Apparatus and method for transporting an aerosol

An apparatus can include ablation chamber body having a transmission window and defining an accommodation region configured to accommodate a target that is movable relative to the transmission window. An aerosol transmission conduit is configured to transport an aerosol produced within the accommodation region to a sample receiving region of an analysis system along a substantially straight transport path.

BACKGROUND

Embodiments of the present invention as exemplarily described herein relate generally to apparatuses for providing aerosol samples and to methods of providing aerosol samples. More particularly, embodiments of the present invention relate to apparatuses and methods capable of transporting aerosol samples to an analysis system with increased efficiency and reduced fractionation.

Analysis systems, such as mass spectrometry (MS) systems, optical emission spectrometry (OES) systems and the like, can be used to analyze the composition of a target material. Often, a sample of the target material is provided to an analysis system in the form of an aerosol. As is known in the art, an aerosol generally characterized as a colloid suspension of solid and possibly liquid particles in a gas. The aerosol is typically produced by an aerosol producing apparatus, entrained by a flowing carrier gas and transported to the analysis system as a sample via an aerosol transport conduit. Conventional aerosol transport conduits can be bent to enable the aerosol producing apparatus to produce multiple samples from different locations of a target material to be analyzed at an analysis system. Thus, aerosol transport paths defined by conventional aerosol transport conduits are non-linear. Due to the non-linearity of conventional aerosol transport paths, the aerosol experiences fractionation as it is transported from the aerosol producing apparatus to the analysis system. As is known in the art, fractionation occurs when particles of different elements, isotopes, size and/or geometry within the aerosol become centrifugally separated as the direction along the aerosol transport path changes. Due to the effects of fractionation, the compositional analysis performed by the analysis system may not accurately correspond to the actual composition of the aerosol produced by the aerosol producing apparatus. Bends within conventional aerosol transport paths can also cause the aerosol transport velocity to vary along the length of the transport path and also vary at different locations within the aerosol transport conduit adjacent to a bend. Such non-uniform transport velocities can cause, among other deleterious effects, agglomeration of particles within the aerosol. As a result, relatively small particles within the aerosol undesirably agglomerate to form larger particles, which tends to decrease the overall transport efficiency of the aerosol along the along the aerosol transport path.

Conventional aerosol transport conduits can also be made flexible to enable the aerosol producing apparatus to produce multiple samples from different locations of a target material to be analyzed at an analysis system. However using flexible aerosol transport conduits can cause the compositional analysis performed by the analysis system to undesirably change depending on the location of the target material from which the aerosol was generated. To reduce undesirable variability of compositional analyses induced by a flexible aerosol transport conduit, the flexible aerosol transport conduit is generally provided as tube roughly a few meters in length. Thus, any movement between opposite ends of the flexible aerosol transport conduit result in a reduced amount of bending between the opposite ends of the flexible aerosol transport conduit. Due to the relatively long length of such aerosol transport conduits, however, the aerosol transport time within the conduit can be undesirably increased. As a result, relatively small particles within the aerosol undesirably agglomerate in a similar manner as described above.

In addition, flexible or bent aerosol transport conduits are conventionally made of a plastic material that can be permeable to atmospheric gases. As a result, atmospheric gases can become undesirably entrained with the aerosol as it is transported through the aerosol transport conduit and cause problems with compositional analysis of the aerosol (e.g., due to formation of interferences and high backgrounds).

SUMMARY

In one embodiment, an apparatus may be provided with a first chamber body having a transmission window configured to transmit a radiation pulse along a transmission direction, the radiation pulse having a fluence sufficient to ablate a portion of a target; a second chamber body adjacent to the first chamber body, wherein the second chamber body is configured to support a target that is ablatable by the radiation pulse and wherein the second chamber body is moveable relative to the transmission window along a translation direction different from the transmission direction, wherein the first chamber body and the second chamber body at least partially define an accommodation region within which the target can be accommodated; and an aerosol transport conduit having a first end and a second end opposite the first end, the aerosol transport conduit defining an aerosol transport region in fluid communication with the accommodation region at the first end and in fluid communication with a region outside the accommodation region at the second end, wherein the aerosol transport conduit is configured to transport an aerosol along a substantially straight transport path extending from the end to the second end, the aerosol including a material ablatable from the target.

In another embodiment, an apparatus may be provided with an ablation chamber including a transmission window and an accommodation region, wherein the transmission window is configured to transmit a radiation pulse along a transmission direction, the radiation pulse having a fluence sufficient to ablate a portion of a target, and wherein the accommodation region is configured to accommodate a target; a target holder disposed within the accommodation region and configured to support the target within the accommodation region, wherein the target holder is configured such that at least one of a position and an orientation of the target within the accommodation region is adjustable; and an aerosol transport conduit having a first end and a second end opposite the first end, the aerosol transport conduit defining an aerosol transport region in fluid communication at the first end and in fluid communication with a region outside the accommodation region at the second end, wherein the aerosol transport conduit is configured to transport an aerosol along a substantially straight transport path extending from the end to the second end, the aerosol including a material ablatable from the target.

In another embodiment of the present invention, a method may include transporting an aerosol from an accommodation region of an ablation chamber body to a sample receiving region of an analysis system along a substantially straight transport path, wherein the analysis system is configured to perform a compositional analysis of the aerosol received within the sample receiving region.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

It will be understood that, although the terms first, second, third, etc., may be used herein to describe various elements, components, regions, sets, etc., these elements, components, regions, sets, should not be limited by these terms. These terms are only used to distinguish one element, component, region, set, etc., from another element, component, region, set, etc. Thus, a first element, component, region, set, etc., discussed below could be termed a second element, component, region, set, etc., without departing from the teachings provided herein.

FIG. 1is a schematic view illustrating an apparatus according to one embodiment.

Referring toFIG. 1, an apparatus, such as apparatus100, includes an ablation chamber102, an ablation beam source104, and an analysis system106. In other embodiments, however, one or both of the ablation beam source104and the analysis system106may be omitted from the apparatus100.

As exemplarily illustrated, the ablation chamber102includes an ablation chamber body108defining an accommodation region108aconfigured to accommodate a target110, a transmission window112configured to transmit a radiation pulse114along a transmission direction, a carrier gas inlet116configured to transmit a carrier gas (e.g., helium, argon, or the like or a combination thereof) from a carrier gas source (not shown) outside the ablation chamber102into the accommodation region108a, and an aerosol transport conduit118coupled to the ablation chamber body108. As will be discussed in greater detail below, the radiation pulse114has a fluence sufficient to ablate a portion of the target110, thereby producing an aerosol plume (also referred to herein simply as an “aerosol,” a “plume”, a “plume of aerosol”, or the like) including material ablated from the target entrained in the carrier gas.

The aerosol transport conduit118includes a first end118aand a second end118band defines an aerosol transport region120extending from the first end118ato the second end118b. In the illustrated embodiment, the aerosol transport conduit118is configured such that the first end118aextends into the accommodation region108aand the second end extends outside the ablation chamber body108. In another embodiment, however, the aerosol transport conduit118can be configured such that the first end118adoes not extend into the accommodation region108a. Likewise, the aerosol transport conduit118can be configured such that the second end118bdoes not extend outside the ablation chamber body108. The aerosol transport region120defines a transport path along which an aerosol is transportable. As exemplarily illustrated, the aerosol transport region120is in fluid communication with the accommodation region108aat the first end118aand is in fluid communication with a region outside accommodation region108a(e.g., a sample receiving region122of the analysis system106) at the second end118b. Constructed as described above, the aerosol transport conduit118is configured to receive a plume of aerosol produced within the accommodation region108aand transport the plume of aerosol within the aerosol transport region120, along the transport path, to the sample receiving region122of the analysis system106. As will be discussed in greater detail below, the analysis system106is configured to perform a compositional analysis on the aerosol transported by the aerosol transport conduit118.

In one embodiment, the transport path defined by the aerosol transport region120is substantially straight such that the aerosol undergoes no fractionation, or no detectable fractionation (i.e., “substantially no fractionation”), as the aerosol is transported from the accommodation region108ato the sample receiving region122(i.e., from the first end118ato the second end118b). In another embodiment, the transport path defined by the aerosol transport region120is substantially straight such that the transport velocity of the aerosol is substantially constant as the aerosol is transported from the accommodation region108ato the sample receiving region122(i.e., from the first end118ato the second end118b).

In one embodiment, the aerosol transport conduit118is substantially rigid such that the transport path can remain substantially straight under normal operating conditions during which the aerosol is transported from the first end118ato the second end118b. Because the aerosol transport conduit118is substantially rigid, it can be formed of a metallic material (e.g., stainless steel, or the like). In one embodiment, the metallic material can be a material that is impermeable to atmospheric gases, or that is less permeable to atmospheric gases than plastic material from which the aforementioned conventional aerosol transport conduits are formed.

The length of the aerosol transport conduit118, measured along the transport path from the first end118to the second end118b, may be less than 5 meter (m). In one embodiment, the length of the aerosol transport conduit118is less than 1 m. In another embodiment, the length of the aerosol transport conduit118is less than 10 centimeters (cm). In yet another embodiment, the length of the aerosol transport conduit118is less than 5 cm. In still another embodiment, the length of the aerosol transport conduit118is less than 3 cm. In such embodiments, however, the length of the aerosol transport conduit118can generally be greater than 1 cm, but may be less than 1 cm. In some embodiments, the length of the aerosol transport conduit118can be selected to prevent or otherwise reduce the degree to which particles within the aerosol undesirably agglomerate as the aerosol is transported from the accommodation region108ato the sample receiving region122(i.e., from the first end118ato the second end118b). Selection of the length of the aerosol transport conduit118can be affected by one or more factors such as the material from which the target110is formed, the energy density of the radiation pulse114, the pulse width of the radiation pulse114, the wavelength of the radiation pulse114, the carrier gas flow rate, or the like.

The aerosol transport conduit118is coupled to the ablation chamber body108so as to be fixedly situated relative to the transmission window112. In one embodiment, the aerosol transport conduit118is fixedly situated relative to the transmission window112such that the aerosol transport conduit118is positionally fixed relative to the transmission window112. In another embodiment, the aerosol transport conduit118is fixedly situated relative to the transmission window112such that the aerosol transport conduit118is orientationally fixed relative to the transmission window112.

The ablation beam source104is configured to direct the radiation pulse114into the accommodation region108a. In another embodiment, the ablation beam source104is also configured to generate the radiation pulse114. Although not illustrated, the ablation beam source104may include a radiation source such as one or more lasers configured to generate a beam of one or more pulses of laser radiation. The one or more lasers may each be, configured to generate laser radiation having a wavelength greater than about 157 nm and less than about 1064 nm. For example, the one or more lasers may each be configured to generate a wavelength selected from the group consisting of 266 nm, 213 nm, 193 nm, or the like. Each of the one or more lasers may be configured to generate laser pulses having pulse width between about 1.0 picoseconds to about 25 nanoseconds. The ablation beam source104may also include laser optics configured to focus the laser radiation generated by one or more of the lasers.

As mentioned above, the analysis system106is configured to perform a compositional analysis on the aerosol transported by the aerosol transport conduit118. The analysis system106may be provided as any suitable system such as an MS system (e.g., a noble gas MS system, a stable isotope MS system, etc.), an OES system, or the like, or a combination thereof. Generally, however, the analysis system106includes a sample preparation module configured to excite (e.g., ionize, atomize, illuminate, heat, etc.) one or more components of the aerosol received within the sample, receiving region122and a detector module configured to detect one or more characteristics (e.g., electromagnetic emission or absorption, particle mass, ionic mass, or the like or a combination thereof) of the excited component(s) of the aerosol received in the sample receiving region122. Techniques for exciting one or more components of the aerosol received within the sample receiving region122include plasma generation (e.g., via an inductively coupled plasma (ICP) torch), spark ionization, thermal ionization, atmospheric pressure chemical ionization, fast atom bombardment, glow discharge, and the like or a combination thereof. In one embodiment, the analysis system106may further include a sort module configured to sort the excited component(s) of the aerosol received in the sample receiving region122based on one or more of the aforementioned characteristics before the detector module detects a characteristic.

In one embodiment, the apparatus100further includes a shield124disposed between the ablation chamber102and the ablation beam source104. The shield124may be formed of a material that is at least partially transparent to the radiation pulse114. In the illustrated embodiment, the shield124abuts the ablation chamber body108and covers the transmission window112to prevent debris (e.g., dust, water vapor, atmospheric gases such as air, and the like) from undesirably entering into the accommodation region108aduring ablation of the target110. The ablation beam source106is generally disposed in close proximity to the shield124(as illustrated), and may abut the shield124, to reduce or eliminate any deleterious interference of transmission of the radiation pulse into the accommodation region108acaused by debris outside the ablation chamber body108. In one embodiment, the shield124may be coupled to one or both of the ablation beam source104and the ablation chamber body108.

In another embodiment, the apparatus100optionally includes a target holder126disposed within the accommodation region108a. The target holder126may be configured to hold or support the target110within the accommodation region to ensure that a surface110aof the target110is desirably situated within the accommodation region108awhen the radiation pulse114is transmitted into the accommodation region108a. In one embodiment, the target holder126may be configured such that at least one of a position and an orientation of the target110within the accommodation region108is adjustable to ensure that the portion of the surface110ato be ablated by the radiation pulse114is desirably situated within the accommodation region108a, even if other portions of the surface110aare not desirably situated within the accommodation region108a.

FIG. 2is a cross-sectional view schematically illustrating one embodiment of an ablation chamber of the apparatus shown inFIG. 1.FIG. 3is a cross-sectional view schematically illustrating an embodiment in which the second chamber body of the ablation chamber shown inFIG. 2is moveable relative to the first chamber body.

Referring toFIG. 2, the ablation chamber body108shown inFIG. 1may, according to one embodiment, include a first chamber body202and a second chamber body204adjacent to the first chamber body202. As exemplarily shown, the first chamber body202and the second chamber body204define the accommodation region108a. However, the ablation chamber102may include other components that at least partially define the accommodation region108a. Thus, the first chamber body202and the second chamber body204may at least partially define the accommodation region108a. Although not shown, one or more biasing members (e.g., springs) may be provided to uniformly press the one chamber body (e.g., the second chamber body204) against the other chamber body (e.g., the first chamber body202).

The transmission window112is defined within the first chamber body202and the second chamber body204is moveable relative to the transmission window112(e.g., as indicated by arrow302shown inFIG. 3). For example, the second chamber body204may be placed on movable stage206(e.g., supported by a relatively stationary base208) that is configured to move the second chamber body204along one or more translation directions different from the aforementioned transmission direction. The base208may, in turn, be provided on a sufficiently stable mounting surface (not shown) such as a table, a floor, or the like. A frame (not shown) supported by, for example, the aforementioned mounting surface, may be coupled to the first chamber body202to support the first chamber body202as the second chamber body204is moved by the movable stage206. In one embodiment in which the shield124is coupled to one or both of the ablation beam source104and the ablation chamber body108, the frame may be similarly coupled to one or more of the shield124and the ablation beam source104in addition to (or instead of) the first chamber body202.

In the illustrated embodiment, the aerosol transport conduit118is extends through the first chamber body202such that the first end118aextends into the accommodation region108aand the second end extends outside the ablation chamber body108. In other embodiments, however, the one or both of the first end118aand the second end118bare disposed at within the first chamber body202or at an edge of the first chamber body202. Moreover, aerosol transport conduit118may be provided as a bore or one, or more channels (not shown) formed in the first chamber body202.

The aerosol transport conduit118can be coupled to the first chamber body202in any suitable manner that results in the aerosol transport conduit118being fixedly situated relative to the transmission window112as described above. For example, the aerosol transport conduit118may be inserted into a bore (not shown) or one or more channels (not shown) formed in the first chamber body202and secured therein by an adhesive, one or more welds, or other locking members (e.g., screws, clamps, or the like or a combination thereof) or any biasing member structured to bias the aerosol transport conduit118against the first chamber body202. In one embodiment, the aerosol transport conduit118is coupled to the first chamber body202such the aerosol transport conduit118is fixedly situated relative to the transmission window112as the second chamber body204moves relative to the transmission window112.

In one embodiment, the ablation chamber102may include an aerosol collector210defining a collection region210a. In one embodiment, the aerosol collector210is coupled to the first chamber body202by a collector support member212(e.g., a pin, screw, clamp, etc.). The collector support member212can be configured to align the aerosol collector210relative to the transmission window112to ensure that the radiation pulse114is transmitted into the accommodation region108athrough the collection region210awith little or no interference by the aerosol collector210. In one embodiment, collector support member212may be configured such that at least one of a position and an orientation of the aerosol collector210is adjustable relative to the transmission window112.

At least a portion of the aerosol collector210can be disposed within the accommodation region108asuch that the collection region210ais in fluid communication with the accommodation region108a. In one embodiment, the aerosol collector210is disposed such that a small gap is formed between the aerosol collector210and the surface110aof the target110. The height of the gap should be selected to ensure that at least a portion of the aerosol plume produced upon ablation of the surface110aby the radiation pulse114is formed within the collection region110a. The height of the gap can also be selected so as to ensure that carrier gas flowing into the accommodation region108aand over the surface110aof the target110can flow into the collection region210a.

At least a portion of the aerosol collector210can be disposed within the accommodation region108asuch that the collection region210ais in fluid communication with the aerosol transport region120. In the illustrated embodiment, the aerosol collector210includes a bore (shown, but not labeled) located between the bottom and the top of the aerosol collector210. The bore may be in fluid communication with the collection region210aand the first end118aof the aerosol transport conduit118can be inserted into or otherwise coupled to the bore. In other embodiments, however, the first end may be disposed above the top of the aerosol collector210.

By providing the aerosol collector210as exemplarily described above, the volume of the aerosol plume produced upon ablation of the surface110aby the radiation pulse114can be made relatively small, thereby improving transport of the aerosol through the aerosol transport region120to the sample receiving region122of the analysis system106. While the aerosol collector210has been described above as a separate piece from the first chamber body202, the aerosol collector210and the first chamber body202can also be formed as a single, monolithic structure.

FIGS. 4 and 5are cross-sectional views schematically illustrating barriers configured to prevent debris from entering into the ablation chamber shown inFIG. 2, according to some embodiments.

As discussed above, the second chamber body204is movable relative to the first chamber body202along one or more translation directions. In some embodiments, a barrier can be provided to prevent debris (e.g., dust, water vapor, atmospheric gases such as air, and the like) from undesirably entering into the accommodation region108awhen the second chamber body204is moved.

Referring toFIG. 4, a barrier according to one embodiment can be provided as a seal, such as seal402, disposed between opposing surfaces of the first chamber body202and the second chamber body204. The seal402can be provided as any type of seal capable of preventing debris from entering into the accommodation region108awhile permitting the second chamber body204from moving relative to the first chamber body202without generating an undesirable amount of friction. In one embodiment, the seal402is provided as a face seal (e.g., an O-ring, C-ring, U-ring, etc.). The face seal may optionally be spring loaded. An exterior surface of the face seal may be coated a relatively inert, low-friction material such as polytetrafluoroethylene (PTFE).

Referring toFIG. 5, a barrier according to another embodiment can be provided as a gas curtain, such as gas curtain502, surrounding a perimeter of the first chamber body202and the second chamber body204. The gas curtain502may include a curtain of gas (e.g., helium, argon, etc.) flowing (e.g., along the direction indicated by arrow504) with at a sufficient flow rate to prevent debris from undesirably entering into the accommodation region108a.

Although only two examples of barriers have been illustrated, it will be appreciated that other barriers may be provided. For example, a barrier could be provided as a bellows-type structure including a flexible sheet material (e.g., a fabric) coupled to the first chamber body202and the second chamber body204that changes shape as the second chamber body204moves relative to the first chamber body202, but that maintains a suitable barrier between the accommodation region108and the environment outside the ablation chamber body108. It will also be appreciated that more than one type of barrier can be simultaneously used to help prevent debris from undesirably entering into the accommodation region108.

Having described the apparatus above, it will be appreciated that embodiments of the present invention may be implemented and practiced in many different forms. For example, in one embodiment, an apparatus may include an aerosol transmission conduit configured to transport an aerosol from an accommodation region of an ablation chamber body to a sample receiving region of an analysis system along a substantially straight transport path, wherein the analysis system is configured to perform a compositional analysis of the aerosol received within the sample receiving region.

In another embodiment of the present invention, an apparatus may include a first portion of an ablation chamber body and an aerosol transmission conduit, wherein the first portion of an ablation chamber body and the aerosol transmission conduit are configured to transport an aerosol from an accommodation region of an ablation chamber body to a sample receiving region of an analysis system along a substantially straight transport path while another portion of the ablation chamber body moves relative to the first portion of the ablation chamber body, wherein the analysis system is configured to perform a compositional analysis of the aerosol received within the sample receiving region.

In another embodiment of the present invention, a method may include transporting an aerosol from an accommodation region of an ablation chamber body to a sample receiving region of an analysis system along a substantially straight transport path, wherein the analysis system is configured to perform a compositional analysis of the aerosol received within the sample receiving region. In such an embodiment, the method may optionally include ablating a target within the accommodation region to produce the aerosol, performing the compositional analysis on the aerosol at the analysis system, or a combination thereof.

The foregoing is illustrative of embodiments of the invention and is not to be construed as limiting thereof. Although a few example embodiments of the invention have been described, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without materially departing from the novel teachings and advantages of the invention. Accordingly, all such modifications are intended to be included within the scope of the invention as defined in the claims. Therefore, it is to be understood that the foregoing is illustrative of the invention and is not to be construed as limited to the specific example embodiments of the invention disclosed, and that modifications to the disclosed example embodiments, as well as other embodiments, are intended to be included within the scope of the appended claims. The invention is defined by the following claims, with equivalents of the claims to be included therein.