtering, discarding insoluble substances, dialyzing, purifying to obtain carbon doped points, and oven drying at 110deg.C to obtain brown nitrogen-gadolinium doped carbon points. The mass ratio of the carbon source, the nitrogen source and the gadolinium chloride is 4:2:1.
1 gram of the prepared nitrogen-gadolinium doped carbon dots are weighed and dissolved in 30mL of distilled water, 10 grams of diatomite is added, the mixture is reacted in a hydrothermal kettle at 250 ℃ for 2 hours, the mixture is filtered after washing, and the obtained solid is dried at 110 ℃ for 4 hours, so that the yellow nitrogen-gadolinium doped carbon dots-diatomite nanocomposite latent fingerprint developing powder is obtained. The grain size of the nano composite material is 2-20 microns, a classical powder visualization method is utilized, a fingerprint brush is used for slightly dipping the ground nitrogen-gadolinium doped carbon dot-diatomite nano composite material powder, fingerprints are brushed along the flow direction of fingerprint lines until the fingerprint lines of potential fingerprint samples are clearly presented, and ultraviolet 365nm or blue light 450nm light irradiation is used for excitation, so that green fluorescence is visible. The mastoid thread and its detailed features are fixed with a digital camera or microscope.
The transmission electron microscope image of the carbon point prepared in example 1 is shown in fig. 1, the fluorescence spectrum of the prepared nitrogen-gadolinium doped carbon point-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 operating procedures were the same as example 1, except that different carbon sources were used.
Example 2
The preparation method of the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder comprises the following specific operations:
dissolving 6 mmol of mandelic acid in 30mL of distilled water, adding 3 mmol of triethanolamine after complete dissolution, stirring to complete dissolution, and adding 1.5 mmol of prepared GdCl 3 Adding into the mixed solution, transferring the mixed solution into a 700W microwave oven, heating for 20min by microwave, cooling, filtering, discarding insoluble substances, dialyzing, purifying to obtain carbon doped points, and oven drying at 110deg.C to obtain brown nitrogen-gadolinium doped carbon points. The mass ratio of the carbon source, the nitrogen source and the gadolinium chloride is 4:2:1.
1 gram of the prepared nitrogen-gadolinium doped carbon dots are weighed and dissolved in 30mL of distilled water, 10 grams of diatomite is added, the mixture is reacted in a hydrothermal kettle at 200 ℃ for 2 hours, the mixture is filtered after washing, and the obtained solid is dried at 110 ℃ for 4 hours, so that the yellow nitrogen-gadolinium doped carbon dots-diatomite nanocomposite latent fingerprint developing powder is obtained. The grain size of the nano composite material is 2-20 microns, a classical powder visualization method is utilized, a fingerprint brush is used for slightly dipping the ground nitrogen-gadolinium doped carbon dot-diatomite nano composite material powder, fingerprints are brushed along the flow direction of fingerprint lines until the fingerprint lines of potential fingerprint samples are clearly presented, and ultraviolet 365nm or blue light 450nm light irradiation is used for excitation, so that green fluorescence is visible. The mastoid thread and its detailed features can be fixed with a digital camera or microscope.
The development effect of the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite prepared in example 2 on glass at blue light of 450nm is shown in fig. 4, the development effect of the composite on glass at ultraviolet 365nm is shown in fig. 5, and the development photographs of the composite on glass (a), copper plate (b), ceramic tile (c), aluminum plate (d), leather (e) and paper (f) at ultraviolet 365nm are shown in fig. 6.
Example 3
The preparation method of the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder comprises the following specific operations:
dissolving 6 mmol of malic acid in 30mL of distilled water, adding 3 mmol of triethanolamine after complete dissolution, stirring to complete dissolution, and adding 1.5 mmol of prepared GdCl 3 Adding into the above mixed solution, and dissolvingTransferring the solution to a 700W microwave oven, heating for 20min by microwave, cooling, filtering, discarding insoluble substances, dialyzing, purifying to obtain carbon doped point, and oven drying at 110deg.C to obtain brown nitrogen-gadolinium doped carbon point. The mass ratio of the carbon source, the nitrogen source and the gadolinium chloride is 4:2:1.
1 gram of the prepared nitrogen-gadolinium doped carbon dots are weighed and dissolved in 30mL of distilled water, 10 grams of diatomite is added, the mixture is reacted in a hydrothermal kettle at 180 ℃ for 2 hours, the mixture is filtered after washing, and the obtained solid is dried at 110 ℃ for 4 hours, so that the yellow nitrogen-gadolinium doped carbon dots-diatomite nanocomposite latent fingerprint developing powder is obtained. The grain size of the nano composite material is 2-20 microns, a classical powder visualization method is utilized, a fingerprint brush is used for slightly dipping the ground nitrogen-gadolinium doped carbon dot-diatomite nano composite material powder, fingerprints are brushed along the flow direction of fingerprint lines until the fingerprint lines of potential fingerprint samples are clearly presented, and ultraviolet 365nm or blue light 450nm light irradiation is used for excitation, so that green fluorescence is visible. The mastoid thread and its detailed features can be fixed with a digital camera or microscope.
Example 4 the material formulation and operating procedure were the same as in example 1, except that the nitrogen source used in example 4 was diethanolamine.
Example 4
The preparation method of the 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 diethanolamine after complete dissolution, stirring to complete dissolution, and adding 1.5 mmol of prepared GdCl 3 Adding into the mixed solution, transferring the mixed solution into a 700W microwave oven, heating for 20min by microwave, cooling, filtering, discarding insoluble substances, dialyzing, purifying to obtain carbon doped points, and oven drying at 110deg.C to obtain brown nitrogen-gadolinium doped carbon points. The mass ratio of the carbon source, the nitrogen source and the gadolinium chloride is 4:2:1.
1 gram of the prepared nitrogen-gadolinium doped carbon dots are weighed and dissolved in 30mL of distilled water, 10 grams of diatomite is added, the mixture is reacted in a hydrothermal kettle at 250 ℃ for 2 hours, the mixture is filtered after washing, and the obtained solid is dried at 110 ℃ for 4 hours, so that the yellow nitrogen-gadolinium doped carbon dots-diatomite nanocomposite latent fingerprint developing powder is obtained. The particle size of the composite material is 2-20 microns, a classical powder visualization method is utilized, a fingerprint brush is used for slightly dipping the ground nitrogen-gadolinium doped carbon dot-diatomite nano composite material powder, fingerprints are brushed along the flow direction of fingerprint lines until the fingerprint lines of potential fingerprint samples are clearly presented, and ultraviolet 365nm or blue light 450nm light irradiation is used for excitation, so that green fluorescence is visible. The mastoid thread and its detailed features can be fixed with a digital camera or microscope.
Example 5 the material ratios and operating procedures were the same as in example 2 except that the nitrogen source used in example 5 was diethanolamine.
Example 5
The preparation method of the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder comprises the following specific operations:
dissolving 6 mmol of mandelic acid in 30mL of distilled water, adding 3 mmol of diethanolamine after complete dissolution, stirring to complete dissolution, and adding 1.5 mmol of prepared GdCl 3 Adding into the mixed solution, transferring the mixed solution into a 700W microwave oven, heating for 20min by microwave, cooling, filtering, discarding insoluble substances, dialyzing, purifying to obtain carbon doped points, and oven drying at 110deg.C to obtain brown nitrogen-gadolinium doped carbon points. The ratio of the amounts of the substances required for the carbon source, the nitrogen source and gadolinium chloride is 4:2:1.
1 gram of the prepared nitrogen-gadolinium doped carbon dots are weighed and dissolved in 30mL of distilled water, 10 grams of diatomite is added, the mixture is reacted in a hydrothermal kettle at 200 ℃ for 2 hours, the mixture is filtered after washing, and the obtained solid is dried at 110 ℃ for 4 hours, so that the yellow nitrogen-gadolinium doped carbon dots-diatomite nanocomposite latent fingerprint developing powder is obtained. The particle size of the composite material is 2-20 microns, a classical powder visualization method is utilized, a fingerprint brush is used for slightly dipping the ground nitrogen-gadolinium doped carbon dot-diatomite nano composite material powder, fingerprints are brushed along the flow direction of fingerprint lines until the fingerprint lines of potential fingerprint samples are clearly presented, and ultraviolet 365nm or blue light 450nm light irradiation is used for excitation, so that green fluorescence is visible. The mastoid thread and its detailed features can be fixed with a digital camera or microscope.
Example 6 the material formulation and operating procedure were the same as in example 3 except that the nitrogen source used in example 6 was diethanolamine.
Example 6
The preparation method of the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder comprises the following specific operations:
dissolving 6 mmol of malic acid in 30mL of distilled water, adding 3 mmol of diethanolamine after complete dissolution, stirring to complete dissolution, and adding 1.5 mmol of prepared GdCl 3 Adding into the mixed solution, transferring the mixed solution into a 700W microwave oven, heating for 20min by microwave, cooling, filtering, discarding insoluble substances, dialyzing, purifying to obtain carbon doped points, and oven drying at 110deg.C to obtain brown nitrogen-gadolinium doped carbon points. The ratio of the amounts of the substances required for the carbon source, the nitrogen source and gadolinium chloride is 4:2:1.
1 gram of the prepared nitrogen-gadolinium doped carbon dots are weighed and dissolved in 30mL of distilled water, 10 grams of diatomite is added, the mixture is reacted in a hydrothermal kettle at 180 ℃ for 2 hours, the mixture is filtered after washing, and the obtained solid is dried at 110 ℃ for 4 hours, so that the yellow nitrogen-gadolinium doped carbon dots-diatomite nanocomposite latent fingerprint developing powder is obtained. The particle size of the composite material is 2-20 microns, a classical powder visualization method is utilized, a fingerprint brush is used for slightly dipping the ground nitrogen-gadolinium doped carbon dot-diatomite nano composite material powder, fingerprints are brushed along the flow direction of fingerprint lines until the fingerprint lines of potential fingerprint samples are clearly presented, and ultraviolet 365nm or blue light 450nm light irradiation is used for excitation, so that green fluorescence is visible. The mastoid thread and its detailed features can be fixed with a digital camera or microscope.
Example 7 the material ratios and operating steps were the same as in examples 1 and 4, except that the nitrogen source used in example 7 was monoethanolamine.
Example 7
The preparation method of the 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 monoethanolamine after complete dissolution, stirring to complete dissolution, and adding 1.5 mmol of prepared GdCl 3 Adding into the above mixed solution, transferring the mixed solution into 700W microwave oven, heating for 20min, cooling, filtering to remove insoluble substances, and dialyzingPurifying to obtain carbon doped points, and drying at 110 ℃ to obtain brown nitrogen-gadolinium doped carbon points. The mass ratio of the carbon source, the nitrogen source and the gadolinium chloride is 4:2:1.
1 gram of the prepared nitrogen-gadolinium doped carbon dots are weighed and dissolved in 30mL of distilled water, 10 grams of diatomite is added, the mixture is reacted in a hydrothermal kettle at 250 ℃ for 2 hours, the mixture is filtered after washing, and the obtained solid is dried at 110 ℃ for 4 hours, so that the yellow nitrogen-gadolinium doped carbon dots-diatomite nanocomposite latent fingerprint developing powder is obtained. The particle size of the composite material is 2-20 microns, a classical powder visualization method is utilized, a fingerprint brush is used for slightly dipping the ground nitrogen-gadolinium doped carbon dot-diatomite nano composite material powder, fingerprints are brushed along the flow direction of fingerprint lines until the fingerprint lines of potential fingerprint samples are clearly presented, and ultraviolet 365nm or blue light 450nm light irradiation is used for excitation, so that green fluorescence is visible. The mastoid thread and its detailed features can be fixed with a digital camera or microscope.
Example 8 the material ratios and operating procedures were the same as in examples 2 and 5, except that the nitrogen source used in example 8 was monoethanolamine.
Example 8
The preparation method of the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder comprises the following specific operations:
dissolving 6 mmol of mandelic acid in 30mL of distilled water, adding 3 mmol of monoethanolamine, stirring to dissolve completely, and adding 1.5 mmol of prepared GdCl 3 Adding into the mixed solution, transferring the mixed solution into a 700W microwave oven, heating for 20min by microwave, cooling, filtering, discarding insoluble substances, dialyzing, purifying to obtain carbon doped points, and oven drying at 110deg.C to obtain brown nitrogen-gadolinium doped carbon points. The ratio of the amounts of the substances required for the carbon source, the nitrogen source and gadolinium chloride is 4:2:1.
1 gram of the prepared nitrogen-gadolinium doped carbon dots are weighed and dissolved in 30mL of distilled water, 10 grams of diatomite is added, the mixture is reacted in a hydrothermal kettle at 200 ℃ for 2 hours, the mixture is filtered after washing, and the obtained solid is dried at 110 ℃ for 4 hours, so that the yellow nitrogen-gadolinium doped carbon dots-diatomite nanocomposite latent fingerprint developing powder is obtained. The particle size of the composite material is 2-20 microns, a classical powder visualization method is utilized, a fingerprint brush is used for slightly dipping the ground nitrogen-gadolinium doped carbon dot-diatomite nano composite material powder, fingerprints are brushed along the flow direction of fingerprint lines until the fingerprint lines of potential fingerprint samples are clearly presented, and ultraviolet 365nm or blue light 450nm light irradiation is used for excitation, so that green fluorescence is visible. The mastoid thread and its detailed features can be fixed with a digital camera or microscope.
Example 9 the material ratios and operating procedures were the same as in example 3 and example 6, except that the nitrogen source used in example 9 was monoethanolamine.
Example 9
The preparation method of the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder comprises the following specific operations:
dissolving 6 mmol of malic acid in 30mL of distilled water, adding 3 mmol of monoethanolamine after complete dissolution, stirring to complete dissolution, and adding 1.5 mmol of prepared GdCl 3 Adding into the mixed solution, transferring the mixed solution into a 700W microwave oven, heating for 20min by microwave, cooling, filtering, discarding insoluble substances, dialyzing, purifying to obtain carbon doped points, and oven drying at 110deg.C to obtain brown nitrogen-gadolinium doped carbon points. The mass ratio of the carbon source, the nitrogen source and the gadolinium chloride is 4:2:1.
1 gram of the prepared nitrogen-gadolinium doped carbon dots are weighed and dissolved in 30mL of distilled water, 10 grams of diatomite is added, the mixture is reacted in a hydrothermal kettle at 180 ℃ for 2 hours, the mixture is filtered after washing, and the obtained solid is dried at 110 ℃ for 4 hours, so that the yellow nitrogen-gadolinium doped carbon dots-diatomite nanocomposite latent fingerprint developing powder is obtained. The particle size of the composite material is 2-20 microns, a classical powder visualization method is utilized, a fingerprint brush is used for slightly dipping the ground nitrogen-gadolinium doped carbon dot-diatomite nano composite material powder, fingerprints are brushed along the flow direction of fingerprint lines until the fingerprint lines of potential fingerprint samples are clearly presented, and ultraviolet 365nm or blue light 450nm light irradiation is used for excitation, so that green fluorescence is visible. The mastoid thread and its detailed features can be fixed with a digital camera or microscope.
Example 10 the material ratios and operating procedures were the same as in example 1, except that the amounts of carbon source, nitrogen source and gadolinium chloride materials used in example 10 were 8:4:1.
Example 10
The preparation method of the 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 after complete dissolution, stirring to complete dissolution, and adding 0.75 mmol of prepared GdCl 3 Adding into the mixed solution, transferring the mixed solution into a 700W microwave oven, heating for 20min by microwave, cooling, filtering, discarding insoluble substances, dialyzing, purifying to obtain carbon doped points, and oven drying at 110deg.C to obtain brown nitrogen-gadolinium doped carbon points. The mass ratio of the carbon source, the nitrogen source and the gadolinium chloride is 8:4:1.
1 gram of the prepared nitrogen-gadolinium doped carbon dots are weighed and dissolved in 30mL of distilled water, 10 grams of diatomite is added, the mixture is reacted in a hydrothermal kettle at 250 ℃ for 2 hours, the mixture is filtered after washing, and the obtained solid is dried at 110 ℃ for 4 hours, so that the yellow nitrogen-gadolinium doped carbon dots-diatomite nanocomposite latent fingerprint developing powder is obtained. The particle size of the composite material is 2-20 microns, a classical powder visualization method is utilized, a fingerprint brush is used for slightly dipping the ground nitrogen-gadolinium doped carbon dot-diatomite nano composite material powder, fingerprints are brushed along the flow direction of fingerprint lines until the fingerprint lines of potential fingerprint samples are clearly presented, and ultraviolet 365nm or blue light 450nm light irradiation is used for excitation, so that green fluorescence is visible. The mastoid thread and its detailed features can be fixed with a digital camera or microscope.
Example 11 the material ratios and operating procedures were the same as in example 2 except that the amounts of carbon source, nitrogen source and gadolinium chloride materials used in example 11 were 8:4:1.
Example 11
The preparation method of the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder comprises the following specific operations:
dissolving 6 mmol of mandelic acid in 30mL of distilled water, adding 3 mmol of triethanolamine after complete dissolution, stirring to complete dissolution, and adding 0.75 mmol of prepared GdCl 3 Adding into the above mixed solution, transferring the mixed solution into 700W microwave oven, heating for 20min, cooling, filtering to remove insoluble substances, and purifying by dialysisAnd (3) obtaining carbon doped points, and drying at 110 ℃ to obtain brown nitrogen-gadolinium doped carbon points. The mass ratio of the carbon source, the nitrogen source and the gadolinium chloride is 8:4:1.
1 gram of the prepared nitrogen-gadolinium doped carbon dots are weighed and dissolved in 30mL of distilled water, 10 grams of diatomite is added, the mixture is reacted in a hydrothermal kettle at 200 ℃ for 2 hours, the mixture is filtered after washing, and the obtained solid is dried at 110 ℃ for 4 hours, so that the yellow nitrogen-gadolinium doped carbon dots-diatomite nanocomposite latent fingerprint developing powder is obtained. The particle size of the composite material is 2-20 microns, a classical powder visualization method is utilized, a fingerprint brush is used for slightly dipping the ground nitrogen-gadolinium doped carbon dot-diatomite nano composite material powder, fingerprints are brushed along the flow direction of fingerprint lines until the fingerprint lines of potential fingerprint samples are clearly presented, and ultraviolet 365nm or blue light 450nm light irradiation is used for excitation, so that green fluorescence is visible. The mastoid thread and its detailed features can be fixed with a digital camera or microscope.
Example 12 the material ratios and operating procedures were the same as in example 3 except that the amounts of carbon source, nitrogen source and gadolinium chloride materials used in example 12 were 8:4:1.
Example 12
The preparation method of the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder comprises the following specific operations:
dissolving 6 mmol of malic acid in 30mL of distilled water, adding 3 mmol of triethanolamine after complete dissolution, stirring to complete dissolution, and adding 0.75 mmol of prepared GdCl 3 Adding into the mixed solution, transferring the mixed solution into a 700W microwave oven, heating for 20min by microwave, cooling, filtering, discarding insoluble substances, dialyzing, purifying to obtain carbon doped points, and oven drying at 110deg.C to obtain brown nitrogen-gadolinium doped carbon points. The mass ratio of the carbon source, the nitrogen source and the gadolinium chloride is 8:4:1.
1 gram of the prepared nitrogen-gadolinium doped carbon dots are weighed and dissolved in 30mL of distilled water, 10 grams of diatomite is added, the mixture is reacted in a hydrothermal kettle at 180 ℃ for 2 hours, the mixture is filtered after washing, and the obtained solid is dried at 110 ℃ for 4 hours, so that the yellow nitrogen-gadolinium doped carbon dots-diatomite nanocomposite latent fingerprint developing powder is obtained. The particle size of the composite material is 2-20 microns, a classical powder visualization method is utilized, a fingerprint brush is used for slightly dipping the ground nitrogen-gadolinium doped carbon dot-diatomite nano composite material powder, fingerprints are brushed along the flow direction of fingerprint lines until the fingerprint lines of potential fingerprint samples are clearly presented, and ultraviolet 365nm or blue light 450nm light irradiation is used for excitation, so that green fluorescence is visible. The mastoid thread and its detailed features can be fixed with a digital camera or microscope.
Example 13 the material ratios and operating procedures were the same as in example 1, example 10, except that the amounts of carbon source, nitrogen source and gadolinium chloride materials used in example 13 were 6:2:1.
Example 13
The preparation method of the 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 after complete dissolution, stirring to complete dissolution, and adding 1 mmol of prepared GdCl 3 Adding into the mixed solution, transferring the mixed solution into a 700W microwave oven, heating for 20min by microwave, cooling, filtering, discarding insoluble substances, dialyzing, purifying to obtain carbon doped points, and oven drying at 110deg.C to obtain brown nitrogen-gadolinium doped carbon points. The mass ratio of the carbon source, the nitrogen source and the gadolinium chloride is 6:2:1.
1 gram of the prepared nitrogen-gadolinium doped carbon dots are weighed and dissolved in 30mL of distilled water, 10 grams of diatomite is added, the mixture is reacted in a hydrothermal kettle at 250 ℃ for 2 hours, the mixture is filtered after washing, and the obtained solid is dried at 110 ℃ for 4 hours, so that the yellow nitrogen-gadolinium doped carbon dots-diatomite nanocomposite latent fingerprint developing powder is obtained. The particle size of the composite material is 2-20 microns, a classical powder visualization method is utilized, a fingerprint brush is used for slightly dipping the ground nitrogen-gadolinium doped carbon dot-diatomite nano composite material powder, fingerprints are brushed along the flow direction of fingerprint lines until the fingerprint lines of potential fingerprint samples are clearly presented, and ultraviolet 365nm or blue light 450nm light irradiation is used for excitation, so that green fluorescence is visible. The mastoid thread and its detailed features can be fixed with a digital camera or microscope.
Example 14 the material ratios and operating procedures were the same as in example 2, example 11, except that the amounts of carbon source, nitrogen source and gadolinium chloride materials used in example 14 were 6:2:1.
Example 14
The preparation method of the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder comprises the following specific operations:
dissolving 6 mmol of mandelic acid in 30mL of distilled water, adding 2 mmol of triethanolamine after complete dissolution, stirring to complete dissolution, and adding 1 mmol of prepared GdCl 3 Adding into the mixed solution, transferring the mixed solution into a 700W microwave oven, heating for 20min by microwave, cooling, filtering, discarding insoluble substances, dialyzing, purifying to obtain carbon doped points, and oven drying at 110deg.C to obtain brown nitrogen-gadolinium doped carbon points. The mass ratio of the carbon source, the nitrogen source and the gadolinium chloride is 6:2:1.
1 gram of the prepared nitrogen-gadolinium doped carbon dots are weighed and dissolved in 30mL of distilled water, 10 grams of diatomite is added, the mixture is reacted in a hydrothermal kettle at 200 ℃ for 2 hours, the mixture is filtered after washing, and the obtained solid is dried at 110 ℃ for 4 hours, so that the yellow nitrogen-gadolinium doped carbon dots-diatomite nanocomposite latent fingerprint developing powder is obtained. The particle size of the composite material is 2-20 microns, a classical powder visualization method is utilized, a fingerprint brush is used for slightly dipping the ground nitrogen-gadolinium doped carbon dot-diatomite nano composite material powder, fingerprints are brushed along the flow direction of fingerprint lines until the fingerprint lines of potential fingerprint samples are clearly presented, and ultraviolet 365nm or blue light 450nm light irradiation is used for excitation, so that green fluorescence is visible. The mastoid thread and its detailed features can be fixed with a digital camera or microscope.
Example 15 the material ratios and operating procedures were the same as in example 3, example 12, except that the amounts of carbon source, nitrogen source and gadolinium chloride materials used in example 15 were 6:2:1.
Example 15
The preparation method of the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder comprises the following specific operations:
dissolving 6 mmol of malic acid in 30mL of distilled water, adding 2 mmol of triethanolamine after complete dissolution, stirring to complete dissolution, and adding 1 mmol of prepared GdCl 3 Adding into the mixed solution, and transferring the mixed solution to a 700W microwave ovenHeating with medium microwave for 20min, cooling, filtering to remove insoluble substances, dialyzing, purifying to obtain carbon doped point, and oven drying at 110deg.C to obtain brown nitrogen-gadolinium doped carbon point. The mass ratio of the carbon source, the nitrogen source and the gadolinium chloride is 6:2:1.
1 gram of the prepared nitrogen-gadolinium doped carbon dots are weighed and dissolved in 30mL of distilled water, 10 grams of diatomite is added, the mixture is reacted in a hydrothermal kettle at 180 ℃ for 2 hours, the mixture is filtered after washing, and the obtained solid is dried at 110 ℃ for 4 hours, so that the yellow nitrogen-gadolinium doped carbon dots-diatomite nanocomposite latent fingerprint developing powder is obtained. The particle size of the composite material is 2-20 microns, a classical powder visualization method is utilized, a fingerprint brush is used for slightly dipping the ground nitrogen-gadolinium doped carbon dot-diatomite nano composite material powder, fingerprints are brushed along the flow direction of fingerprint lines until the fingerprint lines of potential fingerprint samples are clearly presented, and ultraviolet 365nm or blue light 450nm light irradiation is used for excitation, so that green fluorescence is visible. The mastoid thread and its detailed features can be fixed with a digital camera or microscope.
Example 16 the material ratios and operating procedures were the same as in example 1, example 10, example 13, except that the amounts of carbon source, nitrogen source and gadolinium chloride materials used in example 16 were 8:2:1.
Example 16
The preparation method of the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder comprises the following specific operations:
dissolving 6 mM lactic acid in 30mL distilled water, adding 1.5 mM triethanolamine, stirring to dissolve completely, and adding prepared 0.75 mM GdCl 3 Adding into the mixed solution, transferring the mixed solution into a 700W microwave oven, heating for 20min by microwave, cooling, filtering, discarding insoluble substances, dialyzing, purifying to obtain carbon doped points, and oven drying at 110deg.C to obtain brown nitrogen-gadolinium doped carbon points. The ratio of the amounts of the substances required for the carbon source, the nitrogen source and gadolinium chloride is 8:2:1.
1 gram of the prepared nitrogen-gadolinium doped carbon dots are weighed and dissolved in 30mL of distilled water, 10 grams of diatomite is added, the mixture is reacted in a hydrothermal kettle at 250 ℃ for 2 hours, the mixture is filtered after washing, and the obtained solid is dried at 110 ℃ for 4 hours, so that the yellow nitrogen-gadolinium doped carbon dots-diatomite nanocomposite latent fingerprint developing powder is obtained. The particle size of the composite material is 2-20 microns, a classical powder visualization method is utilized, a fingerprint brush is used for slightly dipping the ground nitrogen-gadolinium doped carbon dot-diatomite nano composite material powder, fingerprints are brushed along the flow direction of fingerprint lines until the fingerprint lines of potential fingerprint samples are clearly presented, and ultraviolet 365nm or blue light 450nm light irradiation is used for excitation, so that green fluorescence is visible. The mastoid thread and its detailed features can be fixed with a digital camera or microscope.
Example 17 the material ratios and operating procedures were the same as in example 2, example 11, example 14, except that the amounts of carbon source, nitrogen source and gadolinium chloride materials used in example 17 were 8:2:1.
Example 17
The preparation method of the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder comprises the following specific operations:
dissolving 6 mmol of mandelic acid in 30mL of distilled water, adding 1.5 mmol of triethanolamine after complete dissolution, stirring to complete dissolution, and adding 0.75 mmol of prepared GdCl 3 Adding into the mixed solution, transferring the mixed solution into a 700W microwave oven, heating for 20min by microwave, cooling, filtering, discarding insoluble substances, dialyzing, purifying to obtain carbon doped points, and oven drying at 110deg.C to obtain brown nitrogen-gadolinium doped carbon points. The mass ratio of the carbon source, the nitrogen source and the gadolinium chloride is 8:2:1.
1 gram of the prepared nitrogen-gadolinium doped carbon dots are weighed and dissolved in 30mL of distilled water, 10 grams of diatomite is added, the mixture is reacted in a hydrothermal kettle at 200 ℃ for 2 hours, the mixture is filtered after washing, and the obtained solid is dried at 110 ℃ for 4 hours, so that the yellow nitrogen-gadolinium doped carbon dots-diatomite nanocomposite latent fingerprint developing powder is obtained. The particle size of the composite material is 2-20 microns, a classical powder visualization method is utilized, a fingerprint brush is used for slightly dipping the ground nitrogen-gadolinium doped carbon dot-diatomite nano composite material powder, fingerprints are brushed along the flow direction of fingerprint lines until the fingerprint lines of potential fingerprint samples are clearly presented, and ultraviolet 365nm or blue light 450nm light irradiation is used for excitation, so that green fluorescence is visible. The mastoid thread and its detailed features can be fixed with a digital camera or microscope.
Example 18 the material ratios and operating procedures were the same as in example 3, example 12, example 15, except that the amounts of carbon source, nitrogen source and gadolinium chloride materials used in example 18 were 8:2:1.
Example 18
The preparation method of the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder comprises the following specific operations:
dissolving 6 mM malic acid in 30mL distilled water, adding 1.5 mM triethanolamine, stirring to dissolve completely, and adding prepared 0.75 mM GdCl 3 Adding into the mixed solution, transferring the mixed solution into a 700W microwave oven, heating for 20min by microwave, cooling, filtering, discarding insoluble substances, dialyzing, purifying to obtain carbon doped points, and oven drying at 110deg.C to obtain brown nitrogen-gadolinium doped carbon points. The mass ratio of the carbon source, the nitrogen source and the gadolinium chloride is 8:2:1.
1 gram of the prepared nitrogen-gadolinium doped carbon dots are weighed and dissolved in 30mL of distilled water, 10 grams of diatomite is added, the mixture is reacted in a hydrothermal kettle at 180 ℃ for 2 hours, the mixture is filtered after washing, and the obtained solid is dried at 110 ℃ for 4 hours, so that the yellow nitrogen-gadolinium doped carbon dots-diatomite nanocomposite latent fingerprint developing powder is obtained. The particle size of the composite material is 2-20 microns, a classical powder visualization method is utilized, a fingerprint brush is used for slightly dipping the ground nitrogen-gadolinium doped carbon dot-diatomite nano composite material powder, fingerprints are brushed along the flow direction of fingerprint lines until the fingerprint lines of potential fingerprint samples are clearly presented, and ultraviolet 365nm or blue light 450nm light irradiation is used for excitation, so that green fluorescence is visible. The mastoid thread and its detailed features can be fixed with a digital camera or 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, nitrogen sources and carbon source/nitrogen source/gadolinium chloride ratios are adopted, and the prepared carbon dot loadings are slightly different.
TABLE 1 materials, ratios and carbon Point loadings in examples 1-18
Under different materials and proportions, the carbon dots of the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite are adhered differently, but basically kept at 4% -5%, and can be uniformly dispersed on the surface of the matrix material, and as can be seen from Table 1, the carbon source, the nitrogen source and GdCl 3 The different proportions of the carbon loading determine the difference of the carbon loading, directly influence the adhesion condition of carbon points on the surface of the matrix and influence the final appearance effect of the latent fingerprint.
According to the embodiment of the invention, the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite with fluorescence is synthesized through simple microwaves, so that the problem of the size effect of carbon dots is solved, the good development performance of the composite is endowed, and the adaptability of the composite 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 fingerprints.
Claims (4)
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 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 points, and drying to obtain brown nitrogen-gadolinium doped carbon points; 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; the mass ratio of the carbon source, the nitrogen source and the gadolinium chloride is (1-10): 1-5): 1-2; the loading amount of the prepared carbon dots is 4% -5%;
dissolving the prepared nitrogen-gadolinium doped carbon dots in distilled water, adding matrix diatomite, wherein the mass ratio of the nitrogen-gadolinium doped carbon dots to the matrix diatomite is 1:10, 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, wherein the particle size of the composite is 2-20 microns, and green fluorescence can be seen under 365nm or 450nm light irradiation.
2. The method for preparing the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder according to claim 1, wherein the method comprises the steps of 3 The mixed solution is heated for 5-60 min in a 700W microwave oven.
3. The method for preparing the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder according to claim 1, wherein the prepared nitrogen-gadolinium doped carbon dot is dissolved in distilled water, and after adding matrix diatomite, the nitrogen-gadolinium doped carbon dot reacts in a hydrothermal reaction kettle at 180-250 ℃ for 1-2 h.
4. The preparation method of the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder according to claim 1, wherein the application of the nitrogen-gadolinium doped carbon dot-diatomite nanocomposite latent fingerprint developing powder in latent fingerprint imaging comprises the following steps:
step 1: preparation of latent oil sweat mixed fingerprint
Pressing the fingerprint on the surface of a carrier, transferring the oil sweat mixture on the finger to the surface of the carrier to form a fingerprint potential print, and further obtaining an oil sweat potential fingerprint sample; the latent fingerprint carrier is glass, metal, paper, plastic, food package, leather and ceramic;
step 2: powder visualization method for developing fingerprints
Dipping the prepared nano composite material developing powder by a fingerprint brush, brushing the developing powder on potential fingerprints left on the surface of a carrier, after the fingerprints are found, shaking out redundant developing powder, and continuing brushing out the redundant powder by the fingerprint brush along the flow direction of the fingerprints until the fingerprints of the fingerprint sample are clearly shown;
step 3: extracting fingerprints
The light source of 365nm or 450nm is selected to obliquely irradiate on the fingerprint lines after the appearance, a digital camera or a microscope is used for photographing and imaging, the visible fingerprints are green and emit light, and the purpose of fluorescent appearance of the latent fingerprints is achieved.
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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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