RU2254354C1 - Coding composition and a method of recognizing components thereof - Google Patents

Abstract

FIELD: securities protection.

SUBSTANCE: invention relates to physicochemical protection of securities against falsifications. Coding composition contains one or several code-recognizing compounds, near IR region fluorescent agent, and IR-active compounds containing hydrogen-unbound or weakly bound X-H bonds (X = )-, N-, and ≡C-). Additionally included are IR-active compounds of general formula R₁-C≡C-R₂ (R₁ and R₂ are metal or halogen atoms). Method of invention resides in a single or multiple application(s) of one or several coding compositions onto object either avoiding spatial overlapping of compositions or in the form of compositions intersecting in different sequences of streaks, which sequences differ from each other in their code-recognizing components. Recognition of mutually masked code-recognizing and IR-active components is achieved either by way of varying wavelength in excitation spectra or varying intensity and shape of spectra in near IR fluorescence region. Sequence of applied streaks is determined from conformity of code-recognition spectra in higher monomolecular layer (or several monolayers) of composition in a streak intersection point to spectra of individual streaks.

EFFECT: increased information capacity of protection system due to increased diversity of differentiated components.

3 cl, 7 dwg, 6 ex

Description

The invention relates to the field of physical and chemical protection against counterfeiting of securities (banknotes, checks, bills, warehouse certificates, etc.), printed matter (passports, licenses, certificates, tickets, plastic cards, etc.), valuable documents manuscripts, works of art, packages of goods, jewelry, etc. As protection elements, special images, tags, tracers, or special coding systems are usually used ("tags" - "labels" from the English word Tag - a label or passport of objects).

There are three levels of analysis or verification of security features:

I. Non-destructive express diagnostics in “field” conditions by an unskilled user visually and / or using inexpensive detection devices;

II. analysis (diagnostics, identification) with the possible use of a complex of partially destructive methods in laboratory conditions using standard equipment (spectrometers, etc.) and with qualified personnel;

III. analysis (diagnostics, identification) in the laboratories of manufacturing developers using either special equipment or standard equipment using specific “know-how.” Competition of security system developers with clandestine level II laboratories requires the development of such high-tech technologies that prevent the production of fakes or imitations of elements protection indistinguishable from scripts at level I.

Typical protection elements for visual (or using a magnifying glass) definitions are, for example, holographic images, colored micro-fibers or colored multilayer microparticles - microtags. The latter are interesting in that, due to variation in the color of the layer and their sequence, they can encode information on a significant number of objects, i.e. are an encoding composition. Protection elements based on effects of a physicochemical nature include photo- and thermochromic paints, optically variable multilayer coatings. Numerous traditional security elements based on color UV luminescence fall into the same category. A relative innovation among them is the introduction of luminescent compositions in the form of paper impregnation or a laminating coating in order to prevent photocopying of a document by creating interference (illumination).

With obvious conveniences, the drawbacks of visual authentication systems are the need for continuous retraining of users, as well as the unreliability of the quantitative comparison of features and its reproducibility. There is an increasing need for the production of machine-readable security systems for automating recognition processes, for example, for sorters and banknote counters, securities counters and other purposes.

Optical machine-readable security systems are known. Patent [Stenzel G., Lehle E. Paper secured against forgery and device for checking the authenticity of such papers. US Patent No. 4146792, Mar. 27 1979] disclosed is an optical paper protection system based on the introduction of labels that fluoresce in the visible, ultraviolet and infrared ranges, and a reader device containing a source, filters and detectors. A more advanced method of protection is described in the patent [Schvoerer M., Ney C. Procede de marquage d'objets par microcristaux a effet de memoire et marqueurs pour sa mise en oeuvre. European Patent No. 0282428 B1, 1992], where complicated effects are used, for example, thermoluminescence, when the appearance and disappearance of luminescence is observed in the process of increasing the temperature of the sample. Magnetospin effects known from the literature on photoluminescence can be attributed to such complications [M.M. Tribel, E.L. Frankevich. The study of magnetic and spin effects in molecular crystals and polymers. RFBR Newsletter, vol. 3, No. 3, p. 159, 1995], when changes in the luminescence intensity of labels are observed with a change in the magnetic field. Such a system is also attractive for creating coding compositions differing in the relative magnitude of effects in different spectral regions of the visible-near-IR range, but their disadvantage due to the low specificity of the spectra is the unreliability of differentiation of different compositions in the presence of background noise distorting the relative magnitude of the effect.

The above systems are based on non-destructive methods of electron spectroscopy (reflection, fluorescence), which are characterized by high sensitivity and high intrinsic half-width of the bands, which allows the use of low-cost low-resolution detection devices. However, unlike, for example, vibrational spectroscopy methods, which are a classic tool for chemical identification of compounds, a common drawback of electron spectroscopy methods is their low selectivity and specificity, which makes it possible to fabricate fakes or simulate protection elements indistinguishable for level I detectors.

Analogs

Methods of vibrational IR and Raman spectroscopy using detection devices of higher spectral resolution make it possible to create more advanced protection systems due to the presence in their spectra of a significant number of narrow specific bands having the character of fingerprints of compounds. However, IR absorption spectroscopy requires sample preparation and sample destruction. To implement non-destructive reflection methods, special lenses for IR microscopes have recently been developed [A.Kh. Kuptsov. Device for measuring diffuse reflection spectra. USSR copyright certificate, No. 1637520, November 22, 1990, DWSting, ATR objective and method for sample analyzing using an ATR crystal, USA Patent No. 5093580, March 3, 1992], however, the cost of such devices is high and, for a number of technical reasons, they cannot be used as level I detection devices. The “Achilles heel” of the non-destructive method of non-resonant Raman spectroscopy in the visible range due to the weakness of this effect (~ 10 ^-8 ) is impurity fluorescence (quantum yield ~ 10 ^-3 ÷ 10 ^-5 ), which covers the Raman spectra of most objects used in everyday life. The development of semiconductor technology has allowed the creation of near-infrared laser sources and detectors, where the background, as it turned out, decreases more significantly than the Raman intensity. Non-destructive systematic study of found materials by Fourier Raman spectroscopy in the near infrared showed that more than 80% of the samples are suitable for analysis (for example, polymers whose Raman spectra are most often overlapped by fluorescence [Agbenyega JK, Ellis G., Hendra PJ Raman spectra of polymers. J. Wiley & Sons, 1997, 120 pp, Kuptsov AH, Zhizhin GN Handbook of fourier transform raman and infrared spectra of polymers. Elsevier Science, Amsterdam, Netherlands, 1998, 570 pp, A. Kuptsov, Zhizhin G .N. Fourier-KR and Fourier-IR spectra of polymers. M: FIZMATLIT, 2001, 657 pp.]). Note that in order to increase the noise immunity of traditional electronic spectral protection systems, a patent has recently been proposed [Albert B., Closs F., Kipper J., Kurtz W, Beck KH, Griebel R. Use of a liquid containing IR dyes as printing ink. USA Patent No. 5282894, 1994], disclosing a composition with dyes of the near infrared range. Serial spectrometers have appeared that are suitable for analysis not only at level II, but also relatively inexpensive mobile portable devices of the red-near infrared range (from 630 to 1700 nm) with semiconductor lasers and CCD arrays or arrays for level I. Let’s clarify that This category of devices includes low-resolution spectral devices with a resolution of less than 0.5 × 10 ³ (or a resolution of more than 15-20 cm ^-1 ), while high-resolution devices are assigned under the condition> 5 × 10 ⁴ (or with a resolution of less than 0 , 1 cm ^-1 ), in the interval - medium him permission. Standard serial devices of the last two categories belong to level II.

The most attractive for creating protection systems are resonance methods of Raman spectroscopy or using the so-called Raman active (having several orders of magnitude more intense Raman) materials. So in the patent [Macpherson I.A., Fraser I.F., White P.C., Munro C.H., Smith W.E. Pigment compositions. USA Patent No. 5718754, 1998] a system based on a composition of various azo, azo-methine and sex and cyclic chromophores readable by the visible resonance Raman (RRC) method is proposed. It is known that the molecules of many substances adsorbed on the surfaces of certain metals (silver, gold, copper, and some others) or their hydrosols exhibit Surface-Strengthened Raman bands (SCCR or SERS), which are especially intense in the case of resonant excitation of the adsorbate (SCCR or SERRS). This phenomenon was used in protective elements based on compositions containing OCRC-active aggregates of compounds on metal sols [Macpherson I.A., Fraser I.F., Wilson S.K., White P.C., Munro C.H., Smith W.E. Pigment compositions. USA Patent No. 5853464. 1998]. Although well-versed in the UPKR (UPKR) technology, a huge number of problems are known related to the reproducibility of this effect and its reliability. Recently in a patent [Kazmaier P.M .. Buncel E.S., Herbert F. Method for document marking and recognition. USA Patent No. 5935755, 1999] proposed the use of combinations of a significant number of conditionally RS-active nzcomolecular compounds, groups, chromophores, etc. as tags. The distinguished convention of the Raman active compounds included in the long list of the patent is due to the fact that in reality most of these compounds have a rather low degree of superiority in scattering cross sections compared to conventional compounds, in the best case corresponding to the intensity of the Raman dyes.

Advances in the development of photoconductive optically nonlinear materials for the modern needs of electronics have led to the emergence of polymeric materials with extremely intense Raman scattering. This primarily applies to polymers of the class of polydiacetylenes - [= CR-С≡С-CR '=] _n (PDA), especially in samples forming the so-called "Pack" of polymer chains and having a crystalline structure. The synthesis of RC-active RC≡C-C≡CR 'monomers from CR is described in [Yee L, Carbazolyl diacetylenic compounds. USA Patent No. 4125534, Nov. 11, 1978]. The intensity of the Raman bands of the skeleton of polymer chains is two orders of magnitude higher than the intensity of the resonant Raman bands on the side chains and groups of these polymers, as well as the characteristic intensities of the Raman bands of the dyes.

An analogue is the patent [Bralchley R "Nugeni NO, Ellis LS Ink Composition and Components Thereof. USA Patent No. 5324567, Jun. 28, 1994], which describes the use of some crystalline PDAs as a label (and not coding compositions) for protective printing inks. In this case, it was proposed to recognize PDA by recording Raman spectra in the region of triple bond bands, where the most intense PDA band lies, in comparison with the Raman spectrum of a reference sample under the same conditions.

A similar example of extremely high Raman active materials of another class can be low-defective trans-polyenes, for example, polyacetylene [-CH = CH-] _n (PA), the synthesis of which is described in [Kobryansky V.M. High molecular weight compounds, ser. B, 1994, 36, No. 5, pp. 881-894]. The properties of the low defective trans-nano-PA composition stabilized in a transparent polyvinyl butyral polymer matrix are described in [Kobryansky V.M. Raman scattering of a highly ordered trans-nano-polyacetylene composition. Papers of Physical Chemistry, vol. 362, 1998, pp. 295-298, VMKobryanskii, AHKuptsov, DYParaschuk, ANShchegolikhin, NNMelnik. Raman spectroscopy in nanopolyacetylene. In: Raman spectroscopy and light scattering technologies in material sciences, Proc. SPEE No. 4098, 2000. (4098-29)] (the quantum yield above the matrix material is 4-5 orders of magnitude, ie, about 10 ^-3 ).

A method of protection against fakes based on the introduction of coding compositions using highly Raman active materials from the classes of polydiacetylenes (PDA), diacetylene monomers (MDA), alkylene polyenes or polyacetylenes), diamond films and their verification by near-infrared Raman spectroscopy ( see Fig. 1) was published by us in [Kuptsov A.Kh. Methods of vibrational spectroscopy in the problems of identification of materials and technologies. Abstract. diss. student Step.Doct. Phys.-Math. Sciences, M., 2000]. Later, a U.S. patent application appeared [A.N.Schegolikhin, O.L. Lazareva, V.P. Melnikov, V.Y. Ozeretski, L.D.Small. Raman-active taggants and their recognition. Pub. No: US2002 / 0025490 A1, 2002], which is adopted as a prototype.

Prototype.

The coding composition in the form of liquid or solid compositions based on one or more Raman active compounds from a number of monomers and polymers of acetylenes and diacetylenes, including thermochromic, linear polyines, trans-polyacetylenes, polyenes, squarans, cyanoacrylates, polyimines, polyazines, poly ( ethynylene) arylene, poly (ethynylene) heteroarylenes, fullerenes and tubulenes, and fluorescently active phosphors in up-conversion, as well as a method of applying a coding composition and recognition of its components, including applying (introducing) it to object in the form of liquid or solid compositions and method of detection nonresonant Raman spectroscopy in the near infrared range.

The disadvantages of the prototype.

1). A common feature of the vibrational spectra of most compounds is the presence of the most intense bands in the range from 400 to 3600 cm ^-1 and an almost empty region in the middle of the range from 1800 to 2800 cm ^-1 (the so-called triple bond region). This region makes up a third of the measurement region, and its “void” is a disadvantage in terms of the density of information distribution along the axis of vibration frequencies. Although the characteristic vibrational bands of acetylene groups lying in this range are the most intense in the spectra of Raman active components and do not overlap with the bands of substrates that are absent in this range, on the other hand, they easily reveal the chemical nature of the coding compositions and contribute to their falsification.

2). The prototype asserts the position that non-resonant conditions for registration of Raman scattering are more preferable in comparison with traditional counterparts - resonant Raman scattering methods - from the point of view of quantitative analysis in solving identification problems. This provision is fair and only partly appropriate. Firstly, the element of inappropriateness is due to the fact that both in patents of analogues and in practice, the initial task at level I is express authentication (or identifying fakes) - a diagnostic and not an identification task. A qualitative analysis may be sufficient here. And rather the opposite - the need to use at this stage non-destructive analyzes of quantitative methods for the differentiation of coding compositions is a disadvantage, not an advantage. Identification, in practice - forensic identification for the purpose of identification and proof, takes place at level II in forensic or forensic laboratories (or in clandestine laboratories for the manufacture of fakes or imitations), where, along with non-destructive, informative and successful are used methods with partial destruction of samples. Secondly, the secondary absorption of spontaneous Raman quanta is less than that of Raman quanta, but nevertheless takes place on impurities or operational impurities. Thirdly, differences in the integrated fluorescence background intensity of the measured samples affect the temperature of the cooled near-infrared semiconductor detectors, respectively, their spectral response and, therefore, the accuracy of quantitative measurements of spontaneous Raman scattering. Therefore, in real conditions, spontaneous Raman scattering, as well as Raman scattering, has its limitations as a quantitative method. Thus, the objectives of the invention, namely, the expansion of the variety of coding compositions and the possibility of their differentiation for the purpose of diagnosis at level I, would be more consistent not with the desire for conditions when there is no absorption in the region of the frequency of excitation of Raman scattering (which, when operating in real conditions almost impossible), and the creation of a system on the basis of a qualitative or semi-quantitative at the level of the ratio of intensities of the neighboring differentiation bands.

3). To solve the identification problems (referred to in the prototype application), time-unstable components are unsuitable, which include, for example, diacetylene monomers (including irreversibly thermochromic). Over time, they in the process of solid phase polymerization go into another form declared as separate components.

4). The application indicates that the Raman active components (12 classes are indicated) and, accordingly, compositions based on them are characterized by the presence of bands in the range of 2300-1900 cm ^-1 and can produce contributions of the individual components that are distinguishable in the total spectra, with up to six components simultaneously, which was shown by a concrete example. Moreover, it is proposed to use up to 9 Raman actives and one luminescent compound from the above two varieties of the so-called "Phosphorus up-conversion." We note that only 9 classes of compounds of the indicated 12 contain triple bonds and indeed contribute in this range. In addition, far from any combination of even 6 components out of 9 possible classes of compounds gives spectrally distinct patterns. In fact, this interval of 400 cm ^-1 is not uniformly filled and several clusters stand out in it. For example, the lowest-frequency bands are characterized by organoelement acetylene groups (Me-C≡CR) with maxima of about 1950-1920 cm ^-1 , and the highest-frequency bands are the maxima of the bands of diacetylene monomers of the general formula (RC≡C-C≡CR '), which lie in a narrow area of 2270-2255 cm ^-1 . The polymers of the latter formulas (= RC-C≡C-CR '= R'C≡C-CR =) or (= RC-C≡C-CR' = RC≡C-CR '=) give stripes in the region 2120-2080 cm ^-1 The bands of two components are distinguishable if their maxima are located at a distance greater than the half-width of the component bands, and the characteristic half-width averages about 30 cm ^-1 . Although the half-width of one of the bands of the overtone of polyacetylene at 2150 cm ^-1 is about 80 cm ^-1 For this reason, representatives of one class in the claimed frequency range of 2300-1900 cm ^{-1 are} difficult to distinguish from each other (and in the area of “fingerprints” give interference to the substrate strip and other components of the composition). Note that with the aforementioned half-widths of the bands, it is possible to reduce the spectral resolution from 4-7 cm ^-1 down to 15-20 cm ^-1 without much damage to the separation of components. Thus, the number of reliably distinguishable combinations in the prototype is quite limited, and the possibility of increasing the information capacity the system depends little on the spectral resolution of the instruments.

5). Among the structures indicated by the general formulas with acetylene groups and substitutions around them, the simplest structure of the form R ₁ -C≡C-R _{2 is} missing, where R _1,2 is a metal or halogen. And the double value of precisely these types of structure lies, firstly, in their lowest non-overlapping frequency range relative to other acetylene-containing structures, including Me-С≡CR type, where R is an organic radical, but not a metal or halogen, but secondly, due to the symmetry of the structure with a multiple bond and heavy atoms, it is especially active in Raman scattering. Many experimental confirmations of the last rule can be found in the book [A. Kuptsov, G. Zhizhin. Fourier-Raman and Fourier-IR spectra of polymers. M .: FIZMATLIT, 2001, 657 pp.].

The technical objectives of the present invention are:

1. a significant increase in the information capacity of the protection system (increasing the variety of differentiable components) without a noticeable increase in the cost of detecting devices of level I and the cost of manufacturing compositions;

2. complication of decryption of protection elements when using standard equipment of level II;

3. A new method of encoding and reading information by a level I detection device based on determining the sequence of applying intersecting strokes;

4. A new method of non-destructive diagnostics of artificial refinement and falsification of precious stones in jewelry without removing them from the frames using a level I detection device.

The technical result is achieved by the fact that

1. In the coding composition containing one or more Raman active compounds from a number of squarans, cyanoacrylates, monomers and polymers of acetylenes and diacetylenes, including thermochromic, linear polyines, polyimines, polyazines, poly (ethylene) arylene, poly (ethynylene) heteroarylenes , trans-polyacetylenes, polyenes, fullerenes, tubulenes and fluorescently active phosphors at up-conversion, add near-infrared fluorophores, including those giving rise to the RKR spectrum, and IR-active compounds containing hydrogen-unbound or weakly of X-linked -bond H, X = O-, N-, ≡S- giving an empty area Raman spectra from 1800 to 2800 cm ^-1 negativnoobraschennye secondary absorption band near infrared overtones fluorescence X-H stretching vibrations are mutually masked with bands of KP-active compounds, while compounds of the form R ₁ -C≡CR ₂ , where R _1,2 is a metal or halogen, are additionally classified as a number of KP-active compounds.

The proposed coding composition is illustrated as follows.

Up-conversion fluorescence-active phosphors or, as they are often called in Russian literature, anti-Stokes phosphors - oxides or halides of activated rare-earth elements can be respectively represented by general formulas of the form

R _{2 (1-x)} D _2x O _3-z S _z or R _(1-x) D _x Hal,

where R is the rare earth elements like yttrium, cerium, lanthanum, erbium, gadolinium, D is an element from the group of neodymium, erbium, yttrium, cerium, lutetium, ytterbium, holmium, thulium, samarium, europium, Hal is halogen like chlorine, fluorine, bromine, iodine, x is a number less than 1, z is 0 or 1.

Near-infrared fluorophores - organic, metal-organic or inorganic dyes or pigments that fluoresce in the near-infrared range. Typical examples of organic and metal-organic compounds are free or metal-containing phthalocyanines, naphthalocyanines, acid blue-black dyes, nickel-dithiene complexes, etc. Inorganic - iron oxide pigments, chromium dioxide, lead chromate, etc.

In compounds of the form R ₁ -C≡CR ₂ , where R _1,2 is a metal or halogen, metals include, for example, sodium, potassium, lithium, and halogens include iodine, bromine, chlorine, fluorine.

2. A method for recognizing the components of the coding composition, including applying to the object and / or embedding in its volume and recognition by near-infrared Raman spectroscopy, in which the coding composition is applied according to claim 1 without overlapping its strokes on the object, or in in the form of strokes intersecting in different sequences, for which two or more compositions are used in intersecting strokes, differing only in RC (RRC) - active components, and recognition in each coding composition by 1, by the method of Raman spectroscopy in the near infrared range of mutually masked Raman and IR active components, they are carried out either by changing the wavelength of the excitation of the spectra in the range 970-1200 nm, or by varying the intensity and shape of the spectra of near infrared fluorescence of the components due to their thermoluminescence properties, magneto-optical properties or magnetospin effects, photo- and thermochromism, pH, piezo and solvatochromism, Raman enhancement effects (CCR) and fluorescence suppression when colloidal silver is applied to the surface of the composition Or gold or copper, and determination of the sequence encoding streaking compositions produced based on the correspondence UPKR spectra upper monomolecular layer, or a few monolayers compositions primes intersection point UPKR spectra of individual strokes.

The introduction of the coding composition into an object can be carried out either in a liquid or pasty state of the latter or in the process of its manufacture until the transition to the state of curing.

The coding composition according to claim 1 is applied on the brink of a gemstone, including in jewelry, in the process of non-destructive and precluding sample preparation in the “field conditions” for diagnosing falsification of natural stones with synthetic ones according to the IR absorption bands of overtones of OH stretching vibrations.

The technical result is also achieved by the fact that the monomers of diacetylenes, eventually turning into a polymeric form, are used as indicators of the time of application of the composition, and not as identifying components, as suggested in the prototype. So, for example, if they are present in the composition of pastes (inks) for pens, it becomes possible to confirm or deny the date of signing of documents by the degree of conversion to polymer.

The examples below confirm the main points formulated in the technical solution.

Example 1

It shows that in the empty region of the Raman scattering very intense bands can be observed due to the secondary absorption of the overtones of X – H stretching vibrations, which exceed the intensity of the Raman bands of the same compounds. When RS is excited on the 1064 nm line of an Nd: YAG laser in the near infrared range of kaolinite samples, along with Raman and fluorescence spectra, secondary absorption bands of impurity fluorescence are observed (after primary, causing fluorescence), as can be seen from figure 2. In the IR spectra of the middle and near range of aluminum kaolinite-hydrosilicate (on the left in FIG. 2), very intense stretching bands are observed that are not hydrogen bonded to OH groups of about 3621, 3653, 3670, 3695 cm ^-1 , and their overtones are about 7066 , 7112, 7140, 7170 cm ^-1 . All spectra were obtained on a Bruker Fourier spectrometer (Germany), model IFS 66 with the Raman module FRA106. The overtone bands reproduce the characteristic outline of the fundamental tones and are quite intense. In Fig. 2, to the right, the group of bands with downward maxima of about 2328, 2282, 2254, 2224 cm ^-1 corresponds to the difference in the wave number of the exciting Nd: YAG-na3epa, 9394 cm ^-1 , and the wave number of the bands about 7066, 7112, 7140, 7170 cm ^-1 and reproduces this contour, which confirms their belonging to the bands of secondary absorption of fluorescence by IR overtones. Moreover, their intensity far exceeds the intensities of all Raman bands of kaolinite. The intensities of overtones are usually several orders of magnitude weaker than the fundamental tones, however, the very IR-active stretching vibrations of X-H bonds are characterized by amplitude and strongly anharmonic proton motions and have the most intense overtones. In addition, fluorescence excited in a solid sample upon diffuse scattering in a volume leads to an increase in the degree of absorption.

Example 2

A demonstration that the relative intensity of the overtone bands in the recorded spectra is related to the fluorescence intensity and varies proportionally with it, and not the Raman scattering, is shown in FIG. 3. The spectra were obtained upon excitation on the 1064 nm line of an Nd: YAG Fourier spectrometer laser IFS66 with FRA106 module. Sample No. 1 is an industrial sample of semi-finished talc (magnesium hydrosilicate) in surfactant micelles used in paints and varnishes. Sample No. 2: a mixture of sample No. 1 - 99 hours. and industrial semi-finished iron oxide pigment - 1 part by hour, prepared using a ball vibratory mill. The starting components were obtained at a paint and varnish enterprise in Yaroslavl. The addition of fluorophore increases the intensity of fluorescence in the near infrared range (upper spectrum in figure 3). The downward-facing bands correspond to the absorption of overtones of OH stretching vibrations of talc (stronger about 2212 and less - about 2244 cm ^{-1 are} characteristic in that they are observed in the IR spectrum of talc - more intense about 3676 and less - about 3692 cm ^-1 ) . In the spectrum of sample No. 1, the relative intensity of the overtones is weaker than the intensities of the Raman bands of talc, while in the spectrum of sample No. 2 they are much higher than the intensities of Raman scattering and increase in proportion to the fluorescence intensity.

Example 3

A demonstration of the mutual compensation and masking in the near infrared range of the bands of Raman active components and IR active components is shown in Fig. 4. A sample of industrial semi-finished kaolinite in surfactant micelles for paints and varnishes was mixed using a vibrating mill with diacetylene monomer (1,6-bis ((4-carbonyl) -phenoxy) hexa-2,4-diine) - (ethylenediamine) in a ratio of 3: 5, after which the latter is polymerized by solid-state reaction in PDA at a temperature of 215 ° C for 6 hours. The spectrum was obtained upon excitation on the 1064 nm line using an IFS66 Fourier spectrometer with a FRA106 module. The imposition of bands with maxima facing up (corresponding to MD Raman spectra of about 2260 cm ^-1 and PDA Raman of about 2115 cm ^-1 ) and down (IR absorption of overtones ν _OH kaolinite), as can be seen from figure 4 in comparison with Fig. 2, complicates the decoding of the structural-group composition when using standard equipment. Indeed, the Raman maximum of about 2115 cm ^-1 looks at least between the IR bands facing down, and the bands of about 2260 cm ^{-1 are} generally not noticeable between the IR absorption bands. Note that masking of narrow fluorescence bands of phosphors at up-conversion of about 2700-3100 cm ^-1 can be achieved due to components absorbing in the range of about 200 cm ^-1 slightly higher than 3150 cm ^{-1 of the} IR spectrum (the overtone frequency is usually somewhat lower than twice pitch value).

Example 4

A variation in the intensity of the fluorescent background (a significant reduction in the contribution) in order to decipher the RKR-active components of the coding composition is shown in Fig. 5 using an industrial organic blue-black acid dye obtained from NIIOPIK as an example. The dye, due to long-wavelength absorption, gives near-infrared fluorescence, as well as weak bands of the RKR spectrum (upper spectrum in Fig. 5). The sample was a 20% aqueous dye solution (ink) deposited on a sheet of white paper (as well as embedded in the volume of a sheet of paper). Raman spectra were recorded after the ink dried. The relative weakening of its fluorescence upon adsorption on the surface of colloidal silver and at the same time an increase in the contribution of the RKR dye is achieved due to the SARC effect (lower spectrum), by adding successively 2 microdrops of approximately 5 μl of commercially available prepared aqueous solutions of polylysine at a concentration of 0.01% and colloidal silver at a concentration of 0.15% directly to the area with dried ink. When using the same concentrations of colloids with other metals - gold, copper - a slightly lower magnification of Raman spectra and, accordingly, relative background attenuation are achieved. The Raman spectra on the surfaces of colloidal particles of various metals do not have the bands of the colloids themselves and are represented only by enhanced dye bands; therefore, the differences are associated only with the total intensity of all the dye bands as a whole and the contribution of the fluorescence background (for this reason, the Raman spectra of other metals are not shown). However, gold colloids are more stable over time, are stored for a long time and do not require freshly prepared solutions. The spectra were recorded upon excitation on the 685 nm line of a diode laser using a FORAM685-2 Raman spectrometer from FOSTER-and-FREEMAN (England). The microdroplet application kit and the solutions themselves were obtained from FOSTER-and-FREEMAN. It should be noted that the addition of fresh solutions of colloidal silver ensures the presence of an intense RCC effect, in contrast to a similar system immediately introduced into the composition, as proposed in the patent [Macpherson I.A., Fraser I.F., Wilson S.K., White P.C., Munro C.H., Smith W.E. Pigment compositions. USA Patent No. 5853464. 1998].

Example 5

When applying two or more compositions, additional hidden coding is possible, based on the method of determining the sequence of applying intersecting strokes. For example, intersecting guilloche patterns of different colors are often used as protection against copying securities. The sequence of applying signatures and stamps in documents, text supplements also raise questions about the sequence of applying intersecting strokes. Twenty years ago in the journal of the American Academy of Forensic Sciences [Taylor L.R. Intersecting Lines as a Means of Fraud Detection. // Journal of Forensic Sciences. - 1984, v.29, n.1, p.92-98] described methods for establishing their sequence. Since then, various modifications and approaches have appeared, but the sequence of applying two strokes of the same color and close composition (for example, two pastes of black color or both blue of the same shades) is still a problem. We have developed an approach based on the analysis and comparison of the spectra of individual strokes and their intersection using the Raman spectroscopy method, which is especially effective when using the UPCR technology (see Fig. 6). This technology allows to obtain high-quality spectra of the upper monolayers of writing material due to their amplification applied in a certain way to the analyzed point by colloidal silver. The use of this method of solving the problem in the literature (including patent) is not described. Meanwhile, using two pens with ink (pastes) of the same composition, one of which contains a KP-active component (or both with different ones), and UPKR technology (UPRKR), you can create protected documents with binary encoding of information based on a sequence of intersecting strokes. This example demonstrates the possibility of determining the sequence of the intersection of the strokes of two blue compositions with different OCRC-active fluorophores of the near IR range in weight concentrations of about 15% in the form of standard pastes for ballpoint pens based on phenol-formaldehyde resins. In the first composition, a standard paste for ballpoint pens of domestic production (NIOPIK), the UPRKR-active component, a phthalocyanine dye, was used. In the second - paste of Italian production for ballpoint pens Corvina - dye type fat-soluble violet - Methyl Violet. Figure 6 shows the intersection of the strokes of the two given compositions (their CRC spectra are b and c, respectively, in Fig. 6) in two different sequences of their deposition (the CRC spectra at the centers of the zone of intersection of the strokes a and d), and the second stroke is applied after completely dry first. Correspondence of the Raman spectra of the spectra of the upper monolayer of the composition at the point of intersection of strokes to the spectra of individual strokes shows which composition was applied later. It is impossible to achieve an error-free reading of the sequence of intersections in such a case by any other method traditionally used in forensic laboratories.

Advantages of using additional types of fluorescent and IR-active components simultaneously with Raman-active components of the coding composition:

- With standard excitation at 1064 nm (or non-standard in the range 970 - 1205 nm), the bands of additional components fall into the above-mentioned empty region of Raman spectra, which, firstly, can significantly increase the information capacity of Raman spectra by bands of IR-active vibrations forbidden or weak in Raman scattering, and secondly, overlap and mutually mask the bands of the components of the coding composition based on acetylene groups, bands of triple bonds and other vibrational bands of this range.

- Characteristic, diverse in form, narrow and intense secondary absorption bands of overtones of hydrogen-unbound valence X-H vibrations, in particular O-H vibrations, can be used as components of the coding composition that are not observed during traditional excitation in the visible range. The X-H-groups free of hydrogen bonds (X = O-, N-, ≡С-, С-, S-) are analytically very convenient, since they are narrow, intense, do not overlap and lie on the highest-frequency edge of the IR- spectra (they lie in the range from 2500 to 3750 cm ^-1 , but the first three, which lie in the range of 3300-3750 cm ^-1 , are most convenient, see the ν _OH bands in Fig. 2). The bands of the first three types of bonds are not found in the vibrational spectra of typical substrates (with the exception of those containing fillers such as kaolinite and talc) like paper, polymers, metals, since X-H bonds are present in them in a hydrogen-bound form, which leads to a significant ( depending on the strength of the H-bond by hundreds or even up to a thousand cm ^-1 ) a decrease in the frequency of their vibrations and broadening.

- The distances between the maxima of the overtone bands and their half-widths are slightly higher than those of the fundamental tones, which facilitates the spectral requirements for the equipment in terms of resolution. To demonstrate the range of OH stretching vibrations in figure 2 below, along with kaolinite bands, are given the bands of the gibbsite spectrum - aluminum hydroxide, which, by the way, are the most intense in the spectrum of this mineral. The huge variety of bands of only OH groups only in the IR spectra of minerals can be seen from the book [Plyusnina I.I. Infrared spectra of minerals. From Moscow State University, 1977].

Ways to reduce the cost of protection system components as a whole based on the benefits achieved:

1. The coding composition. As its components, only the most Raman active components listed in the prototype are used, and at the same time, up to 9 such components, each of which has a rather high cost, are not included in the composition, and are limited to a maximum of 6 different classes with well-separated maxima . The set of Raman active components is expanded by relatively cheaper IR dyes in one of the following series: phthalocyanines, naphthalocyanines, nickel-dithiolene complexes, amine compounds of aromatic amines, methine and other dyes, as well as relatively inexpensive IR active compounds with X-H -connections.

2. Detecting devices can be cheapened by lowering the requirements, for example, in resolving power, since the standard resolution of 4-7 cm ^-1 (as mentioned in the prototype) is not required to differentiate the heterogeneous components of the encoding composition, but 20 cm ^{-1 is} enough that with the same recording range per matrix or ruler allows you to more than three times reduce the number of detector pixels and significantly win in price (detectors are the most expensive parts of devices). The spectral range of the detecting device compared to the standard range of registration of Raman spectra from 100 to 3500 cm ^-1 can be narrowed to the limits from 1300 to 3100 cm ^-1 . In Fourier spectrometers, the stroke length of a movable mirror can be reduced three times. Moreover, the addition of a table with controlled heating or a solenoid with a magnetic field will not lead to a noticeable rise in the cost of the detection system.

3. Means of application to the substrate. In addition to the traditional use of compositions as part of printing inks, which is limited by the capabilities of the equipment or requires special devices for applying to complex surfaces (for example, to protect works of art, etc.), as well as performing this procedure by the consumer himself without using printing equipment, it is proposed to introduce coding compositions and in the composition of pastes or inks for pens.

Thus, the advantages of the proposed technical solution can significantly reduce the cost of the coding, protection and authentication of objects as a whole.

Example 6

A portable Raman spectrometer and a technique for recognizing components of coding compositions in the proposed method can also have additional applications, namely, for diagnosing falsification of a number of precious stones, for example emeralds. It is known that one of the ways to differentiate natural gemstones from synthetic fluxes is to analyze for the presence (or accordingly absence) in the IR spectra of bands of stretching OH vibrations. To obtain IR spectra of good quality stone in jewelry, it needs to be plane-parallel cut and removed from the frame. The latter, if undesirable, it is possible, however, to change the faceting of the stone to the convenience of the method is not possible. In addition, an expert gemologist is not always at hand with a rather expensive and bulky IR spectrometer. However, upon excitation of the Raman spectra in the near-IR range on the 1064 nm line of the Bruker IFS66 Nd: YAG Fourier spectrometer (Germany) with the FRA106 module simultaneously with the Raman bands in the empty region, the above-mentioned secondary absorption bands of the overtones of the ν _OH bands are observed the presence of which are different from natural synthetic flux stones, in this case emeralds (Fig.7).

The example shows how, by pressing a composition containing an IR dye to an adjacent or opposite face of a stone, where a laser beam hits from the inside, it is possible to diagnose the presence or absence of signs of the genetic type of stone - natural or synthetic flux. Moreover, the above bands can be detected by an inexpensive portable Raman spectrometer.

Claims (3)

1. An encoding composition containing one or more Raman active compounds from a number of monomers and polymers of acetylenes and diacetylenes, including thermochromic, linear polyines, trans-polyacetylenes, polyenes, squarans, cyanoacrylates, polyimines, polyazines, poly (ethynylene) arylenes , poly (ethynylene) heteroarylenes, fullerenes and tubulenes, and fluorescently active phosphors on upconversion, characterized in that they add near-infrared fluorophores, including those giving RKP bands, and IR-active compounds containing hydrogen single-bonded or weakly bonded Х-Н bonds, where Х = О-, N-, ≡С-, giving in the empty region of the Raman spectra from 1800 to 2800 cm ^-1 negatively reversed secondary absorption bands of near infrared fluorescence by X- overtones H valence vibrations mutually masked with bands of Raman active compounds, while compounds of the form R ₁ —C≡CR ₂ , where R _1,2 is a metal or halogen, are additionally classified as a series of Raman active compounds. 2. A method for recognizing the components of the coding composition, including applying to the object and / or embedding in its volume and recognition by near-infrared Raman spectroscopy, in which the coding composition is applied according to claim 1 without overlapping its strokes on the object, or in in the form of strokes intersecting in different sequences, for which two or more compositions are used in intersecting strokes, differing only in RC (RRC) -active components, while recognition in each coding composition by .1 the method of near-infrared Raman spectroscopy of mutually masked Raman and IR active components is carried out either by changing the wavelength of the excitation spectra in the range 970-1200 nm, or by varying the intensity and shape of the near-infrared spectra of the components due to their thermoluminescence properties, magneto-optical properties or magnetospin effects, photo- and thermochromism, pH-, piezo and solvatochromism, Raman enhancement effects (CRR) and fluorescence suppression when applying colloidal silver to the surface of the composition either gold or copper, and the determination of the strokes of the coding compositions is carried out based on the correspondence between the Raman spectra of the upper monomolecular layer or several monolayers of the composition at the point of intersection of the strokes of the Raman spectra of individual strokes. 3. The method for recognizing a coding composition by near-infrared Raman spectroscopy according to claim 2, characterized in that the coding composition according to claim 1 is applied on the brink of a gemstone, including in jewelry, in the process of non-destructive and precluding sample preparation in “Field conditions” for the diagnosis of falsification of natural stones with synthetic ones over the IR absorption bands of overtones of stretching OH vibrations.

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