User-exchangeable ablation cell interface for varying LA-ICP-MS peak widths

Abstract

In one embodiment, a laser ablation system can include a laser ablation cell and at least one pair of particle collection-transport tube interfaces. The laser ablation cell can be configured to ablate a sample or other material, and the laser ablation cell can include a laser unit. The at least one pair of particle collection-transport tube interfaces can be configured to collect the ablated sample and direct the ablated sample to an analysis unit. A selected particle collection-transport tube interface can be received by the laser ablation cell and mounted on the laser unit. The at least one pair of particle collection-transport tube interfaces can be configured to be interchangeable.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Provisional Patent Application No. 62 / 959,865, filed January 10, 2020, and entitled “USER-EXCHANGEABLE ABLATION CELL INTERFACE FOR VARIING LA-ICP-MS PEAK WIDTH.” [Background technology]

[0002] Laser Ablation Inductively Coupled Plasma Mass Spectroscopy (LA-ICP-MS) or Laser Ablation Inductively Coupled Plasma Optical Emission Spectroscopy (LA-ICP-OES) techniques can be used to analyze the composition of a target (e.g., a solid or liquid target material). Often, a sample of the target is provided to the analysis system in the form of an aerosol (i.e., a suspension of solid and possibly liquid particles and / or vapor in a carrier gas, such as helium gas). The sample is typically generated by placing the target in a laser ablation chamber, i.e., introducing a flow of carrier gas into the chamber and ablating a portion of the target with one or more laser pulses to generate a plume (hereinafter referred to as "target material") containing particles and / or vapor suspended in the carrier gas that are emitted from the target or are otherwise generated. The target material entrained in the flowing carrier gas is transported to the analysis system via a transport conduit to an ICP torch, where it is ionized. The plasma containing the ionized particles and / or vapor is then analyzed by an analytical system such as an MS, QES, isotope ratio mass spectrometry (IRMS), or electrospray ionization (ESI) system.

[0003] The detailed description will now be made with reference to the accompanying drawings. [Brief description of the drawings]

[0004] [Figure 1]FIG. 2 illustrates a front isometric view of a laser ablation cell for use with a laser ablation spectroscopy measurement system according to an exemplary embodiment of the present disclosure. [Diagram 2] FIG. 2 is a top isometric partial view of a laser ablation cell employing a first particle collection-transport tube interface for use with the laser ablation cell of FIG. 1 . [Diagram 3] FIG. 2 is a top isometric partial view of a laser ablation cell employing a second particle collection-transport tube interface for use with the laser ablation cell of FIG. 1 . DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0005] Aspects of the present disclosure are described more fully hereinafter with reference to the accompanying drawings, which form a part hereof and which show exemplary features. Features may, however, be embodied in many different forms and should not be construed as being limited to the combinations set forth herein. Rather, these combinations are provided so that this disclosure will be full and complete, and will fully convey its scope.

[0006] (overview) Different applications of LA-ICP-MS may require different aerosol transport capacities. The aerosol transport capacity is determined by the geometry of the gas flow in the ablation cell (around the ablation site), in the transport region (connection tubes to the ICP-MS) and / or even in the ICP itself. For example, a "bulk analysis" application may require a very stable stream of particles, where particles generated from one laser pulse overlap with those generated from subsequent pulses during transport. This can be achieved if the peak width (mainly due to the washout time) of the typical laser frequency used is on the order of 1 second. This results in a more uniform aerosol flow and a stable signal in the ICP-MS. To achieve such a time-spanning peak width, the aerosol can be subjected to the presence of some dead volumes and a low gas flow velocity regime where dispersion can occur, thereby having the effect of broadening the peak.

[0007] When the analyst requires spatial interrogation of a sample, such as during elemental imaging (lateral profiling) and depth profiling, it is desirable to avoid mixing of particles caused by subsequent laser pulses, as this can result in loss of spatial resolution. Typically, in such imaging applications, a total peak width in the range of 1-100 ms (milliseconds) is desired, with shorter peak widths providing higher spatial resolution. This can be achieved by minimizing dead volumes and transporting the aerosol in a high gas flow velocity regime.

[0008] Ablation cell and transport techniques have historically been optimized for either "bulk analysis" or "spatial analysis." Ablation cells for bulk analysis have a dead volume designed to trap the aerosol but allow some dispersion. Additionally, the transport tube has a large inner diameter (e.g., 4 mm (millimeters)) to allow dispersion to occur during transport and achieve the desired level of mixing / smoothing. The aerosol can be deposited within a TCP torch. The TCP torch also has a very large injector diameter, which facilitates the desired level of dispersion.

[0009] Ablation cells optimized for spatial interrogation typically eliminate / reduce dead volume and draw the aerosol very quickly into the transport region to minimize dispersion. The transport tubes typically have small internal diameters (e.g., <2mm) to facilitate fast gas flow rates and minimize dispersion and peak broadening. Small diameter tubes extend as far into the ICP as possible to minimize "in torch" dispersion.

[0010] There are various challenges to overcome. One challenge is that these different requirements generally require different ablation cells. Switching out the entire ablation cell for different applications is not an ideal solution because a large number of (expensive) cells are required and switching can be complicated and time consuming. In addition to generally requiring different ablation cells for different applications, the current state of the art typically requires matching and changing the diameter of the transport tube, which does not provide the level of control or magnitude of change desired (e.g., generally cannot go from 1 ms to 1 s). And / or using an insert to "plug" and minimize the dead volume in the ablation cell, i.e., provide a design for a second volume (sometimes called a cup) to capture the aerosol and direct it directly into the transport tube. Similarly, using this insert does not provide the desired level of change, because it requires a significant change in the design of this second volume (or cup), which cannot be practically achieved with the insert. The Helex cell by Teledyne CETAC is a good example, offering a variety of inserts for the cup. However, these various inserts at most only change the peak width from 1 to several hundreds of ms.

[0011] In view of these challenges, embodiments of the present system provide a single ablation cell that is designed to allow a user / analyst to change between two or more configurations / modes by simply swapping out the entire particle collection-transport tube interface associated with the ablation cell. For example, one particle collection-transport tube interface can be used to facilitate a high speed / imaging mode, such that the aerosol is rapidly captured within a narrow inner diameter transport region (tube). Another particle collection-transport tube interface can be used to facilitate an analysis mode, in which the interface is utilized to capture the aerosol into a standard dead volume (e.g., a few milliliters (ml)) cup before it enters a wider inner diameter transport region. The interface is a complete assembly and can be switched in minutes. It is understood that other interfaces facilitating yet other modes can be used, so long as they are compatible with the ablation cell (e.g., overall size / shape, connection location).

[0012] In the second aspect, a key challenge in high-speed LA-ICPMS plume collection is the control of the sample and ablation faces relative to the collection orifice. We observed the dynamic interaction of the gas flow around the ablation site as a function of the distance from the surface of the ablation face to the collection orifice. When the distance is large, the travel distance and travel time of the ablation plume can increase in the low flow velocity region between the ablation and collection tubes. An important note is that the LA-ICPMS signal width is directly affected by the total travel time due to the diffusion of nanoparticles in the gas suspension. If the distance is too small, the total flow may be limited to reach the output orifice, and the capture efficiency of the particle plume may decrease.

[0013] Studies performed on this system have shown that the ideal distance from the sample face to the collection port is approximately 100 to 300 microns (μm). This distance can be optimized during setup and maintained during the LA-ICPMS experiment.

[0014] An additional challenge is locating the sample face close to the output orifice. In a typical 3-axis system, X- and Y-axis control is used to move the sample under the laser objective, which moves in the Z-axis plane to provide an adjustable focal position for samples of different heights. The geometry of the sample-to-sniffer distance can vary by more than a few hundred microns for a given sample height, potentially causing inadvertent scraping of the corresponding sample across and damaging it during pattern planning.

[0015] In standard slow collection, if we were to introduce the ability for the user to change from fast to slow plume collection, the sample to collection port distance must be considered. Slow plume collection requires a different and much larger distance between the sample face / ablation plane and the collection port due to the different collection port geometry. These requirements for different sample plane heights require changes in the focal plane of the laser as well as the sample to output distance.

[0016] (Example) 1-3 show a laser ablation system 100 according to the present disclosure. In one embodiment, the laser ablation system 100 can include a laser ablation cell 105 for ablating a sample or other material, a laser unit 108, and a pair of interchangeable particle collection-transport tube interfaces 110A, 110B. The laser ablation cell 105 can be designed to allow a user / analyst to change between a pair of configurations / modes, for example, by simply replacing the entire particle collection-transport tube interface 110A, 110B. The laser unit 108 of the laser ablation cell 105 can be disposed within the laser ablation cell 105. The selected particle collection-transport tube interface 110A, 110B can be received and attached within the laser ablation cell 105 and disposed directly above the laser unit 108 (e.g., laser diode and associated electronics). In one embodiment, the particle collection-transport tube interfaces 110A, 110B can be received between the laser ablation cell 105 and the laser unit 108. The laser unit 108 can then be configured to ablate (e.g., generate a laser and / or ablation plume) a given sample to be collected by the given particle collection-transport tube interface 110A, 110B. The given particle collection-transport tube interface 110A, 110B can then direct (via a fluid connection) particles from the ablated sample to an analysis unit (not shown). In one embodiment, the interfaces 110A, 110B are complete assemblies that can be switched (e.g., easily removed to install another interface) in minutes. In one embodiment, the first interface 110A has a different distance from the associated sample ablation surface to the collection port compared to the second interface 110B.

[0017] FIG. 1 shows the laser ablation cell 105 with the high-speed / imaging interface 110A attached, and a close-up of the high-speed / imaging interface 110A is shown in FIG. 2. The analysis mode (slower) interface 110B is interchangeable with the interface 110A and is shown in front of and away from the laser ablation cell 105. A close-up of the analysis mode interface 110B is shown in FIG. 3. In one embodiment, one of the given particle collection-transport tube interfaces (e.g., 110A) is optimized to sample the laser plume at close range to enable signal extraction at high speed. In one embodiment, one of the given particle collection-transport tube interfaces (e.g., 110B) is optimized to sample the ablation plume slower to enable slower and more stable signal extraction (e.g., analysis mode applications). It should be understood that other interchangeable interface units can be used based on the situation where the "footprint" and connection points are similar to those of the interfaces 110A, 110B.

[0018] With regard to the second aspect of the disclosure, the hardware system can allow control of both the distance from the sample to the collection port in the chamber and the laser focal plane (e.g., sample ablation plane). The associated software user interface design can automatically change the distance from the sample ablation plane to the collection port when the user selects to switch collection modes (e.g., when switching between interfaces 110A and 110B). The software system allows the user to pattern plan with a larger distance from the sample to the collection port (e.g., as may be indicated by a switch between interfaces 110A and 110B), and automatically moves the sample and laser plane to an ideal high-speed position to the output orifice when in high-speed mode. The software system can easily adjust the distance from the sample / ablation plane to the collection port in high-speed mode by selectively changing the laser focus in tandem and the equidistance to the ablation plane. This second aspect can be useful when used with a user-changeable second volume (e.g., when changing interfaces 110A, 110B).

[0019] The laser ablation system 100 can be controlled by a computing system having a processor configured to execute computer readable program instructions (i.e., control logic) from a non-transitory carrier medium (e.g., a storage medium such as a flash drive, a hard disk drive, a solid-state disk drive, an SD card, an optical disk, etc.). The computing system can be connected to various components of the analysis system by direct connection or via one or more network connections (e.g., a local area network (LAN), a wireless area network (WAN or WLAN)), one or more hub connections (e.g., a USB hub), etc. For example, the computing system can be communicatively coupled (e.g., wired or wirelessly) to the controllable elements of the laser ablation system 100 (e.g., the laser ablation cell 105, the laser unit 108, and / or the particle collection-transport tube interface 110A, 110B). The program instructions, when executed by the processor, can cause the computing system to control the laser ablation system 100. In one implementation, the program instructions form at least a portion of a software program for execution by the processor.

[0020] A processor provides processing functionality to a computing system and may include any number of processors, microcontrollers, or other processing systems, and resident or external memory for storing data and other information accessed or generated by the computing system. A processor is not limited by the material from which it is formed, or the processing mechanisms employed therein, and thus may be implemented via semiconductors and / or transistors (e.g., electronic integrated circuits (ICs), etc.).

[0021] The non-transitory carrier medium is an example of a device-readable storage medium that provides storage capabilities for storing various data related to the operation of the computing system, including, for example, software programs, code segments, or program instructions, or other data that instruct the processor and other elements of the computing system to execute the techniques described herein (e.g., the software systems described above for controlling various operational aspects of the laser ablation system 100). The carrier medium may be integrated with the processor, a standalone memory, or a combination of both. The carrier medium may include, for example, removable and non-removable memory elements such as RAM, ROM, flash (e.g., SD card, mini-SD card, micro-SD card), magnetic, optical, USB memory devices, and the like. In an embodiment of the computing system, the carrier medium may include, for example, a removable ICC (integrated circuit card) memory provided by a SIM (subscriber identity module) card, a USIM (universal subscriber identity module) card, a UICC (universal integrated circuit card), and the like.

[0022] A computing system may include one or more displays for displaying information to a user of the computing system. In embodiments, the displays may include CRT (cathode ray tube) displays, LED (light emitting diode) displays, OLED (organic LED) displays, LCD (liquid crystal diode) displays, TFT (thin film transistor) LCD displays, LEP (light emitting polymer), or PLED (polymer light emitting diode) displays, etc., and are configured to display text and / or graphic information, e.g., a graphical user interface. The displays may be backlit by a backlight so that they can be viewed in dark or other low light environments. The displays may include a touchscreen for receiving input (e.g., data, commands, etc.) from a user. For example, a user may operate the computing system by touching the touchscreen and / or by performing gestures on the touchscreen. In some embodiments, the touchscreen may be a capacitive touchscreen, a resistive touchscreen, an infrared touchscreen, or a combination thereof, etc. A computing system may further include one or more input / output (I / O) devices (e.g., keypads, buttons, wireless input devices, thumbwheel input devices, track stick input devices, etc.) The I / O devices may include one or more audio I / O devices, such as microphones, speakers, etc.

[0023] The computing system may also include a communications module that represents communications functionality, allowing the computing device to transmit / receive data between different devices (e.g., components / peripherals) and / or over one or more networks. The communications module may represent various communications components and functions, including, but not limited to, browsers, transmitters and / or receivers, data ports, software interfaces and drivers, networking interfaces, data processing components, etc.

[0024] The one or more networks represent a variety of different communication paths and network connections that may be used individually or in combination to communicate between components of a given laser ablation-based analysis system. Thus, the one or more networks may represent communication paths implemented using a single network or multiple networks. Additionally, the one or more networks are representative of a variety of different types of networks and connections, including, but not limited to, the Internet, intranets, personal area networks (PANs), local area networks (LANs) (e.g., Ethernet), wide area networks (WANs), satellite networks, cellular networks, mobile data networks, wired and / or wireless connections, and the like. Examples of wireless networks include, but are not limited to, the following: networks configured for communication according to one or more standards of the Institute of Electrical and Electronics Engineers (IEEE), such as the 802.11 or 802.16 (Wi-Max) standards, the Wi-Fi standard promulgated by the Wi-Fi Alliance, the Bluetooth standard promulgated by the Bluetooth Special Interest Group, and the like. Wired communication is also contemplated, such as via Universal Serial Bus (USB), Ethernet, or serial connections.

[0025] The computing system is described as including a user interface that can be stored in a memory (e.g., a carrier medium) and executed by a processor. The user interface represents functionality that controls the display of information and data to a user of the tire computing system via a display. In some implementations, the display is not integrated into the computing system, but instead can be connected externally using a universal serial bus (USB), Ethernet, serial connection, or the like. The user interface can provide functionality that allows a user to interact with one or more applications of the computing system by providing input (e.g., sample ID, desired dilution factor, standard ID, eluent ID / location, fluid addition flow rate, etc.) via a touch screen and / or I / O devices. For example, the user interface can generate an application programming interface (API) to expose functionality to an online dilution control module to configure an application for display by the display or for display in combination with another display. In an embodiment, the API can further expose functionality to configure an in-line dilution control module to enable a user to interact with an application by providing input via a touch screen and / or I / O devices to provide a desired dilution factor for an analysis.

[0026] In an implementation, the user interface may include a browser (e.g., for implementing the functionality of an in-line dilution control module). The browser allows a computing device to display and interact with content, such as web pages in the World Wide Web, web pages provided by a web server in a private network, etc. The browser may be configured in a variety of ways. For example, the browser may be configured as an in-line dilution control module accessed by the user interface. The browser may be a web browser suitable for use by a full-resource device with substantial memory and processor resources (e.g., a smart phone, a personal digital assistant (PDA), etc.).

[0027] In general, any of the functionality described herein may be implemented using software, firmware, hardware (such as fixed logic circuitry), manual processing, or a combination of these implementations. The terms "module" and "functionality" as used herein generally refer to software, firmware, hardware, or a combination thereof. For example, communication between modules in a given laser ablation-based analysis system may be wired, wireless, or some combination thereof. For example, in the case of a software implementation, a module may represent executable instructions that perform a specified task when executed on a processor, such as a processor described herein. The program code may be stored on one or more device-readable storage media, one example of which is a non-transitory carrier medium associated with a computing system.

[0028] Although the inventive subject matter has been described in language specific to structural features and / or methodological acts, it is to be understood that the inventive subject matter is not limited to the particular features or acts described above. Rather, the particular features or acts described above are disclosed by way of example.

Claims

1. 1. A laser ablation system comprising: A laser unit; a laser ablation cell configured to ablate a sample or other material; at least one pair of particle collection-transport tube interfaces configured to collect an ablated sample and direct the ablated sample to an analysis unit, the laser unit being disposed inside the laser ablation cell, a selected particle collection-transport tube interface being disposed directly above the laser unit and received within the laser ablation cell, the at least one pair of particle collection-transport tube interfaces being configured to be interchangeable; Equipped with A number of selected particle collection-transport tube interfaces have different geometries optimized for different applications; Laser ablation systems.

2. each of the particle collection-transport tube interfaces having a similar footprint and connection point layout for interchangeably mounting to the laser ablation cell and onto the laser unit; The laser ablation system of claim 1 .

3. Each of the particle collection-transport tube interfaces is a complete assembly. The laser ablation system of claim 2 .

4. a given one of said particle collection-transport tube interfaces is optimized to sample the laser plume at close range to enable rapid signal extraction; The laser ablation system of claim 1 .

5. a given one of said particle collection-transport tube interfaces is optimized to sample the ablation plume slower, allowing slower and more stable signal extraction; The laser ablation system of claim 1 .

6. the laser ablation cell is configured such that the selected particle collection-transport tube interface allows control of at least one of a distance from a sample ablation surface to a collection port in the laser ablation cell and a position of the sample ablation surface relative to the laser unit by switching between at least one pair of the particle collection-transport tube interfaces; The laser ablation system of claim 1 .

7. the first particle collection-transport tube interface has a different distance from the associated sample ablation surface to the collection port compared to the second particle collection-transport tube interface; The laser ablation system of claim 6 .

8. the laser ablation cell is further configured to automatically change a distance from the sample ablation surface to a collection port when the selected particle collection-transport tube interface is switched between at least a pair of the particle collection-transport tube interfaces. The laser ablation system of claim 6 .

9. When switching between different particle collection-transport tube interfaces, switching of collection modes is facilitated; The laser ablation system of claim 8 .

10. the laser ablation cell is configured such that the selected particle collection-transport tube interface is configured to selectably adjust a distance from a sample ablation surface to a collection port by switching between at least one pair of the particle collection-transport tube interfaces; The laser ablation system of claim 1 .

11. 1. A laser ablation system comprising: A laser unit; a laser ablation cell configured to ablate a sample or other material; at least one pair of particle collection-transport tube interfaces configured to collect an ablated sample and direct the ablated sample to an analysis unit, the laser unit being disposed inside the laser ablation cell, a selected particle collection-transport tube interface being disposed directly above the laser unit and received within the laser ablation cell, the at least one pair of particle collection-transport tube interfaces being configured to be interchangeable; Equipped with Laser ablation systems.

12. the first particle collection-transport tube interface has a similar footprint and connection point layout as the second particle collection-transport tube interface to facilitate interchangeability with each other; The laser ablation system of claim 11 .

13. Each of the particle collection-transport tube interfaces is a complete assembly. The laser ablation system of claim 12 .

14. a given one of said particle collection-transport tube interfaces is optimized to sample the laser plume at close range to enable rapid signal extraction; The laser ablation system of claim 11 .

15. a given one of said particle collection-transport tube interfaces is optimized to sample the ablation plume slower, allowing slower and more stable signal extraction; The laser ablation system of claim 11 .

16. the laser ablation cell is configured such that the selected particle collection-transport tube interface allows control of at least one of a distance from a sample ablation surface to a collection port in the laser ablation cell and a position of the sample ablation surface relative to the laser unit by switching between at least one pair of the particle collection-transport tube interfaces; The laser ablation system of claim 11 .

17. the first particle collection-transport tube interface has a different distance from the associated sample ablation surface to the collection port compared to the second particle collection-transport tube interface; The laser ablation system of claim 16.

18. the laser ablation cell is further configured to automatically change a distance from the sample ablation surface to a collection port when the selected particle collection-transport tube interface is switched between at least a pair of the particle collection-transport tube interfaces. The laser ablation system of claim 16.

19. 1. A method of using a laser ablation system, comprising: providing a laser ablation cell configured to ablate a sample or other material, the laser ablation cell having a laser unit disposed therein, the laser ablation cell receiving a first particle collection-transport tube interface directly above the laser unit; replacing the first particle collection-transport tube interface with a second particle collection-transport tube interface, the first particle collection-transport tube interface being configured to be interchangeable with the second particle collection-transport tube interface; Including, method.

20. a given one of the particle collection-transport tube interfaces is either optimized to sample the laser plume at close range, allowing for fast signal extraction, or optimized to sample the ablation plume slower, allowing for slower, more stable signal extraction; 20. The method of claim 19.

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