Method and apparatus to laser ablation—laser induced breakdown spectroscopy

• US 8,319,964 B2
• Filed: 07/12/2010
• Issued: 11/27/2012
• Est. Priority Date: 07/10/2009
• Status: Active Grant

• Current Assignee: University of Florida Research Foundation, Incorporated (State University System of Florida)
• Original Assignee: University of Florida Research Foundation, Incorporated (State University System of Florida)
• Inventors: Hahn, David Worthington
• Primary Examiner(s): Geisel, Kara E
• Application Number:
  US13/382,825
• Publication Number:
  US 20120099103A1
• Time in Patent Office: 869 Days
• Field of Search: 356/318
• US Class Current: 356/318
• CPC Class Codes: G01N 21/718 Laser microanalysis, i.e. with formation of sample plasma

Abstract

A method and apparatus for analyzing a target material is provided. A first laser beam pulse can be incident on a target material to create an ablation event so as to produce an ablation plume of target material. Such ablation events can include plasma ablation, sub-plasma ablation, and thermal desorption. At least a portion of the ablation plume of target material can then be transported a sufficient distance away from the ablation event that a second laser beam pulse can interact with the at least a portion of the ablation plume of target material to create an analytical plasma such that the analytical plasma is uncoupled from the ablation event. The creation of the analytical plasma results in one or more elements of the at least a portion of the ablation plume of target material undergoing atomic emission, which can be collected and analyzed.

Claims

1. An apparatus for producing atomic emission, comprising:

a target holder, wherein the target holder is adapted to hold a target, wherein the target comprises target material;

at least one laser, wherein the at least one laser is configured to generate a first laser beam pulse, wherein the first laser beam pulse is directed to the target to create an ablation event so as to produce an ablation plume of target material; and

a transport system, wherein the transport system transports at least a portion of the ablation plume of target material a distance d from the ablation event, wherein the at least one laser is configured to generate a second laser beam pulse, wherein the second laser beam pulse is directed to the at least a portion of the ablation plume of target material transported a distance d from the ablation event to produce an analytical plasma, such that one or more elements of the at least a portion of the ablation plume of target material undergo atomic emission, wherein d is sufficiently large that the analytical plasma is uncoupled from the ablation event, wherein the transportation system comprises a flowing carrier gas.

2. The apparatus according to claim 1, wherein the ablation event is a plasma ablation event.

3. The apparatus according to claim 1, wherein the ablation event is a sub-plasma ablation event.

4. The apparatus according to claim 1, wherein the ablation event is selected from the group consisting of:

a thermal desorption ablation event, a laser desorption event, a laser-assisted desorption event, a laser-assisted photochemical desorption event, and a laser-assisted thermal/photochemical desorption event.

5. The apparatus according to claim 1, further comprising:

a collection system, wherein the collection system collects at least a portion of the atomic emission from the one or more elements of the at least a portion of the ablation plume of target material.

6. The apparatus according to claim 5, further comprising:

an analyzer system, wherein the analyzer system analyzes the collected atomic emission to determine information regarding the target material.

7. The apparatus according to claim 1, wherein the at least one laser is a first laser.

8. The apparatus according to claim 7, further comprising a beam splitter, wherein the beam splitter splits a first pulsed laser beam from the first laser so as to produce the first laser beam pulse and the second laser beam pulse.

9. The apparatus according to claim 1, wherein the at least one laser comprises a first laser configured to generate the first laser beam pulse and a second laser configured to generate the second laser beam pulse.

10. The apparatus according to claim 1, wherein d is in the range 0.5 cm to 2 m.

11. The apparatus according to claim 1, wherein d is in the range 1 cm to 10 cm.

12. The apparatus according to claim 1, wherein d is in the range 2 cm to 6 cm.

13. The apparatus according to claim 1, further comprising:

a first focusing lens configured to focus the first laser beam pulse onto the target material to create the ablation event; and

a second focusing lens configured to focus the second laser beam onto the at least a portion of the ablation plume of target material transported a distance d from the ablation event to produce the analytical plasma.

14. The apparatus according to claim 1, wherein a negative pressure gradient causes the carrier gas to flow.

15. The apparatus according to claim 1, wherein a positive pressure gradient causes the carrier gas to flow.

16. The apparatus according to claim 1, wherein the second laser beam pulse produces the analytical plasma a time period after the first laser beam pulse produces the ablation event, wherein the time period is an amount of time to transport the at least a portion of the ablation plume a distance d from the ablation event.

17. The apparatus according to claim 9, further comprising a delay controller, wherein the delay controller is configured to cause the generation of the first laser beam pulse and cause the generation of the second laser beam pulse a delay period after the generation of the first laser beam pulse.

18. The apparatus according to claim 6, wherein the analyzer system comprises a spectrometer.

19. The apparatus according to claim 18, wherein the analyzer system further comprises a detector.

20. The apparatus according to claim 6, wherein the analyzer system comprises a line-filter.

21. The apparatus according to claim 20, wherein the analyzer system further comprises a detector.

22. A method for producing atomic emission, comprising:

directing a first laser beam pulse to a target wherein the target comprises a target material, to produce an ablation event such that an ablation plume of target material is produced;

transporting at least a portion of the ablation plume of target material a distance d away from the ablation event, wherein transporting at least a portion of the ablation plume of target material a distance d away from the ablation event comprises transporting the at least a portion of the ablation plume of target material via a flowing carrier gas; and

directing a second laser beam pulse to the at least a portion of the ablation plume of target material transported a distance d from the ablation event to produce an analytical plasma such that one or more elements of the at least a portion of the ablation plume of target material undergo atomic emission, wherein d is sufficiently large that the analytical plasma is uncoupled from the ablation event.

23. The method according to claim 22, wherein the ablation event is a plasma ablation event.

24. The method according to claim 22, wherein the ablation event is a sub-plasma ablation event.

25. The method according to claim 22, wherein the ablation event is selected from the group consisting of:

a thermal desorption ablation event, a laser desorption event, a laser-assisted desorption event, a laser-assisted photochemical desorption event, and a laser-assisted thermal/photochemical desorption event.

26. The method according to claim 22, further comprising:

collecting the atomic emission from the one or more elements of the at least a portion of the ablation plume of target material.

27. The method according to claim 26, further comprising:

analyzing the collected atomic emission to determine information regarding the target material.

28. The method according to claim 22, wherein the first laser beam pulse and the second laser beam pulse are generated by a first laser.

29. The method according to claim 28, further comprising splitting a first pulsed laser beam from the first laser so as to produce the first laser beam pulse and the second laser beam pulse.

30. The method according to claim 22, wherein the first laser beam pulse is generated by a first laser and the second laser beam pulse is generated by a second laser.

31. The method according to claim 22, wherein d is in the range 0.5 cm to 2 m.

32. The method according to claim 22, wherein d is in the range 1 cm to 10 cm.

33. The method according to claim 22, wherein d is in the range 2 cm to 6 cm.

34. The method according to claim 22, further comprising:

focusing the first laser beam pulse onto the target material via a first focusing lens to create the ablation event; and

focusing the second laser beam onto the at least a portion of the ablation plume of target material transported a distance d from the ablation event via a second focusing lens to produce the analytical plasma.

35. The method according to claim 22, wherein a positive pressure gradient causes the carrier gas to flow.

36. The method according to claim 22, wherein a negative pressure gradient causes the carrier gas to flow.

37. The method according to claim 22, wherein the second laser beam pulse produces the analytical plasma a time period after the first laser beam pulse produces the ablation event, wherein the time period is an amount of time to transport the at least a portion of the ablation plume a distance d from the ablation event.

38. The method according to claim 30, further comprising generating the first laser beam pulse and generating the second laser beam pulse a delay period after generating the first laser beam pulse.

39. The method according to claim 27, wherein analyzing the collected atomic emission comprises analyzing the collected atomic emission via a spectrometer and a detector.

40. The method according to claim 27, wherein analyzing the collected atomic emission comprises analyzing the collected atomic emission via a line-filter and a detector.