CN113185971B

CN113185971B - Manganese-based fluorescent fingerprint developing powder and preparation method and application thereof

Info

Publication number: CN113185971B
Application number: CN202110129992.8A
Authority: CN
Inventors: 彭迪; 张雨嫣
Original assignee: Southwest University Of Political Science & Law
Current assignee: Southwest University Of Political Science & Law
Priority date: 2021-01-29
Filing date: 2021-01-29
Publication date: 2023-03-21
Anticipated expiration: 2041-01-29
Also published as: CN113185971A

Abstract

The invention belongs to the field of material science and court science, and discloses manganese fluorescent fingerprint developing powder as well as a preparation method and application thereof. The structural formula of the developing powder is K ₃ AlF ₆ ：Mn ⁴⁺ -OA, which is prepared by: mixing Al (NO) ₃ ) ₃ ·9H ₂ Mixing O and HF solution, adding K ₂ MnF ₆ Adding KF, stirring and cooling; collecting the powder, washing for three times, and then placing the powder in a vacuum environment at the temperature of 55-85 ℃ for 2-4h to obtain K ₃ AlF ₆ ：Mn ⁴⁺ Fluorescent powder; mixing alcohol and oleic acid, K ₃ AlF ₆ ：Mn ⁴⁺ The fluorescent powder is loaded in an ultrasonic instrument for dispersing for 0.5 to 1.5h, then is heated in a water bath at the temperature of between 120 and 150 ℃ for 6h, is cooled and centrifuged, is washed by ethanol to remove redundant oleic acid products, and is dried at the temperature of between 55 and 70 ℃ for 5h to generate oleic acid passivated K ₃ AlF ₆ ：Mn ⁴⁺ -OA powder.The invention discloses a method for developing a latent fingerprint reagent, which comprises the following steps: 1) Will K ₃ AlF ₆ ：Mn ⁴⁺ Spreading OA on the fingerprint surface to display latent fingerprints on the object; 2) And (5) irradiating the handprint by blue light, and collecting a handprint image. The powder of the invention has the characteristics of high contrast, high sensitivity and high selectivity.

Description

Manganese-based fluorescent fingerprint developing powder and preparation method and application thereof

Technical Field

The invention relates to the field of material science and court science, in particular to manganese series fluorescent fingerprint developing powder and a preparation method and application thereof.

Background

Latent fingerprints are formed after sweat at the tail ends of fingers contacts with objects, and latent fingerprints of criminal suspects are often left on different objects in a crime scene. Because the fingerprints of each person are different and the lines are basically unchanged for life, the fingerprints have the characteristics of good specificity, stability, trace retention in touching objects and the like, and therefore the fingerprints play a very important role in the aspects of detecting the use of case handling and court evidence and the like. The personal identification of criminals through fingerprints is a favorable means for fighting against illegal crimes, and the fingerprints are known as evidence, so that the latent fingerprints are particularly important in the display and identification technology.

The traditional fingerprint developing and identifying method comprises optical development, common powder development, 502 fumigation development, ninhydrin compound development and the like, and the fingerprint developing method is simple and easy to implement, but has the problems of low sensitivity, low contrast, harm to the body of on-site surveyors and the like, so that the extraction and identification of the latent fingerprints are difficult, and a good effect is difficult to obtain in the latent fingerprint development of difficult objects, so that the fingerprint developing method needs to be deeply explored in the field to overcome the difficulties.

With the development of science and technology, emerging noble metal nanoclusters, rare earth fluorescent powder visualization methods and the like are valued by people due to good sensitivity and selectivity, and particularly rare earth nano fluorescent powder has the characteristics of excellent luminous intensity, rich optical properties and the like, is gradually applied to a latent fingerprint visualization technology and plays an irreplaceable role. However, the rare earth nano fluorescent powder display method still has the defects of complex reagent preparation, easy pollution, high price and the like, and the rare earth fluorescent powder excited by ultraviolet light is easily interfered by background color of a substrate and strong background autofluorescence, so that the application in the aspect of latent fingerprint display is limited.

Compared with the traditional non-luminous latent fingerprint display and identification method, the luminous material has the optical characteristics of good light stability, high fluorescence intensity and the like, the small luminous material is used for displaying the latent fingerprint, the method is a simple, convenient, non-toxic and nondestructive display method, but the luminous material is still used in the field of latent fingerprint detection, and the effect of displaying the latent fingerprint through fluorescence enhancement needs to be further explored. Therefore, the field needs to further research the luminescent material in order to further develop the latent fingerprint luminescence detection technology, so as to obtain the clearest result, provide an idea for field investigation, and provide a clue for investigation of a case.

Disclosure of Invention

The invention aims to make up the defects of the prior art and provides manganese series fluorescent fingerprint developing powder and a preparation method and application thereof, wherein the manganese series fluorescent fingerprint developing powder has uniform superfine morphology and excellent luminescence property, and has the characteristics of high contrast, high sensitivity and high selectivity; after the fingerprints are displayed, the less disturbing and clear ridge-shaped details of different surface backgrounds such as a single-color background substrate, a multi-color background substrate and a powder display autofluorescence background can be given in a few seconds.

The technical scheme adopted for achieving the purpose of the invention is as follows:

manganese series fluorescent fingerprint developing powder with the structural formula of K ₃ AlF ₆ ：Mn ⁴⁺ -OA, the particle size of the manganese series fluorescent fingerprint developing powder is 300-350nm.

A preparation method of manganese series fluorescent fingerprint developing powder comprises the following steps:

s1, preparation K ₃ AlF ₆ ：Mn ⁴⁺ Fluorescent powder

S101, al (NO) is firstly added ₃ ) ₃ ·9H ₂ Mixing O and HF solution, adding K ₂ MnF ₆ Stirring for 5min until the solution is completely dissolved to obtain a solution A;

s102, adding KF into the solution A, stirring for 30min, and cooling;

s103, collecting light yellow powder, and sequentially and respectively washing the light yellow powder with acetic acid and absolute ethyl alcohol for three times to obtain powder B;

s104, placing the powder B in a vacuum environment at the temperature of 55-85 ℃ for 2-4h to obtain K ₃ AlF ₆ ：Mn ⁴⁺ Fluorescent powder;

s2, preparation K ₃ AlF ₆ ：Mn ⁴⁺ -OA phosphor

S201, mixing alcohol and oleic acid, and adding K prepared in the step S1 ₃ AlF ₆ ：Mn ⁴⁺ Fluorescent powder to obtain a solution C;

s202, dispersing the solution C in an ultrasonic instrument for 0.5-1.5h, and heating in a water bath at 120-150 ℃ for 6h to obtain a mixture D;

s203, cooling and centrifuging the mixture D, washing the mixture D with ethanol to remove excessive oleic acid products, and drying the mixture D at the temperature of between 55 and 70 ℃ for 5 hours to generate oleic acid passivated K ₃ AlF ₆ ：Mn ⁴⁺ -OA powder.

The method for applying manganese series fluorescent fingerprint developing powder as a latent fingerprint developing reagent comprises the following steps:

1) Will K ₃ AlF ₆ ：Mn ⁴⁺ Uniformly spreading OA on the fingerprint surface to display latent fingerprints on the object;

2) And (4) irradiating the developed handprint by using blue light, then shooting by using a digital camera, and collecting the image of the handprint.

The fluorescent powder is used for visualizing the latent fingerprints, is a simple, convenient and effective method, sweat and grease in the latent fingerprint deposits have certain adsorption capacity, when the fluorescent powder is attached to the surface of a bearing object, the powder and the fingerprint deposits generate strong affinity action, and after fingerprint lines are printed, the fingerprints are irradiated by light with certain wavelength, so that the lines of the latent fingerprints can be displayed very clearly. The latent fingerprint displayed by the rare earth fluorescent powder has the characteristics of high contrast, high quality and high-intensity fluorescence. In the present invention, in the case of the present invention, ₃ ₆ ⁴⁺ ₃ ₆ ⁴⁺ oleic acid as a surfactant for KAlF Mn, to produce oleic acid-deactivated KAlF: mn-OA powder being hydrophobic Property of (2)And converting hydrophobicity into hydrophilic fluorescent powder to be applied to latent fingerprint visualization. AFIS system evaluation shows that the secondary feature recognition rate of the method is higher than that of the traditional display method, because of Mn ⁴⁺ Doped fluorides with low cost, high compatibility and good usabilityHas the advantage of quickly detecting potential fingerprints, and has wide application prospect as a substitute of luminescent materials in the fields of forensic medicine and the like.

The invention has the beneficial effects that:

(1) The manganese series fluorescent fingerprint developing powder has high sensitivity, high contrast, uniform superfine morphology and excellent luminescence property;

(2) The invention adopts non-Ultraviolet (UV) or non-Near Infrared (NIR) induced fluorescent material as an ideal fluorescent marker for potential fingerprint imaging, which is not only beneficial to touch DNA analysis, but also compatible with a forensic light source, and can avoid autofluorescence interference of part of objects caused by a universal UV light source;

(3) The luminous detection technology can effectively identify potential fingerprints on different objects, and has the characteristics of high contrast, high sensitivity and high selectivity;

(4) K modified with oleic acid by powder development ₃ AlF ₆ ：Mn ⁴⁺ The method not only can overcome the defect that the moisture of manganese fluoride fluorescent powder causes fluorescence quenching, but also can enhance the interaction between the powder and the grease component in fingerprint residues, is beneficial to the development effect of old fingerprints, and can provide clear ridge-shaped details with smaller interference under different surface backgrounds such as a single-color background substrate, a multi-color background substrate, a powder display method autofluorescence background and the like in a few seconds;

(5) The raw materials of the invention are all chemical raw materials, are cheap and easily available, have simple materials and are suitable for industrial production mode.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.

FIG. 1 shows different Mn ⁴⁺ K at doping concentration ₃ AlF ₆ XRD analysis pattern of (a);

FIG. 2 is K ₃ AlF ₆ :Mn ⁴⁺ Schematic diagram of crystal structure scheme of phosphor;

FIG. 3 is a diagram of five different octahedra [ AlF ] in the crystal structure ₆ ]A schematic diagram;

FIG. 4 is K ₃ AlF ₆ ：Mn ⁴⁺ -scanning electron microscope images of samples of OA;

FIG. 5 shows K ₃ AlF ₆ ：Mn ⁴⁺ -size distribution of TEM images of OA samples;

FIG. 6 shows K ₃ AlF ₆ ：Mn ⁴⁺ -transmission electron microscopy images of OA phosphors;

FIG. 7 is K ₃ AlF ₆ ：Mn ⁴⁺ -OA phosphor K ₃ AlF ₆ ：Mn ⁴⁺ And OA, schematic representation of the binding properties;

FIG. 8 is K ₃ AlF ₆ ：Mn ⁴⁺ And K ₃ AlF ₆ ：Mn ⁴⁺ -diffuse reflectance spectrum of OA phosphor;

FIG. 9 is K ₃ AlF ₆ ：Mn ⁴⁺ And K ₃ AlF ₆ ：Mn ⁴⁺ -spectrum and pl plot of OA phosphor;

FIG. 10 shows Mn ⁴⁺ Doped K ₃ AlF ₆ ：Mn ⁴⁺ A spectrogram of the fluorescent powder under 468nm excitation;

FIG. 11 is K ₃ AlF ₆ ：Mn ⁴⁺ And K ₃ AlF ₆ ：Mn ⁴⁺ -spectra (em =629 nm) and pl (ex =468 nm) of OA phosphors;

FIG. 12 is K ₃ AlF ₆ ：Mn ⁴⁺ And K ₃ AlF ₆ ：Mn ⁴⁺ -fi-ir spectrum of OA phosphor;

FIG. 13 shows excited K ₃ AlF ₆ ：Mn ⁴⁺ The luminous attenuation curve of the fluorescent powder is a diagram of 468 nm;

FIG. 14 shows a schematic representation of a graph formed by K ₃ AlF ₆ ：Mn ⁴⁺ Schematic representation of latent fingerprint detection with OA phosphor;

FIG. 15 is a schematic representation of the imaging of a latent fingerprint of a cyanoacrylate on a surface;

FIG. 16 is a schematic representation of the imaging of a latent fingerprint of a cyanoacrylate on a surface;

FIG. 17 is a schematic representation of the imaging of a latent fingerprint of a cyanoacrylate on another surface;

FIG. 18 is a schematic view of imaging a latent fingerprint of a bright-field ferromagnetic powder on a surface;

FIG. 19 is a schematic representation of imaging of latent fingerprints of bright field ferromagnetic powder on a surface;

FIG. 20 is a schematic representation of imaging of latent fingerprints of bright field ferromagnetic powder on another surface;

FIG. 21 is a schematic representation of imaging of 312nm illuminated latent fingerprints in a surface with bright and dark fields using commercial red phosphors;

FIG. 22 is a schematic representation of imaging of 312nm illuminated latent fingerprints in a surface with bright and dark fields using commercial red phosphors;

FIG. 23 is a schematic illustration of imaging of a 312nm illuminated latent fingerprint with a dark field in a surface using a commercial red phosphor;

FIG. 24 is K ₃ AlF ₆ ：Mn ⁴⁺ Schematic representation of imaging of 445-485nm illuminated latent fingerprints with bright and dark fields by OA phosphors in a certain surface;

FIG. 25 shows K ₃ AlF ₆ ：Mn ⁴⁺ Schematic representation of imaging of 445-485nm illuminated latent fingerprints with bright and dark fields by OA phosphors in a surface;

FIG. 26 is K ₃ AlF ₆ ：Mn ⁴⁺ Schematic representation of latent fingerprints with 312nm secondary illumination of OA phosphors in a dark field in a certain surface;

FIG. 27 is an image of a latent fingerprint marked with cyanoacrylate with a printed pattern as a substrate;

FIG. 28 is an image of a latent fingerprint marked with a printed pattern as a substrate with or ferromagnetic powder;

FIG. 29 is an image of a latent fingerprint marked with ferromagnetic powder using painted wood as the substrate;

FIG. 30 is an image of a latent fingerprint marked with ferromagnetic powder using painted wood as the substrate;

FIG. 31 shows a case where a printed pattern is used as a base K ₃ AlF ₆ ：Mn ⁴⁺ -an image of latent fingerprints of OA powder markings;

FIG. 32 shows a case where a printed pattern is used as a base K ₃ AlF ₆ ：Mn ⁴⁺ -another latent fingerprint image of OA powder markings;

FIG. 33 shows a K used for painting wood as a substrate ₃ AlF ₆ ：Mn ⁴⁺ -an image of latent fingerprints of OA powder markings;

FIG. 34 shows a K used for painting wood as a substrate ₃ AlF ₆ ：Mn ⁴⁺ -another latent fingerprint image of OA powder markings;

FIG. 35 is an image of commercial phosphor on a bright field with RMB as the substrate;

FIG. 36 is an image of inspection of FIG. 35 with RMB as the substrate and dark field illumination with light of 312nm wavelength;

FIG. 37 shows a view of a case where RMB is used as a substrate K ₃ AlF ₆ ：Mn ⁴⁺ -images of OA phosphors in bright field;

FIG. 38 is an image of FIG. 37 detected by illumination of the dark field with 445-485nm wavelength light using RMB as the substrate.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

Manganese series fluorescent fingerprint developing powder with the structural formula of K ₃ AlF ₆ ：Mn ⁴⁺ -OA, the particle size of the manganese series fluorescent fingerprint developing powder is 300nm.

s1, preparation K ₃ AlF ₆ ：Mn ⁴⁺ Fluorescent powder

s102, adding KF into the solution A, stirring for 30min, and cooling;

s104, placing the powder B in a vacuum environment at 55 ℃ for 2h to obtain K ₃ AlF ₆ ：Mn ⁴⁺ Fluorescent powder;

s2, preparation K ₃ AlF ₆ ：Mn ⁴⁺ -OA phosphor

s202, placing the solution C in an ultrasonic instrument for dispersing for 0.5h, and heating in a water bath at 130 ℃ for 6h to obtain a mixture D;

s203, cooling and centrifuging the mixture D, washing the mixture D with ethanol to remove excessive oleic acid products, and drying the mixture D for 5 hours at 55 ℃ to generate oleic acid passivated K ₃ AlF ₆ ：Mn ⁴⁺ -OA powder.

Further, in step S101, al (NO) is added ₃ ) ₃ ·9H ₂ And stirring the O solution and the HF solution for 20min by adopting strong magnetism when mixing.

Further, the cooling manner in step S102 is to quickly place the container into an ice-water bath for cooling for 1 hour after the stirring is finished. After the stirring is finished, the container is quickly placed into an ice water bath for cooling for 1h, so that the valence state change of tetravalent manganese ions is avoided, and the volatilization of toxic HF is reduced.

The method for applying the manganese fluorescent fingerprint developing powder as a latent fingerprint developing reagent comprises the following steps:

Further, the latent fingerprints in the step 1) are displayed by adopting a powder brush display method.

Further, in step 2), the blue light wavelength is 445nm.

Example 2

Manganese series fluorescent fingerprint developing powder with the structural formula of K ₃ AlF ₆ ：Mn ⁴⁺ -OA, the particle size of the manganese-based fluorescent fingerprint developing powder is 324nm.

s1, preparation K ₃ AlF ₆ ：Mn ⁴⁺ Fluorescent powder

S101, firstly Al (NO) ₃ ) ₃ ·9H ₂ Mixing the O and HF solution, and adding K ₂ MnF ₆ Stirring for 5min until the solution is completely dissolved to obtain a solution A;

s102, adding KF into the solution A, stirring for 30min, and cooling;

s104, placing the powder B in a vacuum environment with the optimal temperature of 70 ℃ for 3h to obtain K ₃ AlF ₆ ：Mn ⁴⁺ Fluorescent powder;

s2, preparation K ₃ AlF ₆ ：Mn ⁴⁺ -OA phosphor

s202, dispersing the solution C in an ultrasonic instrument for 1h, and heating in a water bath at the temperature of 140 ℃ for 6h to obtain a mixture D;

s203, cooling and centrifuging the mixture D, washing the mixture D with ethanol to remove excessive oleic acid products, and drying the mixture D for 5 hours at the temperature of 60 ℃ to generate oleic acid passivated K ₃ AlF ₆ ：Mn ⁴⁺ -OA powder.

Further, the cooling method in step S102 is to quickly place the container in an ice-water bath for cooling for 1 hour after the stirring is finished. After the stirring is finished, the container is quickly placed into an ice water bath for cooling for 1h, so that the valence state change of tetravalent manganese ions is avoided, and the volatilization of toxic HF is reduced.

2) And (4) irradiating the developed handprint by using blue light, then shooting by using a digital camera, and collecting a handprint image.

Further, in step 2), the blue light wavelength is 468nm.

Example 3

Manganese series fluorescent fingerprint developing powder with the structural formula of K ₃ AlF ₆ ：Mn ⁴⁺ -OA, the particle size of the manganese-based fluorescent fingerprint developing powder is 350nm.

s1, preparation K ₃ AlF ₆ ：Mn ⁴⁺ Fluorescent powder

S101, firstly Al (NO) ₃ ) ₃ ·9H ₂ Mixing O and HF solution, adding K ₂ MnF ₆ Stirring for 5min until the solution is completely dissolved to obtain a solution A;

s102, adding KF into the solution A, stirring for 30min, and cooling;

s104, placing the powder B in a vacuum environment at 85 ℃ for 4h to obtain K ₃ AlF ₆ ：Mn ⁴⁺ Fluorescent powder;

s2, preparation K ₃ AlF ₆ ：Mn ⁴⁺ -OA phosphor

s202, placing the solution C in an ultrasonic instrument for dispersing for 1.5h, and heating in a water bath at 150 ℃ for 6h to obtain a mixture D;

s203, cooling and centrifuging the mixture D, washing the mixture D with ethanol to remove excessive oleic acid products, and drying the mixture D for 5 hours at 70 ℃ to generate oleic acid passivated K ₃ AlF ₆ ：Mn ⁴⁺ -OA powder.

Further, in the step 2), the blue light wavelength is 485nm.

Examples

Firstly, the method comprises the following steps: k ₃ AlF ₆ :Mn ⁴⁺ Preparation of

1. Preparation of materials and apparatus

All materials required by the product manufacture comprise: h ₂ O ₂ (30wt.％)、KMnO ₄ (A.R.)、KF(99.9％)、KHF ₂ (99.5％)、Al(NO ₃ ) ₃ ·9H ₂ O (99.99%), HF (48 wt.%), acetic acid (HAC), oleic acid (a.r.), and absolute ethanol (a.r.), all of which were used without further purification after direct purchase.

Wherein Al (NO) ₃ ) ₃ ·9H ₂ O、HF、KF、KHF ₂ And oleic acid were provided by Shanghai Aladdin Biochemical technology Ltd (China), and the rest were KMnO4, absolute ethanol, H ₂ O ₂ ) Purchased from Guangdong Xilong science, inc. (China).

2. Preparation process

(1) Preparation K ₃ AlF ₆ ：Mn ⁴⁺ Fluorescent powder

Weighing 6mmol Al (NO) ₃ ) ₃ ·9H ₂ O (2.2508 g) was added to a 25mL polytetrafluoroethylene beaker containing 8mL of HF solution, and after stirring with strong magnetism for 20min, 0.18mmol K was added ₂ MnF ₆ (0.0445 g) was poured into the above solution and stirred for 5min until complete dissolution.

Then, 126mmol KF (7.3206 g) was added to the above mixed solution, and the mixed solution was further stirred for 30min. Then the polytetrafluoroethylene beaker is quickly placed in an ice-water bath for 1h, so as to avoid the valence state change of tetravalent manganese ions and reduce the volatilization of toxic HF.

The collected pale yellow powder was washed three times with acetic acid and then with anhydrous ethanol. Finally, they were subjected to a vacuum environment at 70 ℃ for 3h to obtain the final product.

(2) Preparation K ₃ AlF ₆ ：Mn ⁴⁺ -OA phosphor

First, a mixed solution was prepared by adding 2.5ml of oleic acid to a Teflon test tube containing 12.5ml of ethanol, and then 0.5g of K was added ₃ AlF ₆ ：Mn ⁴⁺ And (3) fluorescent powder.

Then, the phosphor was completely dispersed with 1 hour of ultrasound, and the dispersed solution was heated in a water bath at 140 ℃ for 6 hours.

After the reaction, the mixture was allowed to cool and centrifugedWashing with ethanol repeatedly to remove excessive oleic acid product, and drying at 60 deg.C for 5 hr to obtain oleic acid-passivated K ₃ AlF ₆ ：Mn ⁴⁺ -OA powder.

II, secondly: k ₃ AlF ₆ ：Mn ⁴⁺ Is characterized by

1、K ₃ AlF ₆ ：Mn ⁴⁺ Spectrum and crystal structure of

As shown in FIG. 1, for different Mn ⁴⁺ Doping concentration K ₃ AlF ₆ XRD analysis was performed to simulate K ₃ AlF ₆ And standard K ₃ AlF ₆ And the phase purity of the synthetic samples was examined with CuK alpha radiation (λ = 1.5418A) on a bruker type 8 ADVANCED powder X-ray diffractometer from 10 ° to 90 ° in the range of 40kV and 40 mA. The microstructure and elemental analysis were studied using a FEIQuanta200 thermal finite element environment scanning electron microscope and a JEOL-2010 Transmission Electron Microscope (TEM) equipped with Selected Area Electron Diffraction (SAED). The ultraviolet-visible Diffuse Reflectance Spectrum (DRS) was measured using an ultraviolet-visible-near infrared spectrometer with barium sulfate as a standard reference. Photoluminescence (PL) spectra, photoluminescence excitation (PLE), quantum Yield (QY) and PL decay curves of a 450W xenon light source were measured with a fluorescence spectrometer at room temperature.

K ₃ AlF ₆ The compounds having four crystal phases, i.e. alpha-K ₃ AlF ₆ (stable between room temperature and 132 ℃), beta-K ₃ AlF ₆ (stable between 132 ℃ and 153 ℃), gamma-K ₃ AlF ₆ (stable between 153 ℃ and 306 ℃), delta-K ₃ AlF ₆ (stable above 306 ℃). As can be seen from FIG. 1, the experimental diffraction peaks and delta-K ₃ AlF ₆ The standard XRD patterns are well matched.

Inputting a Crystallography Information File (CIF) into Diamond software or VESTA software for modeling, and drawing alpha-K ₃ AlF ₆ Fig. 2-3, wherein the crystallography information file contains detailed information of each crystal, such as unit cell parameters, atomic coordinates, literature data, etc. Specifically, FIG. 2 isK ₃ AlF ₆ :Mn ⁴⁺ Schematic diagram of crystal structure scheme of phosphor; FIG. 3 shows five different octahedra [ AlF ] in the crystal structure ₆ ]Schematic representation. In the above structure, there are five different kinds of crystalline Al ³⁺ (expressed as Al 1-5) which are centered on five different distorted octahedra [ AlF ₆ ]. After modeling is completed, five distorted octahedrons [ AlF ] are calculated by using Diamond software or VESTA software ₆ ]Average Al of (2) ³⁺ F ^- Distances of 1.8121 (Al 1), 1.8137 (Al 2), 1.8167 (Al 3), 1.8357 (Al 4) and 1.7924 (Al 5), respectively. In addition, all twisted [ AlF ₆ ]The octahedra are isolated from each other in this structure. Due to Mn ⁴⁺ (r = 0.540A) and Al ³⁺ (r = 0.535A) similar effective ionic radii at six coordination numbers, mn ⁴⁺ Ions tend to replace Al ³⁺ Bit at alpha-K ₃ AlF ₆ ：Mn ⁴⁺ Form of [ MnF ] ₆ ] ^2- Red emitting octahedra.

2、K ₃ AlF ₆ ：Mn ⁴⁺ Morphological characterization of OA

The inorganic powder coated with organic oleic acid effectively enhances the interaction between the powder coated on the skin and sweat glands, and in general, ultrafine particles having a regular and uniform size adhere better to fingerprint residues than large particles having an irregular or non-uniform size. FIG. 4-FIG. 7 are K ₃ AlF ₆ ：Mn ⁴⁺ TEM image of OA sample, where K is FIG. 4 ₃ AlF ₆ ：Mn ⁴⁺ -scanning electron microscope images of OA samples; FIG. 5 is K ₃ AlF ₆ ：Mn ⁴⁺ -size distribution of TEM images of OA samples; FIG. 6 is K ₃ AlF ₆ ：Mn ⁴⁺ -transmission electron microscopy images of OA phosphors; FIG. 7 is K ₃ AlF ₆ ：Mn ⁴⁺ -OA phosphor K ₃ AlF ₆ ：Mn ⁴⁺ Schematic representation of the binding Properties between OA and OA (K) ₃ AlF ₆ ：Mn ⁴⁺ K, al and F in (a) and shell elements (c, o and h) are represented as light purple, yellow, blue, gray, red and white spheres, respectively). As can be seen from FIGS. 4 to 7, the synthesized product showed a uniform size distributionTetragonal features around 324nm are suitable for attaching fingerprint residues to observe detailed fingerprint features with high sensitivity.

3、K ₃ AlF ₆ ：Mn ⁴⁺ Optical characterization of OA

FIG. 8-FIG. 13 is K ₃ AlF ₆ ：Mn ⁴⁺ Optical characterization of OA, FIG. 8K ₃ AlF ₆ ：Mn ⁴⁺ And K ₃ AlF ₆ ：Mn ⁴⁺ -diffuse reflectance spectrum of OA phosphor; FIG. 9 is K ₃ AlF ₆ ：Mn ⁴⁺ And K ₃ AlF ₆ ：Mn ⁴⁺ Spectrograms of OA phosphors (em =629 nm) and pl (ex =468 nm); FIG. 10 shows Mn ⁴⁺ Doped K ₃ AlF ₆ ：Mn ⁴⁺ Spectrum of the fluorescent powder under 468nm excitation; FIG. 11 is K ₃ AlF ₆ ：Mn ⁴⁺ And K ₃ AlF ₆ ：Mn ⁴⁺ Spectrum of OA phosphor (em =629 nm) and pl (ex =468 nm); FIG. 12 is K ₃ AlF ₆ ：Mn ⁴⁺ And K ₃ AlF ₆ ：Mn ⁴⁺ -FI-IR spectrum of OA phosphor; FIG. 13 excited K ₃ AlF ₆ ：Mn ⁴⁺ The luminescence attenuation curve of the fluorescent powder is 468nm. As can be seen from FIGS. 8-13, K is different from most of the down-conversion luminescent lanthanide series materials ₃ AlF ₆ ：Mn ⁴⁺ The OA fluorescent powder has a wide absorption band near 468nm, and provides the potential for fingerprint imaging without background interference and touch DNA damage. It can be seen that under 468nm excitation, there are several sharp emission peaks from 590 to 660nm, which are assigned to Mn ⁴⁺ Is/are as follows ² E _g → ⁴ A _2g . Correspondingly, when synthesized K ₃ AlF ₆ ：Mn ⁴⁺ When the fluorescent powder is monitored at 629nm, two wide excitation bands reach peak values at 468nm and 362nm respectively, which are respectively from spin allowance ⁴ A _2g → ⁴ T _2g And ⁴ A _2g → ⁴ T _1g mn in the shell ⁴⁺ Is detected. Notably, the blue excitation region centered at 468nm is much higher than the uv excitation region (362 nm), which is consistent with the results of DRS. FIG. 10 shows different Mn ⁴⁺ The activation property of the phosphor with doping concentration. All spectra have the same characteristics except for emission intensity. Obviously, K ₃ AlF ₆ ：Mn ⁴⁺ The luminescence intensity of (a) increases first, reaches a maximum when the doping concentration is 7%, and then decreases, which is associated with concentration quenching.

As shown in FIG. 11, at K ₃ AlF ₆ ：Mn ⁴⁺ Coating oleic acid on the basis of the optimal doping amount of the fluorescent powder to prepare K ₃ AlF ₆ ：Mn ⁴⁺ -OA. The position and peak shape of the PL (λ ex =468 nm) and PLE (λ em =629 nm) spectra and K ₃ AlF ₆ ：Mn ⁴⁺ The same indicates that the surface organic layer does not change the spectral properties.

In summary, K ₃ AlF ₆ ：Mn ⁴⁺ the-OA fluorescent powder contains blue light induced red fluorescence, is sensitive to human naked eyes, and can be used for fingerprint display with high contrast and low background interference.

Thirdly, the method comprises the following steps: k ₃ AlF ₆ ：Mn ⁴⁺ Revealing latent fingerprints

The implementation method comprises the following steps: the latent fingerprint is displayed by a powder brushing method, and an operator needs to wear a mask to prevent powder from being inhaled in the displaying process. To verify K ₃ AlF ₆ ：Mn ⁴⁺ OA as a high contrast of the fluorescent marker of the potential fingerprint, a monochromatic, polychromatic and autofluorescent background substrate was chosen as a control, and the fingerprint image was presented under blue light illumination and then taken with a digital camera.

As shown in fig. 14, the specific powder rendering method:

dipping a little product by a geranium brush, flicking a brush handle to uniformly spread the powder on the surface of the fingerprint, then sweeping up and down along the vertical plane until the powder is completely adhered to the surface of the fingerprint, then sweeping away the redundant powder along the direction of the fingerprint lines, and then continuing to brush until the fingerprint lines are clear.

1. High sensitivity and selectivity investigation

Selecting a glass slide as a mark bearing object of the latent fingerprint, using cyanoacrylate, ferromagnetic powder and commercial red fluorescent powder as contrast, and using different reagentsImaging latent fingerprints on different surfaces is shown in FIGS. 15-26, wherein FIG. 15 is a schematic representation of the imaging of a latent fingerprint on a surface of a cyanoacrylate; FIG. 16 is a schematic representation of the imaging of a latent fingerprint of a cyanoacrylate on a surface; FIG. 17 is a schematic representation of the imaging of a latent fingerprint of a cyanoacrylate on another surface; FIG. 18 is a schematic view of imaging a latent fingerprint of a bright-field ferromagnetic powder on a surface; FIG. 19 is a schematic representation of imaging of latent fingerprints of bright field ferromagnetic powder on a surface; FIG. 20 is a schematic representation of imaging of latent fingerprints of bright field ferromagnetic powder on another surface; FIG. 21 is a schematic representation of imaging of 312nm illuminated latent fingerprints in a surface with bright and dark fields using commercial red phosphors; FIG. 22 is a schematic representation of imaging of 312nm illuminated latent fingerprints in a surface with bright and dark fields using commercial red phosphors; FIG. 23 is a schematic illustration of imaging of a 312nm illuminated latent fingerprint with a dark field in a surface using a commercial red phosphor; FIG. 24 is K ₃ AlF ₆ ：Mn ⁴⁺ Schematic representation of imaging of 445-485nm illuminated latent fingerprints with bright and dark fields by OA phosphors in a certain surface; FIG. 25 shows K ₃ AlF ₆ ：Mn ⁴⁺ Schematic representation of imaging of 445-485nm illuminated latent fingerprints with bright and dark fields by OA phosphors in a surface; FIG. 26 is K ₃ AlF ₆ ：Mn ⁴⁺ Schematic representation of the imaging of 312nm illuminated latent fingerprints with dark field in certain surface by OA phosphor.

2. High contrast verification in a multi-color background

Painted wood and printed patterns were selected as substrates and images marked with cyanoacrylate or ferromagnetic powder were shown in fig. 27-30, with latent fingerprints having lower contrast and background interference. On the contrary, when K is used ₃ AlF ₆ ：Mn ⁴⁺ When OA is observed, strong red fluorescence and color contrast in the substrate are obvious, which indicates K ₃ AlF ₆ ：Mn ⁴⁺ the-OA can significantly improve the background color interference of latent fingerprint imaging on multi-color background substrates, as shown in particular in fig. 31-34.

3、K ₃ AlF ₆ ：Mn ⁴⁺ Verification of OA resistance to autofluorescence

FIG. 35-FIG. 38 are K ₃ AlF ₆ ：Mn ⁴⁺ FIG. 35-38 show that, when Renminbi was chosen as the substrate, the commercial red phosphor labeled papillary ridges were severely blurred due to yellow autofluorescence of the substrate under UV excitation at 312nm, while K is K, as can be seen in FIGS. 35-38 ₃ AlF ₆ ：Mn ⁴⁺ Fingerprints of OA marks show clear ridge details and low background interference under blue illumination (fig. 38). Thus, K ₃ AlF ₆ ：Mn ⁴⁺ OA can effectively avoid interference from autofluorescence and produce high contrast on various substrates.

The above-mentioned embodiments are further described in detail for the purpose of illustrating the invention, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the invention and are not intended to limit the invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit of the invention should be included in the scope of the invention.

Claims

1. The manganese series fluorescent fingerprint developing powder is characterized in that the structural formula is K ₃ AlF ₆ ：Mn ⁴⁺ -OA, the particle size of the manganese series fluorescent fingerprint developing powder is 300-350nm.

2. The method for preparing manganese-based fluorescent fingerprint developing powder according to claim 1, comprising the steps of:

s1, preparation K ₃ AlF ₆ ：Mn ⁴⁺ Fluorescent powder

s102, adding KF into the solution A, stirring for 30min, and cooling;

s104, placing the powder B inObtaining K under vacuum environment at 55-85 ℃ for 2-4h ₃ AlF ₆ ：Mn ⁴⁺ A fluorescent powder;

s2, preparation K ₃ AlF ₆ ：Mn ⁴⁺ -OA phosphor

s203, cooling and centrifuging the mixture D, washing the mixture D with ethanol to remove excessive oleic acid products, and drying the mixture D at the temperature of between 55 and 70 ℃ for 5 hours, wherein the oleic acid is used as K ₃ AlF ₆ :Mn ⁴⁺ To oleic acid-deactivated K ₃ AlF ₆ ：Mn ⁴⁺ -OA powder.

3. The method for preparing manganese-based fluorescent fingerprint developing powder according to claim 2, wherein Al (NO) is added in step S101 ₃ ) ₃ ·9H ₂ And stirring the O solution and the HF solution for 20min by adopting strong magnetism when mixing.

4. The method for preparing manganese-based fluorescent fingerprint developing powder according to claim 2, wherein the cooling manner in step S102 is to rapidly put the container into an ice-water bath for cooling for 1 hour after the stirring is finished.

5. The method for applying manganese-based fluorescent fingerprint developing powder as defined in claim 1 as a latent fingerprint developing agent, comprising the steps of:

6. The method for applying manganese-based fluorescent fingerprint developing powder as a latent fingerprint developing agent according to claim 5, wherein the latent fingerprint developing in step 1) is performed by a powder printing method.

7. The method for applying manganese-based fluorescent fingerprint developing powder as a latent fingerprint developing agent according to claim 5, wherein in step 2), the blue light wavelength range is 445 to 485nm.