CN101582183B

CN101582183B - Method for inspecting paper currency

Info

Publication number: CN101582183B
Application number: CN2009100402085A
Authority: CN
Inventors: 胡孙林; 戴维列; 张小婷; 王松才; 沈辉
Original assignee: GUANGZHOU CITY FORENSIC SCIENCE TECHNOLOGY INSTITUTE
Current assignee: GUANGZHOU CITY FORENSIC SCIENCE TECHNOLOGY INSTITUTE
Priority date: 2009-06-12
Filing date: 2009-06-12
Publication date: 2010-12-01
Anticipated expiration: 2029-06-12
Also published as: CN101582183A

Abstract

The invention belongs to the field of material evidence inspection, in particular relates to a method for inspecting paper currency, and uses micro beam XPF to perform non-destructive analysis on an experiment sample. Under the incident micro beam X-ray, a computer software scans a sample by automatically controlling the sample to move continually; characteristic X-ray photons excited by each scanpoint enter an energy detector, and form a spectrum by being processed through an amplifier and a multichannel analyzer; and a two-dimension element scattergram of the sample is obtained after scanning. Finally, the distribution characteristics of element surfaces of a sample paper currency and a known paper currency are compared to obtain an analysis result. The method has the characteristics ofno loss, high sensitivity, accurate result and the like, and has excellent application prospect.

Description

A kind ofly dyed the black bank note method of inspection

Technical field

The invention belongs to the examination of material evidence field, particularly a kind ofly dyed the black bank note method of inspection.

Background technology

In recent years, a kind of utilization occurs and dyed the criminal case that black true and false bank note (" black bank note ") is swindled.The suspect is dyed black true bank note by demonstration with the chemical reagent recovery and is gained victim's trust by cheating, then to instigate the victim to buy chemical reagent or to dye black modes such as counterfeit money and defraud of money.Such case is usually because of the case-involving amount of money is big, the suspicion of crime people causes considerable influence socially for foreign personage.

In this class case, " black bank note " is the crucial material evidence that confirms crime, thereby need carry out scientific verification.Yet since paper material by dyestuff dye black after, variation has taken place in physicochemical property, traditional bank note optical characteristics discriminating means such as Ultraluminescence spectroscopic methodology, IR transmission method, reflection method etc. can't be tested to " black bank note " material evidence, and do not see the report that the related check technology is arranged as yet in the domestic and foreign literature at present.Therefore, the inspection technology of studying and set up such material evidence has important practical significance to solving criminal cases and court judgment.

The analysis of energy dispersion type X-ray fluorescence spectra is a kind of modern analytical technique, have that specimen preparation is simple, analytical element is wide, analysis speed is fast, analysis precision is high, do not damage advantages such as sample, its analysis principle is based on the photoelectric effect phenomenon: when a beam X-ray passes through material, a part is absorbed by the atom of material, be subjected to the atom of excitation of X-rays to send electronics and fluorescent X-ray again, according to the energy and the intensity of XRF that analyzed sample produces, can carry out the qualitative and quantitative analysis of element to sample.The spatial resolution of traditional energy dispersion type Xray fluorescence spectrometer belongs to mm ²～cm ²Scope can make the X ray of X ray light pipe emission produce the X-ray light spot of diameter from the hundreds of micron to tens of microns that total reflection obtains high order focusing by single or multiple kapillary optical systems; Therefore for the micro-beam X-ray fluorescence spectrometer of energy dispersion type, can obtain the space distribution of principal element and trace element by to the scanning of sample microcell.

Summary of the invention

The objective of the invention is to design a kind of highly sensitive, do not have destructive, can effectively check the method for being dyed black true, false bank note by dyestuff.

For achieving the above object, the present invention is a kind of to be dyed the black bank note method of inspection, comprises the steps: at least

(1) scanning:

Under micro-beam X-ray incident, analytic sample is carried out continuous-moving type scanning;

(2) obtain the element two-dimensional distribution of sample, i.e. the element mapping:

The energy and the intensity of the characteristic X-ray that each analyzing spot is excited are carried out check and analysis, form the sample element two-dimensional distribution that shows in ash value mode;

(3) compare of analysis:

First vegetarian noodles distribution characteristics to analytic sample and known bank note compares, and identifies the affiliated bank note kind of the sample true and false or judgement sample.

Further, described analytic sample is for being dyed black true bank note or false bank note.

Further, the serve as reasons organic dyestuff that contains hydrogen, carbon, nitrogen and oxygen or the organic dyestuff of the single heavy element of admixture of described analytic sample dyes black true bank note or false bank note.

Further, in order to be fit to the characteristics that bank note detects, the micro-beam X-ray fluorescence spectrometer parameter setting of described scanning step comprises: the X-ray tube voltage is that 35kV～40kV, X-ray tube current are that 500～1000 μ A, time constant are that 10 μ s～35 μ s, scanning element are 256 * 200 or 1024 * 800; The analyzing spot residence time is that 200 μ s～1000 μ s, sample chamber working pressure are 1.0 * 10 ⁵Pa～3.0 * 10 ^-2Pa.。

Further, the mode of described scanning is full element scanning, and the element sweep limit is Na～U, gathers the ultimate analysis scope characteristic X-ray that also analysis scan point excited in the scanning process, thereby obtains full element mapping.

Another scan mode is region of interest scanning, preestablishes the feature X spectral line of element of interest before the scanning, obtains setting the mapping of element of interest behind the end of scan.

Described compare of analysis is that comparison is analyzed in region of interest element spectral line analyst coverage, and described region of interest element spectral line analyst coverage comprises the K linear system characteristic X-ray of Mg, Al, Si, S, Cl, Ca, Fe, Ti element.

The present invention has following beneficial effect: because special paper material of bank note utilization and meticulous manufacturing process make, thereby have stability preferably, tangible migration can not take place being dyed the contained element in black back by organic dyestuff in bank note; And the bank note elements distribution feature has specificity, and different types of bank note unit vegetarian noodles distribution characteristics is variant.The present invention utilizes the micro-beam X-ray fluorescence spectral analysis to obtain being dyed first vegetarian noodles distribution of black bank note and identifies the sample true and false and judge its kind that this method is harmless, highly sensitive by first vegetarian noodles distribution characteristics, and the result is accurate, has a good application prospect.

Description of drawings

Fig. 1 is 1 dollar a bank note right side of face CaK distribution characteristics wherein for dying black space of a whole page volumes in 1999;

Fig. 2 is 100 dollars a bank note left side of face CaK distribution characteristics wherein for dying black space of a whole page volumes in 2006;

Fig. 3 dyes black true, false bank note for the identical quilt of outward appearance;

Fig. 4 is 100 yuan rmb paper currency frontal left CaK, ClK, FeK, a TiK distribution characteristics for dying black space of a whole page volumes in 2005;

Fig. 5 is 100 yuan Renminbi counterfeit money frontal left CaK, ClK, FeK, a TiK distribution characteristics for dying the higher space of a whole page volumes in 2005 of black fidelity;

Embodiment

Adopt the micro-beam X-ray fluorescence spectral analysis technique to be carried out first vegetarian noodles distributional analysis, obtain being dyed first vegetarian noodles distribution results of black bank note, identify the sample true and false and judge its kind according to first vegetarian noodles distribution characteristics to dying black bank note.

Dyed first vegetarian noodles distributional analysis result of black bank note: to dye black space of a whole page volumes in 1999 is 1 dollar bank note and to be dyed black space of a whole page volumes in 2006 be that 100 dollars bank note is example, two kinds of bank note all demonstrate the elements distribution feature identical with former bank note, and (the K linear system characteristic X-ray CaK with the Ca element is distributed as example, see Fig. 1, Fig. 2), show that special paper material and meticulous manufacturing process make bank note have stability preferably, though bank note is dyed black contained element tangible migration do not take place.In the actual swindle case, the suspect utilizes the characteristics of bank note stable components just, (heavy element is the element of atomic number Z＞30 with the organic dyestuff that contains light element (as hydrogen, carbon, nitrogen, oxygen etc.) component or the single heavy element of admixture, as I) organic dyestuff of component dyes bank note and it is restored after black again, thus the trust of gaining the victim by cheating.Light element in these dyestuffs or single heavy element composition do not influence the bank note element distribution analysis.

Being dyed the check of black true and false bank note (Fig. 3) identifies: the quilt that does not have an obvious difference with outward appearance dye true and false 2005 black space of a whole page volumes be 100 yuan Renminbi verify as example, with Ca, Cl, Fe, the K linear system characteristic X-ray CaK of Ti element, ClK, FeK, TiK distributes and makes comparisons, the element mapping (Fig. 4) that is dyed black space of a whole page volumes in 2005 and be 100 yuan bank note frontal left demonstrates ramage, national emblem, literal, numeral, safety line, information such as watermark, and the element that is dyed the higher counterfeit money same position of black fidelity distributes that (Fig. 5) show is numeral and figure information, and there were significant differences for both.

It is example that the present invention is dyed black bank note with the U.S. EDAX Eagle II micro-beam X-ray fluorescence spectrometer analysis that adopts the glass capillary focusing technology, it is equipped with Rh target X ray light pipe and single capillary Focused Optical system, X-ray light spot 300 μ m, detecting device Si (Li) 80mm2, the about 185eV of energy resolution (Mn K α, 10 μ s), Maximum Power Output 40W, maximum voltage 40kV.Utilize microbeam XRF nondestructive analysis laboratory sample.Under the micro-beam X-ray of incident, automatically controlling continuous the moving of sample by computer software scans sample, be continuous-moving type scanning, the characteristic X-ray photon that each analyzing spot excites enters energy detector, and by amplifier and multichannel analyzer processing formation spectrum, by continuous-moving type scanning, just obtain the two-dimentional distribution diagram of element of sample behind the end of scan.The element distribution results shows that in ash value mode the ash value is big more, and the representation element cellulose content is high more.

Its concrete steps are as follows:

One, scanning specifically comprises

1. will be dyed black bank note sample is fixed on the microbeam XRF sample stage with transparent adhesive tape;

2. start microbeam XRF vacuum system, make vacuum tightness reach the analysis requirement;

3. selection sweep limit: under 100 times of enlargement factors, focus on, take the sample close-up view in the Montage mode; Selecting determined rectangular area, four summits of sample is sweep limit;

4. definite region of interest (Region of Interest, ROI): the characteristic X-ray (as AlK, CaK, FeK, SK etc.) of selecting some common elements is interested analysis spectral line;

5. the setting running parameter is as shown in the table

Running parameter	Be provided with
		X-ray tube voltage (Voltage)	35kV?
X-ray tube current (Current)	1000μA?
		Time constant (Time Constant)	10μs?
Scanning element (Matrix)	256×200?
		The point residence time (Clock Time, clock time)	200μs?
Scan mode (Mode of Mapping)	Region of interest scanning (ROI Mapping) or full spectrum scanning (Spectral Mapping)

Region of interest scans, and preestablishes the feature X spectral line of element of interest before the scanning, obtains setting the distribution plan of element of interest behind the end of scan.

Two, obtain the element two-dimensional distribution of sample:

Under region of interest scanning (ROI Mapping) mode, what analysis obtained after finishing is the mapping that sets analysis spectral line interested (as AlK, CaK, FeK, SK etc.); And under full spectrum scanning (SpectralMapping) mode, not only obtain setting the mapping of analysis spectral line interested, and need not once more under the condition of scanning, can obtain the mapping of respective element spectral line by selecting other analysis spectral line.Therefore full spectrum scanning (Spectral Mapping) is preferred scan mode.

Three, comparative analysis:

Comparison is analyzed in region of interest element spectral line analyst coverage, described region of interest element spectral line analyst coverage comprises the K linear system characteristic X-ray of elements such as Mg, Al, Si, S, Cl, Ca, Fe, Ti, because above element exists well-regulated distribution usually in bank note, by the first vegetarian noodles distribution characteristics and the known bank note of analytic sample are made comparisons, identify its true and false and judge affiliated bank note kind.

Claims

1. a quilt dyes the black bank note method of inspection, it is characterized in that comprising the steps: at least

(1) scanning:

(2) obtain the element two-dimensional distribution of sample:

Carry out check and analysis at energy that is dyed the characteristic X-ray that in the black region each analyzing spot is excited and intensity, form the sample element two-dimensional distribution that shows in ash value mode;

(3) compare of analysis:

2. according to claim 1ly dyed the black bank note method of inspection, it is characterized in that: described analytic sample is for being dyed black true bank note or false bank note.

3. according to claim 2ly dyed the black bank note method of inspection, it is characterized in that: the serve as reasons organic dyestuff that contains hydrogen, carbon, nitrogen and oxygen element or the organic dyestuff of the single heavy element of admixture of described analytic sample dyes black true bank note or false bank note.

4. according to claim 1ly dyed the black bank note method of inspection, it is characterized in that: the micro-beam X-ray fluorescence spectrometer parameter setting of described scanning step comprises: the X-ray tube voltage is that 35kV～40kV, X-ray tube current are that 500～1000 μ A, time constant are that 10 μ s～35 μ s, scanning element are 256 * 200 or 1024 * 800; The analyzing spot residence time is that 200 μ s～1000 μ s, sample chamber working pressure are 1.0 * 10 ⁵Pa～3.0 * 10 ^-2Pa.

5. each is describedly dyed the black bank note method of inspection according to claim 1 to 4, it is characterized in that: the mode of described scanning is full element scanning, the element sweep limit is Na～U, gather the ultimate analysis scope characteristic X-ray that also analysis scan point excited in the scanning process, thereby obtain full element mapping.

6. each is describedly dyed the black bank note method of inspection according to claim 1 to 4, it is characterized in that: described scan mode is region of interest scanning, preestablish the feature X spectral line of element of interest before the scanning, obtain setting the mapping of element of interest behind the end of scan.

7. each is describedly dyed the black bank note method of inspection according to claim 1 to 4, it is characterized in that: described compare of analysis is that comparison is analyzed in region of interest element spectral line analyst coverage, and described region of interest element spectral line analyst coverage comprises the K linear system characteristic X-ray of Mg, Al, Si, S, Cl, Ca, Fe, Ti element.