Apparatus and method for real-time spectral deconvolution of chemical mixtures

• US 5,567,625 A
• Filed: 10/19/1994
• Issued: 10/22/1996
• Est. Priority Date: 10/19/1994
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Lew, John S., Kurtzberg, Jerome M.
• Primary Examiner(s): ALEXANDER, LYLE
• Application Number:
  US08/326,101
• Time in Patent Office: 734 Days
• Field of Search: 436/164, 436/805, 422/68.1, 422/77, 422/82.05, 422/82.11
• US Class Current: 436/164
• CPC Class Codes: G01N 21/31 Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry G01N21/72 takes precedence
• CPC Class Codes: Y10S 436/805 Optical property

Abstract

An apparatus and method are described for determining the relative concentrations of the constituent chemical components of a chemical combination. The spectral response of the composite sample, measured at a number of wavelengths λ_i, is represented by a vector C. The relative concentration of the jth constituent is X_j, and the relative concentrations of each of the chemical constituents are represented by the vector X. The vector X can be determined from the vector C by the following matrix equation:

X=(A.sup.T A).sup.-1 A.sup.T C

wherein the matrix A has elements A_ij, which is the spectral response of the jth component at wavelength λ_i. Since the matrix A is a predetermined set of numbers, the elements of vector X are readily determined from the above equation. Such a determination is rapid; a profile of each of the constituents X_j in the sample is readily and rapidly determined.

Claims

1. An apparatus for determining the concentrations X_j of N component chemical constituents, wherein j=1 to N, in a chemical combination using predetermined relative constituent spectral intensities A_ij of said N component chemical constituents, wherein i=1 to M, wherein M>

N, comprising;

means for providing relative spectral intensities C_i of said chemical combination at wavelengths λ

_i ;

means for determining said concentrations X_j from equation

space="preserve" listing-type="equation">X=(A.sup.T A).sup.-1 A.sup.T C

wherein A is a matrix of said relative spectral intensities A_ij, wherein A^T is the transpose of A, and wherein (A^T A)^-1 is the inverse matrix of A^T A, wherein X is a vector of said concentrations X_j, and C is a vector of said relative spectral intensities C_i.

2. An apparatus according to claim 1, wherein said relative spectral intensities A_ij and C_i are absorbance intensities.

3. An apparatus according to claim 1, wherein said means for providing said relative spectral intensities C_i is an absorbance spectrometer.

4. An apparatus according to claim 1, wherein said predetermined relative spectral intensities A_ij are determined using an absorbance spectrometer.

5. An apparatus according to claim 1, wherein said means for determining is a digital computer.

6. An apparatus according to claim 5, wherein said predetermined relative spectral intensities A_ij are stored in said digital computer.

7. An apparatus according to claim 1, wherein if a particular X_j is determined to be less than zero, said particular X_j is set equal to zero.

8. An apparatus according to claim 1, further including a means for generating said relative spectral intensities C_i at a plurality of periodic intervals in time.

9. An apparatus according to claim 8, wherein said interval of time is less than a millisecond.

10. An apparatus according to claim 1, wherein said chemical combination is selected from the group consisting of a solid, a liquid and a gas.

11. An apparatus according to claim 8, wherein said chemical combination is a solid, and further including a means for removing a portion of material at a surface of said solid, said chemical combination being said portion at each of said plurality of said time intervals, a vector X being generated for each of said time intervals, said time interval corresponding to a depth into said surface, further including a means for generating a profile of at least one of said relative concentrations X_j versus said depth.

24. An apparatus according to claim 1, wherein said concentration X_j are selected from the group consisting of relative concentrations and absolute concentrations.

26. An apparatus according to claim 1, further including:

means for storing said C_i as stored relative spectral intensities;

means for storing said A_ij as stored predetermined relative constituent spectral intensities.

27. A structure according to claim 1, wherein said chemical combination is a chemical mixture.

12. An apparatus for determining, at periodic intervals of time, the concentrations X_j of N component chemical constituents, wherein j=1 to N, in a chemical combination using predetermined relative constituent spectral intensities A_ij of said N component chemical constituents, wherein i=1 to M, wherein M>

N, comprising;

means for providing relative spectral intensities C_i of said chemical combination at wavelengths λ

_i at said periodic intervals of time;

means for determining said concentrations X_j from equation

space="preserve" listing-type="equation">X=(A.sup.T A).sup.-1 A.sup.T C

wherein A is a matrix of said relative constituent spectral intensities A_ij, wherein A^T is the transpose of A and wherein (A^T A)^-1 is the inverse matrix of A^T A, wherein X is a vector of said relative concentrations X_j and C is a vector of said relative spectral intensities C_i ;

an electromagnetic radiation source for providing an incident beam containing said λ

_i, said beam having an intensity I₀ (λ

_i) at each of said λ

_i ;

an enclosure through which said chemical combination passes, said enclosure being transparent to said λ

_i ;

a means for directing said incident beam at said enclosure through which said beam passes as a transported beam;

means for measuring each of said I₀ (λ

_i);

means for measuring the intensity I(λ

_i) of the transported beam at each of said λ

_i ;

means for comparing I₀ (λ

_i) and I(λ

_i) for each of said λ

_i to determine each of said C_i ;

means for generating a profile of at least one of said relative concentrations X_j versus said periodic intervals of time.

13. A method for determining the concentrations X_j of N component chemical constituents, wherein j=1 to N, in a chemical combination using predetermined relative constituent spectral intensities A_ij of said N component chemical constituents, wherein i=1 to M, wherein M>

N, comprising the steps of;

providing relative spectral intensities C_i of said chemical combination at wavelengths λ

_i ;

determining said relative concentrations X_j from equation

space="preserve" listing-type="equation">X=(A.sup.T A).sup.-1 A.sup.T C

wherein A is a matrix of said relative spectral intensities A_ij, wherein A^T is the transpose of A, and wherein (A^T A)^-1 is the inverse matrix of A^T A, and X is a vector of said relative concentrations X_j, and C is a vector of said relative spectral intensities C_i.

14. A method according to claim 13, wherein said relative spectral intensities A_ij and C_i are absorbance intensities.

15. A method according to claim 13, wherein said step of generating said relative spectral intensities C_i is using an absorbance spectrometer.

16. A method according to claim 13, wherein said predetermined relative spectral intensities A_ij are determined using an absorbance spectrometer.

17. A method according to claim 13, wherein said step of determining is done using a digital computer.

18. A method according to claim 16, wherein said predetermined relative spectral intensities A_ij are stored in said digital computer.

19. A method according to claim 13, wherein if a particular X_j is determined to be less than zero, said particular X_j is set equal to zero.

20. A method according to claim 13, further including a step of generating said relative spectral intensities C_i at a plurality of periodic intervals in time.

21. A method according to claim 19, wherein said interval of time is less than a millisecond.

22. A method according to claim 13, wherein said chemical combination is selected from the group consisting of a solid, a liquid and a gas.

23. A method according to claim 19, wherein said chemical combination is a solid, and further including a step for removing a portion of material at a surface of said solid, said chemical combination being said portion at each of said plurality of said time intervals, a vector X being generated for each of said time intervals, said time interval corresponding to a depth into said surface, further including a step of generating a profile of at least one of said relative concentrations X_j versus said depth.

25. A method according to claim 13, wherein said concentrations X_j are selected from the group consisting of relative concentrations and absolute concentrations.

28. A method according to claim 13, wherein said chemical combination is a chemical mixture.