Raman scattering enhancement device

Abstract

This utility model relates to optical sensors and can be used for analytical purposes, such as the qualitative and quantitative determination of ultra-trace quantities of a substance using Raman spectroscopy. A device for enhancing Raman scattering comprises a solid multilayer nanostructure containing a solid substrate with a smooth surface. Between the solid substrate and the multilayer nanostructure is a heat-modulating layer with a gradient thickness, over which a multilayer structure is formed. The layer comprises layers containing a plasmonic material component, oxidizer layers, and reductant layers. When exposed to energy, a self-propagating exothermic reaction occurs. This utility model improves the stability and selectivity of the device when studying complex mixtures for giant Raman spectroscopy. 6 fig.

Description

[0001] This utility model relates to the development of optical sensors. The device can be used for analytical purposes, such as the qualitative and quantitative determination of ultra-small quantities of substances using Raman spectroscopy.

[0002] There are solutions using a multicomponent film containing a plasmonic material component to obtain giant Raman scattering spectra. In Russian Patent No. 229846, a substrate for giant Raman scattering spectroscopy is fabricated by energetically influencing a multicomponent film containing a plasmonic material component and a material component to form an array of plasmonic material on top of the film [1].

[0003] International Patent No. 2012158201 presents a design of a substrate with a GCRS effect, consisting of a silicon substrate with a layer of SiO2 nanoparticles on the surface, the upper part of which and the spaces between which are covered with a GCRS-active layer of gold, with a thickness of 2 to 50 nm [2].

[0004] The closest technical solution is Russian Patent No. 2696899, which proposes the formation of a solid multilayer structure consisting of two SERS-active layers made from different nanoparticle arrays [3]. A disadvantage of this design is the degradation of the SERS-active layer upon exposure to the atmosphere after substrate fabrication. Furthermore, the plasmonic material array has identical geometric parameters across its entire surface, preventing the creation of differently selective zones on a single substrate.

[0005] The objective of the utility model is to increase the stability and selectivity of the device when studying complex mixtures for giant Raman spectroscopy.

[0006] To achieve the stated objective, a design of a device for giant Raman spectroscopy is proposed, consisting of a solid substrate with a smooth surface, a heat-modulating layer with a gradient thickness, on top of which a multilayer structure is formed, consisting of layers containing a component of plasmonic material, layers of an oxidizer and a reducing agent, upon the action of energy on which a self-propagating exothermic reaction occurs, leading to the formation of a supporting layer and an array of nanoparticles of plasmonic material on top of it.

[0007] Giant Raman spectroscopy (GRS) is a logical continuation of Raman spectroscopy and is distinguished by the fact that it uses substrates with a nanostructured surface (GERS substrates), which are capable of providing an increase in the Raman signal from the substance under study up to 10 12These substrates contain arrays of metallic or semiconductor nanoparticles, which, when exposed to incident light, generate a plasmon—an oscillating free electron gas. For specific wavelengths of incident laser radiation and nanoparticle sizes, a localized surface plasmon resonance (SPR) occurs, generating a high-intensity electromagnetic field that rapidly weakens with distance from the nanoparticle. Molecules within this field emit a significantly increased Raman radiation, significantly simplifying their detection.

[0008] Fig. 1 shows the stages of the proposed method for producing a substrate with express self-assembly of nanoparticles for obtaining giant Raman scattering spectra,

[0009] where 1 is a solid-state substrate; 2 is a thin film in the form of a multilayer structure consisting of layers containing a plasmonic material component, an oxidizer and a reducing agent; 3 is a supporting layer; 4 is an array of plasmonic material nanoparticles; 9 is a heat-modulating layer with a gradient in thickness.

[0010] Fig. 1a shows a section of the structure after deposition on a solid substrate 1 of a heat-modulating layer 9 with a gradient in thickness and a thin film in the form of a multilayer structure 2 consisting of layers containing a plasmonic material component, an oxidizer and a reducing agent.

[0011] Fig. 1b shows a section of the structure after a short-term local energy impact, which results in a self-propagating exothermic reaction between the oxidizer and reductant components and simultaneously forms a supporting layer 3 and an array of plasmonic material nanoparticles 4 on top of it.

[0012] Fig. 2 shows the stages of the proposed method for producing a substrate with express self-assembly of nanoparticles for obtaining giant Raman scattering spectra, in which the plasmonic material component is contained in the upper layer of a thin film in the form of a multilayer structure, where 5 is a thin film in the form of a multilayer structure consisting of alternating layers of an oxidizer and a reductant; 6 is a layer containing a plasmonic material component.

[0013] Fig. 2a shows a section of the structure after deposition on a solid substrate 1 of a heat-modulating layer 9 with a gradient thickness and a thin film in the form of a multilayer structure 5 consisting of alternating layers of an oxidizer and a reductant, and a layer 6 containing a component of a plasmonic material on top of it.

[0014] Fig. 2b shows a section of the structure after a short-term local energy impact, which results in a self-propagating exothermic reaction between the oxidizer and reductant components and simultaneously forms a supporting layer 3 and an array of plasmonic material nanoparticles 4 on top of it.

[0015] Fig. 3 shows the stages of the proposed method for producing a substrate with express self-assembly of nanoparticles in the presence of a mirror layer on a solid substrate for obtaining giant Raman scattering spectra, where: 7 is a mirror layer; 8 is an optically transparent supporting layer.

[0016] Fig. 3a shows a section of the structure after deposition on a solid substrate 1 of a heat-modulating layer 9 with a gradient in thickness, a mirror layer 7 and a thin film in the form of a multilayer structure 2 consisting of a layer or layers containing a component of a plasmonic material, an oxidizer and a reducing agent.

[0017] Fig. 3b shows a section of the structure after a short-term local energy impact, as a result of which a self-propagating exothermic reaction occurs between the components of the oxidizer and the reducing agent, and an optically transparent supporting layer 8 and an array of plasmonic material nanoparticles 4 are simultaneously formed on top of the mirror layer 7.

[0018] A distinctive feature of the utility model is that the use of a multilayer film allows for the long-term preservation of the plasmonic material component from contact and atmospheric oxidation. Until a short-term localized energy input is applied, the plasmonic material component is uniformly distributed within the thin film layer or layers as a multilayer structure. The short-term localized energy input leads to a self-propagating exothermic reaction between the oxidizing agent and the reducing agent, which results in the formation of an array of plasmonic material nanoparticles on the surface, simultaneously forming a supporting layer underneath.The advantage of using a gradient-thickness heat-modulating layer in the design is that by selecting the material and, accordingly, setting the layer's thermal conductivity to high or low, it is possible to form arrays with different geometric parameters, thereby creating zones with different selectivity for the analyzed solutions. This will increase the substrate's sensitivity.

[0019] Example 1.

[0020] The substrate for use in surface-enhanced Raman spectroscopy is a solid-state glass substrate with a heat-modulating Cu layer with a thickness ranging from 10 to 300 nm, a 1500 nm thick Al-Ni multilayer thin film layer consisting of alternating Al and Ni layers, each 50 nm thick, and a 50 nm thick layer of plasmonic Au material. Short-term local energy impact was implemented using an electric spark from a low-power piezoelectric generator, resulting in the formation of a supporting layer (AlNi) and an array of plasmonic Au nanoparticles with an average particle diameter in the range of 100 to 250 nm. After fabrication, the device was placed in a complex mixture of rhodamine 6G (R6G), malachite green (MG), and methylene blue (MB) solutions for 30 minutes, after which it was removed and dried in a fume hood.Raman spectrometer study showed that as the gradient layer thickness increased, R6G, MG, and MB exhibited the highest signal intensity, respectively.

[0021] The utility model eliminates the main shortcomings of the prototype, ensuring the stability and selectivity of the device through the use of a gradient-thickness heat-conducting or heat-insulating layer and a multilayer structure consisting of layers containing a plasmonic material component, layers of an oxidizer and a reducing agent, which allows the formation of an array of nanoparticles on the surface of the substrate.

[0022] Sources of information

[0023] 1. Russian Federation Patent No. 229846.

[0024] 2. International Patent No. 2012158201.

[0025] 3. Russian Federation Patent No. 2696899 - prototype.

Claims

A device for enhancing Raman scattering of light, including a solid multilayer nanostructure containing a solid substrate with a smooth surface, characterized in that between the solid substrate and the multilayer nanostructure there is a heat-modulating layer with a gradient in thickness, on top of which a multilayer structure is formed, consisting of layers containing a component of a plasmonic material, layers of an oxidizer and a reducing agent, upon the action of energy on which a self-propagating exothermic reaction occurs.

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