DEVICE AND METHOD FOR THE ANALYSIS OF A SOLID SAMPLE MATERIAL

Description

[0001] The invention relates to a device for analyzing a solid sample material by means of laser ablation of particles of the solid sample material into a carrier liquid according to claim 1.

[0002] Furthermore, the invention relates to a method for analyzing a solid sample material by means of laser ablation of particles of the solid sample material into a carrier liquid according to claim 13.

[0003] WO 2016 / 042165 A1 discloses a device in which an aerosol is generated from a solid sample by means of laser ablation.

[0004] US 2012 / 0079894 A1 shows an analytical system for laser ablation of a solid, wherein a suspension containing an analyte is transferred from an ablation cell into a mass spectrometer by means of a carrier gas.

[0005] In order to determine the elemental composition of solid samples with high accuracy, it is known in the art to dissolve the solid sample by acid or fusion digestion. The sample solution can then be analyzed using an elemental analytical method (e.g., flame or electrothermal atomic absorption spectroscopy, ICP-OES, ICP-MS). This method is suitable for materials that are easily soluble in acids, such as metals and their alloys. However, if the sample is chemically inert and difficult or insoluble in acids, labor-intensive methods such as microwave digestion or high-pressure ashing in combination with suitable reagents (e.g., with an oxidizing agent) must be used to convert the sample into a dissolved form. This property is particularly true for ceramic materials, which are very important in the production of modern functional materials.

[0006] To avoid the difficulties associated with transferring solids into solutions, direct solid analysis can be used. A variety of methods are available, such as X-ray fluorescence, scanning electron microscopy, spark spectrometry, and laser ablation ICP-MS. "inductively coupled plasma mass spectrometry" for "Inductively Coupled Plasma Mass Spectrometry" Substantial disadvantages of X-ray-based methods include limitations in the analysis of light elements, and in the case of ablative methods, the matrix dependence of signal generation and the associated need for matrix-matched standards. Such standards are not available for all classes of substances, especially for newly developed materials. Furthermore, the determination accuracy of most solid-state analysis methods is insufficient to determine, for example, the stoichiometry of new materials with sufficient precision.

[0007] LASIL offers a combination of solid and liquid analysis. "Laser Ablation of a Solid in Liquid" for "Laser ablation of a solid in a liquid" ). Here, the solid sample is placed in a liquid through which a focused and pulsed laser beam is fired. The laser beam hits the sample surface, causing nanoparticles of the sample to disperse in the liquid. This creates a so-called nanosol.

[0008] LASIL technology is used, for example, to produce nanoparticles. One such application is described in WO 2010 / 087869 A1. A solid sample in a container is covered with a layer of liquid several millimeters thick. The sample is exposed to a laser beam to generate metallic nanoparticles. A liquid stream is passed through the container so that the nanoparticles can be removed and collected. However, this setup would be unsuitable for chemical analysis.

[0009] LASIL has also been used sporadically for chemical analysis. Previously, a stationary droplet was applied to the sample surface before a laser beam was passed through the stationary droplet. After manually withdrawing the liquid using a pipette, the resulting sample nanosol was then analyzed using conventional ICP-MS for liquid analysis. This method is described, for example, in Douglas et al., "Laser Ablation of a Sample in Liquid - LASIL," J. Anal. At. Spectrom., 2011, 26, 1294.

[0010] A major advantage of LASIL is that matrix-matched standards are not required, and aqueous standard solutions can be used to quantify the obtained signal intensities. However, in the current experimental setup, the manual step of sample transfer into the measuring device represents a major limitation. Further disadvantages of the known method include potential contamination and the sedimentation of the generated particles during the transfer of the suspension to the measuring device.

[0011] Different analysis techniques are known from US 2012 / 0079894 A1, DE 10 2006 056 929 A1 and WO 2014 / 127034 A1.

[0012] The object of the invention is to alleviate or eliminate at least some of the disadvantages of the prior art. The invention therefore aims to improve the known "LASIL" devices and methods to enable a simpler and more precise analysis of the solid sample material.

[0013] This object is achieved by a LASIL device having the features of claim 1 and a method having the features of claim 13. Preferred further developments of the invention are specified in the dependent claims.

[0014] The LASIL device according to the invention includes an ablation cell with the sample holder for the solid sample material, with a liquid channel for the carrier liquid and with an entrance window made of a material permeable to the laser beam of the laser device, a supply line for supplying the carrier liquid into the liquid channel of the ablation cell, a discharge line for draining the suspension of particles of the solid sample material and the carrier liquid from the liquid channel of the ablation cell into the analysis device, and a dosing device for introducing a defined volume of a standard liquid into the supply line to obtain a calibration signal.

[0015] According to the invention, the fluid channel of the ablation cell is connected on one side to the supply line and on the other side to the outlet line for the carrier fluid. Accordingly, the ablation cell is designed as a flow-through cell through which the carrier fluid can continuously flow. The supply line and the outlet line can each be designed as a hose or pipe. The carrier fluid is conveyed via the supply line into the fluid channel of the ablation cell and, after flowing through the fluid channel, can be supplied to the analysis device via the outlet line. Preferably, the outlet line is directly connected to an inlet of the analysis device. The ablation or washout cell also has a laser beam entrance window made of a material permeable to the laser beam of the laser device.The laser beam is coupled into the ablation cell through the entrance window, where it passes through the carrier fluid coming from the feed line in the fluid channel and impinges on the surface of the solid sample material. This dissolves particles, particularly nanoparticles, from the surface of the solid sample material, creating a suspension of particles of the solid sample material and the carrier fluid, particularly in the form of a nanosol.

[0016] The suspension is then fed via the outlet of the analysis device, in which, in particular, the chemical composition of the solid sample material is determined. The design according to the invention offers the advantage, on the one hand, that the manual transfer of the drop containing the nanoparticles to the measuring device, as required in the prior art, is no longer necessary. This eliminates a potential source of contamination. Furthermore, the time and effort required per measurement are reduced. The device can therefore be used for routine examinations. Another advantage is that the liquid channel is closed off by the entrance window on the side facing away from the sample holder. This ensures that the particles of the solid sample material generated by the laser beam can be essentially completely discharged via the outlet of the ablation cell and fed to the analysis device.In this way, in particular, a quantitative analysis of the solid sample material in the analysis device is made possible.

[0017] To enable quantitative analysis of the solid sample material, a dosing device, particularly one with a dosing loop, is provided for introducing a defined volume of a standard liquid into the feed line. The standard liquid contains the same analyte as the solid sample material to be analyzed. In a separate measurement, the standard liquid can be introduced into the feed line using the dosing device, passed through the ablation cell, and analyzed in the analysis device. This produces a calibration signal, which can be used to calibrate the measurement signal for the particles of the solid sample material obtained by laser ablation. This advantageously allows for quantitative and stoichiometric analyses of the solid sample material.

[0018] For the purposes of this disclosure, location and direction references such as "top," "bottom," "vertical," "horizontal," etc., refer to the intended operating state of the LASIL device.

[0019] The carrier liquid can preferably be water or a substance that is liquid at room temperature, in particular an organic solvent, for example acetonitrile or ethanol, or a mixture thereof. Dissolved additives, such as metal salts, are also preferably added to the carrier liquid.

[0020] According to a particularly preferred embodiment, the ablation cell comprises, on the one hand, a housing with the liquid channel and the entrance window, and, on the other hand, the sample holder with the solid sample material, wherein the housing is placed on the solid sample material in the operating state. Accordingly, in this embodiment, the ablation cell comprises two connectable and separable units, wherein one unit of the ablation cell is formed by the housing with the liquid channel and the entrance window, and the other unit is formed by the sample holder with the solid sample material. To prepare for analysis, the user places the housing on the solid material, whereby the liquid channel is formed between the top side of the solid sample material and the bottom side of the housing. After analysis, the housing can be removed from the solid sample again.

[0021] This design is particularly advantageous for several reasons. Firstly, the housing can be placed, especially pressed, onto different, particularly flat, samples to form the fluid channel for ablation. This provides particular flexibility in analysis, as very different sample types can be analyzed. Secondly, improved washout behavior can be achieved. It is possible to minimize the effective area through which fluid flows, since the fluid does not have to flood the entire sample, but only a section of the sample adjacent to the fluid channel.

[0022] To form the fluid channel on the underside of the housing during assembly of the ablation cell, the housing preferably has a section of the supply line and / or a section of the discharge line, wherein the section of the supply line and / or the section of the discharge line are each connected to the fluid channel formed in the operating state on the underside of the housing facing the solid sample material. Accordingly, the section of the supply line (or, correspondingly, the section of the discharge line) each opens into an opening on the underside of the housing, so that when the housing is placed on the solid sample material, the fluid channel is formed between the top side of the solid sample material and the underside of the housing.

[0023] To enable reliable analysis, a detachable connection, in particular a clamp or screw connection, is preferably provided to hold the housing on the solid sample material in the operating state. The detachable connection is preferably designed so that the housing is pressed against the upper side of the solid sample material in the operating state.

[0024] To ensure the sealing of the fluid channel during operation, in a preferred embodiment, the housing is provided with a sealing element on the underside facing the solid sample material, which is in sealing contact with the solid sample material during operation. When detached, the housing is open at the bottom. When placed on the solid sample, the fluid channel is formed between the underside of the housing, the sealing element, and the top side of the solid sample material.

[0025] To form the fluid channel in the operating state, the height of the fluid channel preferably corresponds essentially to the thickness of the sealing element. The height or thickness is measured in a direction perpendicular to the direction of fluid flow in the fluid channel.

[0026] In an alternative embodiment, the sample holder for the solid sample has a section of supply and discharge line. In this embodiment, the sample holder has a chamber for inserting the solid sample. In the operating state, the chamber is closed off at the top by the entrance window.

[0027] In a further preferred embodiment, the supply line has an end section running essentially perpendicular to the main plane of the entrance window, and the discharge line has an end section running essentially perpendicular to the main plane of the entrance window. The end section of the supply line is in fluid communication with one end of the fluid channel in the ablation cell, and the end section of the discharge line is in fluid communication with the other end of the fluid channel in the ablation cell. This embodiment is particularly simple in design.

[0028] According to a particularly preferred embodiment, the fluid channel between the sample holder and the entrance window has a substantially constant height of 10 µm to 1 mm, in particular of 50 µm to 200 pm. In this range of the height of the fluid channel, a flow velocity sufficient for the removal of the particles can be ensured, while the laser power impinging on the sample surface is attenuated only to a suitable extent.

[0029] In order to enable a continuous analysis of the solid sample material, the supply line for the carrier liquid is connected to a pumping device in a particularly preferred embodiment, which pumping device is preferably designed to provide a substantially constant volume flow of the carrier liquid through the liquid channel of the ablation cell.

[0030] To enable quantitative analysis of the solid sample material, a dosing device, preferably with a dosing loop, is provided for introducing a defined volume of a standard liquid into the feed line. The standard liquid contains the same analyte as the solid sample material to be analyzed. In a separate measurement, the standard liquid can be introduced into the feed line with the help of the dosing device, passed through the ablation cell, and analyzed in the analysis device. This produces a calibration signal with which the measurement signal for the particles of the solid sample material obtained by laser ablation can be calibrated. This advantageously allows quantitative and stoichiometric analyses of the solid sample material to be carried out.

[0031] For a reliable, structurally simple design, the dosing device preferably comprises a multi-way valve, in particular a 6-way valve. As is known in the prior art, the 6-way valve has two switching states. In one switching state, a predetermined amount of standard fluid is added to the dosing loop. In the other switching state, the amount of standard fluid held in the dosing loop is pumped into the supply line for the ablation cell. An example of such a 6-way valve is described in US 2011 / 186511 A1. Alternatively, the dosing device can comprise an 8-way valve or a 10-way valve.

[0032] To enable a spatially resolved analysis of the solid sample material, a device is preferably provided for generating a relative movement between the ablation cell and the laser device in the longitudinal direction (x) and / or in the transverse direction (y) of the sample holder and / or in the height direction (z) substantially perpendicular to the longitudinal (x) and transverse directions (y). Depending on the design, a qualitative, and preferably also quantitative, analysis of the solid sample material can be carried out along the main plane of the solid sample material, i.e., in the x and / or y directions. Advantageously, this allows a spatial resolution of the measurement signal of the analysis device to be achieved. For example, the composition of the solid sample material can be examined as a function of the x and / or y position in the main plane of the solid sample material.

[0033] In a preferred embodiment, the device comprises a stage movable in the x-, y-, and / or z-direction for supporting the ablation cell. In this embodiment, the laser device can be arranged stationary.

[0034] For elemental analysis of the solid sample, it is advantageous if the analysis device comprises an optical emission spectrometer or a mass spectrometer, in particular each with an excitation and / or ionization source. An ICP module can be provided as the excitation and / or ionization source.

[0035] The corresponding procedure includes the steps: Feeding the carrier fluid into a fluid channel of an ablation cell via a feed line; conveying the carrier fluid through the fluid channel of the ablation cell, wherein the particles of the solid sample material are ablated into the carrier fluid by irradiation with the laser beam; draining the suspension of particles of the solid sample material and the carrier fluid from the fluid channel of the ablation cell, wherein the measurement signals of the analysis device are quantified using a standard fluid, which is introduced into the feed line for the carrier fluid via a dosing device for calibration.

[0036] The particles of the solid sample material can then be analyzed, particularly with regard to their elemental composition.

[0037] In a preferred embodiment, the following steps are also carried out for a spatially resolved analysis of the solid sample material: Moving the solid sample material relative to the laser beam in the longitudinal direction (x) and / or in the transverse direction (y) of the solid sample material and / or in the height direction (z) of the solid sample material; analyzing the particles of the solid sample material as a function of an x-position and / or a y-position and / or a z-position of the solid sample material relative to the laser beam.

[0038] Furthermore, it is preferred if the following steps are carried out: Analyzing a defined volume of a standard liquid containing an analyte of the solid sample material; calibrating a first measurement signal obtained when analyzing the particles of the solid sample material using a second measurement signal obtained when analyzing the defined volume of the standard liquid.

[0039] Depending on the composition of the solid sample, several standard liquids can be analyzed, each containing a specified amount of at least one analyte from the solid sample. By selecting the chemical elements contained in the standard solution and / or their concentrations, an application-specific adaptation to the respective question is possible.

[0040] In this embodiment, the method may in particular comprise the further step: Determining a ratio between the amount of a first analyte of the solid sample material and the amount of a second analyte of the solid sample material.

[0041] The solid sample material to be analyzed can be, for example, a semiconductor, a glass, or a ceramic material. To analyze the defined volume of the standard liquid, a dosing loop connected to a 6-way valve is preferably used.

[0042] The invention is further explained below using a preferred embodiment, to which it is not intended to be limited. Fig. 1 shows a block diagram of a device according to the invention for analyzing a suspension of particles of a solid sample material and a carrier liquid obtained by laser ablation; Fig. 2 shows a diagrammatic view of an ablation cell of the device according to Fig. 1 , wherein the ablation cell is connected to a supply line and a discharge line for the carrier fluid; Fig. 3 shows a schematic side view of the ablation cell according to Fig. 2 ; Fig. 4 shows a detailed view of the Fig. 3 framed section of the ablation cell; Fig. 5 shows in a diagram the signal-time curve of a Sr and a Ti emission line in an analysis device of the device according to Fig. 1 ; Fig. 6shows an alternative embodiment of the LASIL device 1.

[0043] Fig. 1 shows a device 1 for analyzing a solid sample material 2 (cf. Fig. 4 ) by laser ablation of particles 3 of the solid sample material 2 into a carrier liquid. The device 1 has a sample holder 5 (cf. Fig. 4) for arranging the solid sample material 2 covered with the carrier liquid. Furthermore, a laser device 6 (only schematically indicated) is provided for emitting a focused and pulsed laser beam 7. The laser beam 7 causes particles 3 to detach from the surface of the solid sample material 2, thereby creating a suspension of particles 3 of the solid sample material 2 and the carrier liquid. The LASIL device 1 also has an analysis device 8 for analyzing the suspension of particles 3 of the solid sample material 2 and the carrier liquid. The analysis device 8 can have an optical emission spectrometer with an ionization source, in particular in the form of an ICP-OES (inductively coupled plasma optical emission spectrometry). Alternatively, an ICP-MS (inductively coupled plasma optical emission spectrometry) can be used."inductively coupled plasma mass spectrometry" for "mass spectrometry with inductively coupled plasma").

[0044] In the embodiment shown, the release of the particles 3 of the solid sample material 2 is carried out in an ablation or washout cell 9, in which the sample holder 5 for the solid sample material 2 is accommodated. The ablation cell 9 also has a liquid channel 10 with a closed cross-section, through which the carrier liquid is conveyed. Furthermore, a supply line 11 for supplying the carrier liquid into the liquid channel 10 of the ablation cell 9 (see arrow 20 in Fig. 2 , 4 ) and a discharge line 12 for discharging the suspension of particles 3 of the solid sample material 2 and the carrier liquid from the liquid channel 10 of the ablation cell 9 into the analysis device 8 (cf. arrow 21 in Fig. 2 , 4 ) is provided.

[0045] As from Fig. 2 to 4As can be seen, the ablation cell 9 has an entrance window 13 made of a (solid) material permeable to the laser beam 7 of the laser device 6, for example CaF 2 , quartz glass or borosilicate glass. In the embodiment of the Fig. 2 to 4 The entrance window 13 is held to the sample holder 5 of the ablation cell 9 via a detachable connection to enable an exchange of the solid sample material 2 below the entrance window 13. Furthermore, in this embodiment, the liquid channel 10 is formed within the sample holder 5.

[0046] Accordingly, the laser beam 7 passes through the entrance window 13, penetrates the carrier liquid, and strikes the surface of the solid sample material 2, releasing particles 3 of the solid sample material 2. The liquid channel 10 between the sample holder 5 and the entrance window 13 has a substantially constant height (relative to the transport direction of the carrier liquid along the x-axis) of 10 µm to 1 mm, in particular of 50 µm to 200 pm. The height of the liquid channel refers to the extension of the liquid channel in the z-direction, i.e., in a direction substantially perpendicular to the main plane of the sample holder, which is spanned by the x- and y-axes.

[0047] The resulting suspension consisting of the carrier liquid and the (nano-)particles 3 of the solid sample material 2 is fed to the analysis device 8, in which qualitative or quantitative analyses of the particles 3 are carried out.

[0048] As from Fig. 1 As can also be seen, the supply line 11 for the carrier fluid is connected to a pumping device 14, with which carrier fluid is pumped from a fluid reservoir 15 into the supply line 11 for the ablation cell 9. The pumping device 14 effects a substantially constant volume flow of the carrier fluid through the fluid channel 10 of the ablation cell 9, which is matched to the capacity of the analysis device 8.

[0049] As from Fig. 1As can also be seen, a dosing device 16 with a dosing loop 17 is also provided for introducing a defined volume of a standard liquid into the supply line 11. In the embodiment shown, the dosing device 16 has a 6-way valve 18.

[0050] As from Fig. 1 As can also be seen, in the embodiment shown, a device 19 is provided for generating a relative movement between the ablation cell 9 and the laser device 6 in the longitudinal direction x, in the transverse direction y of the sample holder 5 running perpendicular thereto and in the height direction z perpendicular to the longitudinal x and transverse direction y.

[0051] In Fig. 3, 4The ablation cell 9 is shown. Accordingly, the carrier liquid is conveyed from the supply line 11 through the essentially horizontal liquid channel 10. Meanwhile, the surface of the solid sample material 2 is irradiated with the laser beam 7, whereby particles 3 of the solid sample material 2 are absorbed into the carrier liquid. The resulting suspension is fed to the analysis device 8. As can be seen from Fig. 3As can be seen, the supply line 11 has an end section 22 running essentially perpendicular to the main plane of the entrance window 13, and the discharge line 12 has an end section 23 running essentially perpendicular to the main plane of the entrance window 13. The end section 22 of the supply line 11 is fluidly connected to one end of the fluid channel 10 in the ablation cell 9. Accordingly, the end section 23 of the discharge line 12 is fluidly connected to the other end of the fluid channel 10 in the ablation cell 9.

[0052] With the device 1 described above, a method for analyzing a solid sample material 2 by laser ablation of particles 3 of the solid sample material 2 into a carrier liquid can be carried out, which method comprises at least the following steps: Providing the solid sample material 2 and a layer of carrier liquid covering the solid sample material 2, irradiating the solid sample material 2 with a laser beam 7 such that a suspension of particles 3 of the solid sample material 2 and the carrier liquid is generated, analyzing the suspension of particles 3 of the solid sample material 2 and the carrier liquid, feeding the carrier liquid into a liquid channel 10 of a flow-through ablation cell 9; conveying the carrier liquid through a liquid channel 10 of an ablation cell 9, wherein the particles 3 of the solid sample material 2 are ablated into the carrier liquid by irradiation with the laser beam 7; and draining the suspension of particles 3 of the solid sample material 2 and the carrier liquid from the liquid channel 10 of the ablation cell 9.

[0053] To achieve a spatially resolved analysis of the solid sample material 2, the steps Moving the solid sample material 2 relative to the laser beam in the longitudinal direction x and / or in the transverse direction y of the solid sample material 2 and / or in the height direction z of the solid sample material 2; analyzing the suspension of particles 3 of the solid sample material 2 and the carrier liquid as a function of an x-position and / or a y-position and / or a z-position of the solid sample material 2 relative to the laser beam 7 be performed.

[0054] Accordingly, an analytical method is provided that combines the advantages of solid and liquid analysis. The sample is located in a specially designed ablation or washout cell 9, which is flushed with a preferably essentially constant flow of carrier liquid, in particular water or a preferably dilute acid.

[0055] The ablation cell 9 is formed with an entrance window 13, which is permeable to the wavelength of the laser device 6. When the laser beam 7 is directed through the entrance window 13 onto the sample surface, extremely fine particles 3 are created, which form a nanosol in the liquid flow. This suspension is transported from the ablation cell 9 and directed to an analysis device 8 in the form of an ICP-OES or ICP-MS device to record a transient analyte signal. The measurement signals can be quantified using aqueous standards (standard liquids). The aqueous standards can be introduced into the supply line 11 for the carrier liquid via a dosing device 16, in particular in the form of a flow injection system with a dosing loop 17. This process can be automated with the device 1, enabling sample analysis without manual intervention.This makes it particularly easy to analyze difficult-to-dissolve materials, such as ceramics. The method also offers significant advantages for other samples. The only basic requirement is that these samples must be insoluble in the carrier fluid used. Example

[0056] The method was applied to analyze the stoichiometry of a SrTiO 3 layer produced by pulsed laser deposition (PLD). The SrTiO 3 layer was deposited on an yttrium-stabilized zirconium oxide platelet as a substrate. The layer thickness is approximately 500 nm.

[0057] Fig. 5 shows the signal-time curve of a Sr emission line 24 and a Ti emission line 25 during a point ablation of the sample with a laser beam 7 with a diameter of 200 µm and a laser power of 1.83 mJ. Ten laser pulses were emitted onto the sample. Fig. 5The sufficient signal intensity for both analytes of interest as well as good washout behavior of the ablation cell 9 can be seen. By calibration using the dosing device 16, it can be determined that the total ablated and detected amount of sample material 2 is approximately 140 ng.

[0058] Using the standard liquids introduced via the dosing device 16, the relative composition of the sample material 2 can also be determined. By averaging six individual measurements, a ratio of 1.000 ± 0.017 (Sr) to 0.988 ± 0.017 (Ti) was determined. The obtained values ​​do not differ significantly from the 1:1 ratio. Therefore, it can be concluded that a stoichiometric layer is present. This example demonstrates an application of the online LASIL method, which can achieve significant time savings compared to the sample preparation required for conventional liquid analysis. The SrTiO3 layer could only be dissolved through a complex fusion process. In addition, a liquid measurement would not exceed the precision of the demonstrated measurements.

[0059] Fig. 6shows an alternative embodiment of the LASIL device 1, wherein only the differences to the embodiment of the Fig. 1 to 5 is entered into.

[0060] In the embodiment of the LASIL device 1 according to Fig. 1 to 5 the solid sample material 2 is placed in a chamber 5a (cf. Fig. 4 ) of the sample holder 5, which also contains the liquid channel 10. The chamber 5a can be designed in particular as a trough-shaped depression on the upper side of the sample holder 5.

[0061] In preparation for the measurement, the solid sample material 2 is placed in the chamber 5a with the entrance window 13 removed before the liquid channel 10 is closed with the entrance window 13.

[0062] According to Fig. 6the ablation cell 9 has, on the one hand, a housing 9a with the liquid channel 10 and the entrance window 13 and, on the other hand, the sample holder 5 for the solid sample material 2. The housing 9 with the liquid channel 10 and the entrance window 13 and the sample holder 5 with the solid sample material 2 are separate from one another. In this embodiment, the sample holder 5 is free of the liquid channel 13. For example, the sample holder 5 can thus be formed by a base, in particular a plate-shaped base. In this embodiment, the housing 9a thus forms the actual ablation cell 9, which in the intended operating state, i.e. during ablation, is placed on the solid sample material 2. For this purpose, the housing 9a is provided on the underside facing the solid sample material 2 with a sealing element 26, which is in sealing contact with the solid sample material 2 in the operating state.The sealing element 26 is preferably formed from an elastomer, in particular polymethyl methacrylate (PMMA) or silicone. Furthermore, a detachable connection, in particular a clamp or screw connection, can be provided to firmly hold the housing 9 on the solid sample material 2 in the assembled operating state. The solid sample material 2 is preferably flat, in particular having a planar upper surface.

[0063] In this embodiment, compared to the Fig. 1 to 5 Greater flexibility is achieved in the analysis of different samples, since the sample does not have to fit into the chamber 5a of the sample holder 5. The analysis principle remains unchanged.

[0064] As from Fig. 5As can be seen, the housing 9a has a section 11a of the supply line 11 upstream of the liquid channel 10 in the direction of flow and a section 12a of the discharge line 12 downstream of the liquid channel 10 in the direction of flow. The supply line 11 and the discharge line 12 each open into the liquid channel 10, which in the embodiment shown is formed on the underside of the housing 9a. In the embodiment shown, the liquid channel 10 is delimited by the underside of the housing 9a, the sealing element 26 and the surface of the solid sample material 2. As previously described, a liquid stream from the supply line 11 flows through the liquid channel 10. In the process, a liquid film 3 is generated on the sample surface. In the embodiment shown, the height of the liquid film essentially corresponds to the thickness of the sealing element 26, which in the operating state is located between the housing 9a and the sample surface.The sealing element preferably has a thickness of 10 µm to 1 mm, in particular of 50 µm to 200 pm. The sealing element 26 preferably extends substantially over the entire underside of the housing 9a, but with a recess corresponding to the liquid channel 10. Above the liquid channel 10 is the optical entrance window, for example made of CaF 2 or quartz glass, which has a high transparency for the wavelength of the laser used. When the laser beam 7 strikes the sample surface, an optical waveguide is formed (as previously described in connection with . Fig. 1 to 5 described) leads to the formation of nanoparticles from the sample material, which are transported away by the liquid flow in the direction of the outlet 12.

[0065] The housing 9a is preferably made of a plastic material, so that, in particular, no metallic contaminants are released into the liquid to be analyzed. Preferred plastic materials are chemically inert; for example, polyoxymethylene (POM) or polytetrafluoroethylene (PTFE) are suitable.

[0066] According to Fig. 6 The housing 9 has a recess 27, which, in the embodiment shown, tapers downwards in sections in a funnel shape. The inlet window 13, which closes off the fluid channel 10 at the top, is located on the underside of the recess.

[0067] The design of the Fig. 6It is characterized by its particularly high flexibility and user-friendliness. Advantageously, it achieves particularly favorable washout behavior. It is possible to minimize the effective area through which the liquid flows, since the entire sample no longer needs to be flushed with the liquid.

Claims

1. A device (1) for analysing a solid sample material (2) by means of laser ablation of particles (3) of the solid sample material (2) in a carrier liquid, comprising: - a sample holder (5) for positioning the solid sample material (2) covered with the carrier liquid; - a laser device (6) for irradiating the solid sample material (2) with a laser beam (7) in a manner such that a suspension of particles (3) of the solid sample material (2) and of the carrier liquid can be produced, - an analytical device (8) for analysing the particles (3) of the solid sample material (2), - an ablation cell (9) having the sample holder (5) for the solid sample material (2), having a liquid channel (10) for the carrier liquid and having an entry window (13) produced from a material that is transparent to the laser beam (7) of the laser device (6), - a supply line (11) to supply the carrier liquid to the liquid channel (10) of the ablation cell (9), and - a discharge line (12) to discharge the suspension of particles (3) of the solid sample material (2) and of the carrier liquid from the liquid channel (10) of the ablation cell (9) to the analytical device (8) characterized by - a dosing device (16) for introducing a defined volume of a standard liquid into the supply line (11) to obtain a calibration signal.

2. The device (1) as claimed in claim 1, characterized in that the ablation cell (9) on the one hand comprises a housing (9a) with the liquid channel (10) and the entry window (13) and on the other hand comprises the sample holder (5) with the solid sample material (2), wherein in the operational condition, the housing (9a) is positioned onto the solid sample material (2).

3. The device (1) as claimed in claim 2, characterized in that the housing (9a) comprises a section (11a) of the supply line (11) and / or a section (12a) of the discharge line (12), wherein the section (11a) of the supply line (11) and / or the section (12ab) of the discharge line (12) are respectively connected to the liquid channel (10) formed on the underside of the housing (9a) which underside faces the solid sample material (2) in the operational condition.

4. The device (1) as claimed in claim 2 or claim 3, characterized in that a releasable connection, in particular a clamp or screw connection, is provided in order to retain the housing (9a) on the solid sample material (2) in the operational condition.

5. The device (1) as claimed in any one of claims 2 to 4, characterized in that the housing (9a) is provided with a sealing element (26) on the underside facing the solid sample material (2) which sealing element (26) in the operational condition is in sealing contact with the solid sample material (2).

6. The device (1) as claimed in claim 5, characterized in that the height of the liquid channel (10) essentially corresponds to the thickness of the sealing element (26).

7. The device (1) as claimed in any one of claims 1 to 6, characterized in that the liquid channel (10) between the sample holder (5) and the entry window (13) comprises an essentially constant height of 10 µm to 1 mm, in particular of 50 µm to 200 µm.

8. The device (1) as claimed in any one of claims 1 to 7, characterized in that the supply line (11) for the carrier liquid is connected to a pump device (14), which pump device (14) is preferably configured in a manner such that an essentially constant volumetric flow of the carrier liquid is provided through the liquid channel (10) of the ablation cell (9).

9. The device (1) as claimed in any one of claims 1 to 8, characterized in that a dosing device (16) comprises a dosing loop (17) for introducing a defined volume of a standard liquid into the supply line (11).

10. The device (1) as claimed in claim 9, characterized in that the dosing device (16) comprises a multi-way valve (18), in particular a 6-way valve.

11. The device (1) as claimed in any one of claims 1 to 10, characterized in that a device (19) is provided for producing a relative movement between the ablation cell (9) and the laser device (6) in the longitudinal direction (x) and / or in the transverse direction (y) of the sample holder (5) and / or in the height direction (z) essentially perpendicular to the longitudinal direction (x) and transverse direction (y).

12. The device (1) as claimed in any one of claims 1 to 11, characterized in that the analytical device (8) comprises an optical emission spectrometer or a mass spectrometer, in particular respectively with an excitation source and / or ionisation source.

13. A method for analysing a solid sample material (2) by means of laser ablation of particles (3) of the solid sample material (2) in a carrier liquid, with the following steps: - providing the solid sample material (2) and a layer of the carrier liquid which covers the solid sample material (2), - irradiating the solid sample material (2) with a laser beam (7) in a manner such that a suspension of particles (3) of the solid sample material (2) and of the carrier liquid is produced, - analysing the particles (3) of the solid sample material (2) with the aid of an analytical device (8), - supplying the carrier liquid to a liquid channel (10) of an ablation cell (9) through a supply line (11); - conveying the carrier liquid through the liquid channel (10) of the ablation cell (9), wherein the particles (3) of the solid sample material (2) are ablated into the carrier liquid by irradiation with the laser beam (7); - discharging the suspension of particles (3) of the solid sample material (2) and of the carrier liquid from the liquid channel (10) of the ablation cell (9), characterized in that - the measurement signals of the analytical device (8) are quantified with the aid of a standard liquid, which is introduced for calibration through a dosing device (16) into the supply line (11) for the carrier liquid.

14. The method as claimed in claim 13, further characterized by the following steps: - moving the solid sample material (2) relative to the laser beam (7) in the longitudinal direction (x) and / or in the transverse direction (y) of the solid sample material (2) and / or in the height direction (z) of the solid sample material (2); - analysing the particles (3) of solid sample material (2) as a function of an x-position and / or a y-position and / or a z-position of the solid sample material (2) relative to the laser beam (7).