Spectroscopic systems for the analysis of small and very small quantities of substance

• US 6,108,083 A
• Filed: 08/11/1997
• Issued: 08/22/2000
• Est. Priority Date: 08/13/1992
• Status: Expired due to Fees

• Current Assignee: Agilent Technologies, Inc.
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Machler, Meinrad
• Primary Examiner(s): EVANS, FANNIE L
• Application Number:
  US08/907,903
• Time in Patent Office: 1,107 Days
• Field of Search: 356/301, 356/246, 356/440, 356/328, 385/125
• US Class Current: 356/328
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0216 using light concentrators or collectors or condensers
• CPC Class Codes: G01N 21/0303 Optical path conditioning in cuvettes, e.g. windows; adapted optical elements or systems; path modifying or adjustment G01N21/031 - G01N21/15 take precedence
• CPC Class Codes: G01N 2201/0813 Arrangement of collimator tubes, glass or empty
• CPC Class Codes: G01N 2201/084 Fibres for remote transmission

Abstract

A spectroscopic system for the analysis of small quantities of substances makes use for the purposes of energy transfer of cone-shaped aperture changers which are arranged in the object zone between the light source and the sample and, during absorption measurements, also between the sample and the inlet slot of a spectrometer. A microcell system is provided in the object space. The microcell system comprises a cylindrical cell tube with a hollow core for receiving a sample liquid. The cell tube and the sample liquid being adjustable with respect to the refractive index such that they act as a step waveguide for radiation, the sample liquid forming the core and the wall of the cell tube forming the sheath of the step waveguide.

Claims

1. Microcell system for absorption photometry, comprising a cylindrical cell tube with a hollow core for receiving a sample liquid which is traversed at least in a longitudinal section of the hollow core by radiation whose absorption is subsequently measured, the cell tube and the sample liquid being adjustable with respect to the refractive index such that they act as a step waveguide for radiation, said sample liquid forming the core and said wall of the cell tube forming the sheath of said step waveguide, characterized by an axial coupling of radiation at the cell, wherein an outer wall of the cell tube is reflective to reflect radiation at least several times through the sample.

2. Microcell system according to claim 1, characterized in that radiation is supplied to the step waveguide formed by the cell tube and the sample liquid with an aperture angle corresponding to the maximum aperture of the step waveguide.

3. Microcell system according to claims 1, characterized in that the cell tube is made of an isotropic material which is non-absorbing in the spectral range concerned.

4. Microcell system according to claims 1, characterized in that the cell tube is a circular cylindrical micro-capillary having an inside diameter of less than 0.5 mm, and an outside diameter of less than 1.0 mm.

5. Microcell system according to claims 4, wherein said inside diameter is less than 0.25 mm, and said out side diameter is less than 0.35 mm.

6. Microcell system according to claim 4, wherein said inside diameter is less than 0.15 mm, and said outside diameter is less than 0.20 mm.

7. Microcell system according to claims 1, characterized by a low-reflection transition between the sample liquid and the material of the cell tube.

8. Microcell system according to claims 1, characterized in that for a range of radiation wavelength of from about 200 to 1000 nm a cell tube made of quartz is used.

9. The microcell system according to claim 1 in a spectroscopic system.

10. The microcell system according to claim 1 in absorption spectrometry.

11. The microcell system according to claim 1 in high performance liquid chromatography.

13. Microcell system according to claims 1, characterized by an oblique coupling and/or oblique decoupling of radiation at the cell.

14. Microcell system according to claims 1, characterized by an oblique decoupling of radiation at the cell.

15. Microcell system according to claim 13, characterized in that said coupling and/or decoupling of radiation is effected by means of a cone-shaped body comprising a groove or flattening on the cone sheath, said cell tube being supported in the groove by interposition of a non-absorbing means such that, when coupling of radiation is effected, the tip of the cone-shaped body points in the direction of passage of radiation and, when radiation is decoupled, the tip of the cone-shaped body points in the direction opposite the passage of radiation.

16. Microcell system according to claim 15, characterized in that the cone-shaped body has a circular cylindrical shape.

17. Microcell system according to claim 16, characterized in that the angle included by the longitudinal axis of the cone and the cone sheath is no greater than a quarter of the maximum aperture angle of the step waveguide.

18. Microcell system according to claim 16, characterized in that, when a cone-shaped body and a cell tube made of quartz are used, the angle included by the longitudinal axis of the cone and the cone sheath is about 15°

to 22.5°

.

19. Microcell system according to claim 18, wherein the angle is about 22°

to 22.5°

.

23. Microcell system according to claim 15, characterized in that two cone-shaped bodies are spaced apart such that the grooves thereof are in alignment with each other and face upwards, and that the cell tube is provided in the grooves.

24. Microcell system according to claim 23, characterized in that at least one of the cone-shaped bodies is displaceable along the cell tube for adjusting the optical path length of the cell tube to be subjected to absorption measurement.

12. Microcell system for absorption photometry, comprising a cylindrical cell tube with a hollow core for receiving a sample liquid which is traversed at least in a longitudinal section of the hollow core by radiation whose absorption is subsequently measured, the cell tube and the sample liquid being adjustable with respect to the refractive index such that they act as a step waveguide for radiation, said sample liquid forming the core and said wall of the cell tube forming the sheath of said step waveguide, characterized in that the cell system is connected to a light source by means of an aperture changer comprising a member with a light entry port and a light exit port, the larger of said ports facing the cell tube.

20. Microcell system according to claim 12, characterized in that the cone-shaped body and an associated aperture changer are preferably designed as a one-piece double cone.

21. Microcell system according to claim 20, characterized in that between the aperture changer and the cone-shaped body there is provided a cylindrical part coupling the exit area of the aperture changer to the entrance area of the cone-shaped body.

22. Microcell system according to claim 21, characterized in that said at least one double cone is preferably mounted via point-shaped contact surfaces in the cylindrical part.

25. Microcell system according to claim 20, characterized in that the double cone is displaceably mounted.

26. Microcell system for absorption photometry, comprising a cylindrical cell tube with a hollow core for receiving a sample liquid which is traversed at least in a longitudinal section of the hollow core by radiation whose absorption is subsequently measured, the cell tube and the sample liquid being adjustable with respect to the refractive index such that they act as a step waveguide for radiation, said sample liquid forming the core and said wall of the cell tube forming the sheath of said step waveguide, characterized by an axial coupling of radiation at the cell, wherein the cell system is connected to a light source by means of an aperture changer comprising a member with a light entry port and a light exit port, the larger of said ports facing the cell tube.

27. Microcell system according to claim 26, characterized in that the aperture changer is made of the same material as the cell tube.

28. Microcell system according to claim 27, wherein the light entry port and the light exit port of the aperture changer are cross-sectional openings perpendicular to the optical axis.

29. Microcell system according to claim 26, wherein the light used is a point source of light imaged by an aspherical mirror, and further including a light guide arranged to transmit light from said aspherical mirror to said entry port of said inlet aperture port, characterized in that at least a portion of the light guide is arranged opposite the smaller cross-sectional opening of the aperture changer, the cross-section of said light-guide portion in the area of contact with the aperture changer corresponding to said smaller cross-sectional opening.

30. Microcell system according to claim 29, characterized in that the light guide, at least between the end portions thereof, is formed as a preferably flexible light wire.

31. Microcell system according to claim 29, characterized in that at least one light-conducting fiber of the light guide is made of the same material as the cell tube.

32. Microcell system according to claim 26 wherein the aperture changer comprises a cone, the outlet aperture of the cone being larger than the inlet aperture thereof.

33. Microcell system according to claim 32, characterized in that, when the material used for the cell tube, the cone, and the aperture changer is quartz, the angle included by the cone sheath of the aperture changer relative to the central axis thereof is about 13°

and the angle included by the cone sheath of the cone-shaped body relative to the central axis thereof is about 20°

to 22.5°

.

34. Spectroscopic system, wherein at least one sample is illuminated by light emitted from a light source and the light from the sample is concentrated on the entrance slit of at least one spectrometer, characterized in that a microcell system is provided in an object space between the entrance slit of the spectrometer and the light source or its image, the microcell system comprising a cylindrical cell tube with a hollow core for receiving a sample liquid which is traversed at least in a longitudinal section of the hollow core by radiation whose absorption is subsequently measured, the cell tube and the sample liquid being adjustable with respect to the refractive index such that they act as a step waveguide for radiation, said sample liquid forming the core and said wall of the cell tube forming the sheath of said step waveguide, wherein an outer wall of the cell tube is reflective to reflect radiation at least several times through the sample liquid.

35. Spectroscopic system according to claim 34, characterized in that the light source used is a point source of light which is imaged by means of an aspherical mirror, on the entry port of an aperture changer arranged between the light source and the object.

36. Spectroscopic system according to claim 34, characterized in that the spectrometer comprises a diffraction grating and a receiving unit.

37. Spectroscopic system according to claim 36, characterized in that the diffraction grating is a holographic concave grating and the receiving unit is a line of photodiodes.

38. Spectroscopic system according to claim 37, characterized in that the mirror and the concave grating have the same aperture.

39. Spectroscopic system according to claim 34, characterized in that the microcell system is arranged in a reaction chamber in which the sample is subjected to physical influences.

40. Spectroscopic system according to claim 34, characterized in that the microcell system includes microcells defined by activated capillary sections.

41. Spectroscopic system according to claim 34, characterized in that the microcell system serves as radiation source for a secondary radiation stimulated by primary radiation.

42. Microcell system for absorption photometry, comprising a cylindrical cell tube with a hollow core for receiving a sample liquid which is traversed at least in a longitudinal section of the hollow core by radiation whose absorption is subsequently measured, the cell tube and the sample liquid being adjustable with respect to the refractive index such that they act as a step waveguide for radiation, said sample liquid forming the core and said wall of the cell tube forming the sheath of said step waveguide, characterized in that a metal layer is applied on the outer surface of the cell tube at least in partial sections thereof.

43. Microcell system for absorption photometry, comprising a cylindrical cell tube with a hollow core for receiving a sample liquid which is traversed at least in a longitudinal section of the hollow core by radiation whose absorption is subsequently measured, the cell tube and the sample liquid being adjustable with respect to the refractive index such that they act as a step waveguide for radiation, said sample liquid forming the core and said wall of the cell tube forming the sheath of said step waveguide, characterized in that said cell is a flow-through cell, and on both ends of the cell tube an annular attachment piece is mounted which comprises inlet and outlet ports which open into inlet and outlet bores of the cell tube, and that a metal layer is applied between the attachment piece and the outer surface of the cell tube.

44. Microcell system for absorption photometry, comprising a cylindrical cell tube with a hollow core for receiving a sample liquid which is traversed at least in a longitudinal section of the hollow core by radiation whose absorption is subsequently measured, the cell tube and the sample liquid being adjustable with respect to the refractive index such that they act as a step waveguide for radiation, said sample liquid forming the core and said wall of the cell tube forming the sheath of said step waveguide, characterized in that the cell system is connected to a measuring device by means of an aperture changer comprising a member with a light entry port and a light exit port, the larger of said ports facing the cell tube.

45. Spectroscopic system, wherein at least one sample is illuminated by light emitted from a light source and the light from the sample is concentrated on the entrance slit of at least one spectrometer, characterized in that a microcell system is provided in an object space between the entrance slit of the spectrometer and the light source or its image, the microcell system comprising a cylindrical cell tube with a hollow core for receiving a sample liquid which is traversed at least in a longitudinal section of the hollow core by radiation whose absorption is subsequently measured, the cell tube and the sample liquid being adjustable with respect to the refractive index such that they act as a step wave for radiation, said sample liquid forming the core, and said wall of the cell tube forming the sheath of said step waveguide, wherein a metal layer is applied on the outer surface of the cell tube at least in partial sections thereof.

46. Spectroscopic system, wherein at least one sample is illuminated by light emitted from a light source and the light from the sample is concentrated on the entrance slit of at least one spectrometer, characterized in that a microcell system is provided in an object space between the entrance slit of the spectrometer and the light source or its image, the microcell system comprising a cylindrical cell tube with a hollow core for receiving a sample liquid which is traversed at least in a longitudinal section of the hollow core by radiation whose absorption is subsequently measured, the cell tube and the sample liquid being adjustable with respect to the refractive index such that they act as a step wave for radiation, said sample liquid forming the core, and said wall of the cell tube forming the sheath of said step waveguide, the material of the cell tube is selected such that at the outside thereof there is total reflection with respect to a gas surrounding the cell.

47. Spectroscopic system, wherein at least one sample is illuminated by light emitted from a light source and the light from the sample is concentrated on the entrance slit of at least one spectrometer, characterized in that a microcell system is provided in an object space between the entrance slit of the spectrometer and the light source or its image, the microcell system comprising a cylindrical cell tube with a hollow core for receiving a sample liquid which is traversed at least in a longitudinal section of the hollow core by radiation whose absorption is subsequently measured, the cell tube and the sample liquid being adjustable with respect to the refractive index such that they act as a step wave for radiation, said sample liquid forming the core, and said wall of the cell tube forming the sheath of said step waveguide, wherein on both ends of the cell tube an annular attachment piece is mounted which comprises inlet and outlet ports which open into inlet and outlet bores of the cell tube, and a metal layer is applied between the attachment piece and the outer surface of the cell tube.

48. Spectroscopic system, wherein at least one sample is illuminated by light emitted from a light source and the light from the sample is concentrated on the entrance slit of at least one spectrometer, characterized in that a microcell system is provided in an object space between the entrance slit of the spectrometer and the light source or its image, the microcell system comprising a cylindrical cell tube with a hollow core for receiving a sample liquid which is traversed at least in a longitudinal section of the hollow core by radiation whose absorption is subsequently measured, the cell tube and the sample liquid being adjustable with respect to the refractive index such that they act as a step wave for radiation, said sample liquid forming the core, and said wall of the cell tube forming the sheath of said step waveguide, wherein there is an oblique coupling of radiation at the cell.

49. Spectroscopic system, wherein at least one sample is illuminated by light emitted from a light source and the light from the sample is concentrated on the entrance slit of at least one spectrometer, characterized in that a microcell system is provided in an object space between the entrance slit of the spectrometer and the light source or its image, the microcell system comprising a cylindrical cell tube with a hollow core for receiving a sample liquid which is traversed at least in a longitudinal section of the hollow core by radiation whose absorption is subsequently measured, the cell tube and the sample liquid being adjustable with respect to the refractive index such that they act as a step wave for radiation, said sample liquid forming the core, and said wall of the cell tube forming the sheath of said step waveguide, wherein there is an oblique decoupling of radiation at the cell.

50. Spectroscopic system, wherein at least one sample is illuminated by light emitted from a light source and the light from the sample is concentrated on the entrance slit of at least one spectrometer, characterized in that a microcell system is provided in an object space between the entrance slit of the spectrometer and the light source or its image, the microcell system comprising a cylindrical cell tube with a hollow core for receiving a sample liquid which is traversed at least in a longitudinal section of the hollow core by radiation whose absorption is subsequently measured, the cell tube and the sample liquid being adjustable with respect to the refractive index such that they act as a step wave for radiation, said sample liquid forming the core, and said wall of the cell tube forming the sheath of said step waveguide, wherein the cell system is connected to a light source by means of an aperture changer comprising a member with a light entry port and a light exit port, the larger of said ports facing the cell tube.

51. Spectroscopic system, wherein at least one sample is illuminated by light emitted from a light source and the light from the sample is concentrated on the entrance slit of at least one spectrometer, characterized in that a microcell system is provided in an object space between the entrance slit of the spectrometer and the light source or its image, the microcell system comprising a cylindrical cell tube with a hollow core for receiving a sample liquid which is traversed at least in a longitudinal section of the hollow core by radiation whose absorption is subsequently measured, the cell tube and the sample liquid being adjustable with respect to the refractive index such that they act as a step wave for radiation, said sample liquid forming the core, and said wall of the cell tube forming the sheath of said step waveguide, wherein the cell system is connected to a measuring device by means of an aperture changer comprising a member with a light entry port and a light exit port, the larger of said ports facing the cell tube.

52. Microcell system for absorption photometry, comprising a cylindrical cell tube with a hollow core for receiving a sample liquid which is traversed at least in a longitudinal section of the hollow core by radiation whose absorption is subsequently measured, the cell tube and the sample liquid being adjustable with respect to the refractive index such that they act as a step waveguide for radiation, said sample liquid forming the core and said wall of the cell tube forming the sheath of said step waveguide, characterized by an axial coupling of radiation at the cell, wherein a metal layer is applied on the outer surface of the cell tube at least in partial sections thereof.

53. Microcell system for absorption photometry, comprising a cylindrical cell tube with a hollow core for receiving a sample liquid which is traversed at least in a longitudinal section of the hollow core by radiation whose absorption is subsequently measured, the cell tube and the sample liquid being adjustable with respect to the refractive index such that they act as a step waveguide for radiation, said sample liquid forming the core and said wall of the cell tube forming the sheath of said step waveguide, characterized by an axial coupling of radiation at the cell, wherein the material of the cell tube is selected such that at the outside thereof there is a total reflection with respect to a gas surrounding the cell.

54. Microcell system for absorption photometry, comprising a cylindrical cell tube with a hollow core for receiving a sample liquid which is traversed at least in a longitudinal section of the hollow core by radiation whose absorption is subsequently measured, the cell tube and the sample liquid being adjustable with respect to the refractive index such that they act as a step waveguide for radiation, said sample liquid forming the core and said wall of the cell tube forming the sheath of said step waveguide, characterized by an axial coupling of radiation at the cell, wherein said cell is a flow-through cell and wherein on both ends of the cell tube an annular attachment piece is mounted which comprises inlet and outlet ports which open into inlet and outlet bores of the cell tube, and that a metal layer is applied between the attachment piece and the outer surface of the cell tube.

55. Microcell system for absorption photometry, comprising a cylindrical cell tube with a hollow core for receiving a sample liquid which is traversed at least in a longitudinal section of the hollow core by radiation whose absorption is subsequently measured, the cell tube and the sample liquid being adjustable with respect to the refractive index such that they act as a step waveguide for radiation, said sample liquid forming the core and said wall of the cell tube forming the sheath of said step waveguide, characterized by an axial coupling of radiation at the cell, wherein the cell system is connected to a measuring device by means of an aperture changer comprising a member with a light entry port and a light exit port, the larger of said ports facing the cell tube.

56. Microcell system for absorption photometry, comprising a cylindrical cell tube with a hollow core for receiving a sample liquid which is traversed at least in a longitudinal section of the hollow core by radiation whose absorption is subsequently measured, the cell tube and the sample liquid being adjustable with respect to the refractive index such that they act as a step waveguide for radiation, said sample liquid forming the core and said wall of the cell tube forming the sheath of said step waveguide, characterized by an axial decoupling of radiation at the cell, wherein an outer wall of the cell tube is reflective to reflect radiation at least several times through the sample.

57. Microcell system for absorption photometry, comprising a cylindrical cell tube with a hollow core for receiving a sample liquid which is traversed at least in a longitudinal section of the hollow core by radiation whose absorption is subsequently measured, the cell tube and the sample liquid being adjustable with respect to the refractive index such that they act as a step waveguide for radiation, said sample liquid forming the core and said wall of the cell tube forming the sheath of said step waveguide, characterized by an axial decoupling of radiation at the cell, wherein a metal layer is applied on the outer surface of the cell tube at least in partial sections thereof.

58. Microcell system for absorption photometry, comprising a cylindrical cell tube with a hollow core for receiving a sample liquid which is traversed at least in a longitudinal section of the hollow core by radiation whose absorption is subsequently measured, the cell tube and the sample liquid being adjustable with respect to the refractive index such that they act as a step waveguide for radiation, said sample liquid forming the core and said wall of the cell tube forming the sheath of said step waveguide, characterized by an axial decoupling of radiation at the cell, wherein the material of the cell tube is selected such that at the outside thereof there is total reflection with respect to a gas surrounding the cell.

59. Microcell system for absorption photometry, comprising a cylindrical cell tube with a hollow core for receiving a sample liquid which is traversed at least in a longitudinal section of the hollow core by radiation whose absorption is subsequently measured, the cell tube and the sample liquid being adjustable with respect to the refractive index such that they act as a step waveguide for radiation, said sample liquid forming the core and said wall of the cell tube forming the sheath of said step waveguide, characterized by an axial decoupling of radiation at the cell, wherein said cell is a flow-through cell and wherein on both ends of the cell tube an annular attachment piece is mounted which comprises inlet and outlet ports which open into inlet and outlet bores of the cell tube, and that a metal layer is applied between the attachment piece and the outer surface of the cell tube.

60. Microcell system for absorption photometry, comprising a cylindrical cell tube with a hollow core for receiving a sample liquid which is traversed at least in a longitudinal section of the hollow core by radiation whose absorption is subsequently measured, the cell tube and the sample liquid being adjustable with respect to the refractive index such that they act as a step waveguide for radiation, said sample liquid forming the core and said wall of the cell tube forming the sheath of said step waveguide, characterized by an axial decoupling of radiation at the cell, wherein the cell system is connected to a light source by means of an aperture changer comprising a member with a light entry port and a light exit port, the larger of said ports facing the cell tube.

61. Microcell system for absorption photometry, comprising a cylindrical cell tube with a hollow core for receiving a sample liquid which is traversed at least in a longitudinal section of the hollow core by radiation whose absorption is subsequently measured, the cell tube and the sample liquid being adjustable with respect to the refractive index such that they act as a step waveguide for radiation, said sample liquid forming the core and said wall of the cell tube forming the sheath of said step waveguide, characterized by an axial decoupling of radiation at the cell, wherein the cell system is connected to a measuring device by means of an aperture changer comprising a member with a light entry port and a light exit port, the larger of said ports facing the cell tube.