초록

Optical cells are non-actively compensated to ensure that a sample gap of a sample space remains nearly constant upon a change in temperature. Fluids can be flowed through the sample space of the optical cells.

대표청구항 ▼

What is claimed is: 1. An optical cell, comprising: a front plate having a first optical window through which an incident light beam can pass; a back plate; a spacer in contact with the front plate and the back plate, the spacer being separable from the front plate and the back plate; the front and

What is claimed is: 1. An optical cell, comprising: a front plate having a first optical window through which an incident light beam can pass; a back plate; a spacer in contact with the front plate and the back plate, the spacer being separable from the front plate and the back plate; the front and back plates and the spacer defining a sample space capable of containing a sample and having a sample gap between the front plate and the back plate; a frame in contact with the front plate and with the back plate; the front plate, back plate, spacer, and frame having coefficients of linear expansion and height dimensions so that the optical cell is spectroscopically stable with respect to varying temperature of the sample space in a temperature range of experimentation. 2. The optical cell of claim 1, wherein the volume of the sample space is less than or equal to about 20 microliters. 3. The optical cell of claim 1, wherein the volume of the sample space is less than or equal to about 5 microliters. 4. The optical cell of claim 1, wherein the smallest dimension of the sample space in a plane parallel to the first optical window is at least about five times the sample gap. 5. The optical cell of claim 1, wherein a sample that comprises a solid can be placed into and removed from the sample space. 6. The optical cell of claim 1, wherein the sample space may receive a liquid sample. 7. The optical cell of claim 1, further comprising at least one fluid inlet, wherein a liquid sample can flow through the fluid inlet, into the sample space, and out of the sample space. 8. The optical cell of claim 1, the front plate, back plate, spacer, and frame being selected to have coefficients of linear expansion and height dimensions so that the sample gap changes with temperature by no more than 5 nm per Kelvin temperature change of the sample space in a temperature range of spectroscopic measurement. 9. The optical cell of claim 1, the front plate, back plate, spacer, and frame being selected to have coefficients of linear expansion and height dimensions so that, without active correction, the sample gap changes with temperature by no more than 3 nm per Kelvin temperature change of the sample space in a temperature range of spectroscopic measurement. 10. The optical cell of claim 1, wherein the sample gap is in a range of from about 0.1 μm to about 3 μm. 11. The optical cell of claim 1, the frame comprising a holder, a compensating plate, and a compression plate. 12. The optical cell of claim 11, wherein the holder, the compression plate, and the compensating plate each comprise a material selected from the group consisting of red brass, brass, copper, zinc, aluminum, steel, and alloys thereof. 13. The optical cell of claim 11, wherein the compression plate is formed of the same material as the holder. 14. The optical cell of claim 11, the frame further comprising a first outer gasket and a second outer gasket. 15. The optical cell of claim 14, wherein the outer gaskets each comprise a material selected from the group consisting of aluminum, gold, silver, and copper. 16. The optical cell of claim 1, wherein when a polyacrylamide gel sample in a water bath liquid in the sample space has a measured peak in the spectrum with an absorbance from 0.3 to 1.5 absorbance units within the range of 2000 cm-1 to 700 cm-1, and the water bath liquid is exchanged with fresh water bath liquid and the spectrum is remeasured four additional times, the standard deviation of the absorbance of the measured peak will be within 0.3%. 17. The optical cell of claim 16, wherein the standard deviation of the absorbance of the measured peak will be within about 0.03%. 18. The optical cell of claim 1, the front plate, back plate, spacer, and frame being selected to have coefficients of linear expansion and height dimensions so that the difference between the maximum sample gap and the minimum sample gap is no greater than 80 nm during a temperature change of 50 K. 19. The optical cell of claim 1, the front plate, back plate, spacer, and frame being selected to have coefficients of linear expansion and height dimensions so that the difference between the maximum sample gap and the minimum sample gap is no greater than 10 nm during a temperature change of 50 K. 20. The optical cell of claim 1, the back plate having a second optical window. 21. The optical cell of claim 1, the front plate, back plate, spacer, and frame being selected to have coefficients of linear expansion and height dimensions so that when the first optical window is of zinc selenide, water is the sample, and the temperature in the sample space is maintained constant, for a peak at 1644 cm-1 in the water spectrum with an absorbance of 0.5 absorbance units, the absorbance of the peak remains stable within about 5��10-4 absorbance units over two weeks. 22. The optical cell of claim 21, wherein the absorbance of the peak remains stable within about 1��10-4 absorbance units over two weeks. 23. The optical cell of claim 1, wherein the spectrum of a solvent sample in the sample space is obtained, the spectrum of a solution including a trace component and the solvent is obtained, the trace component spectrum has a marker peak, the solvent spectrum has a masking peak which overlaps with the marker peak, a difference spectrum is obtained from subtraction of the solvent spectrum multiplied by the volume fraction of the solvent in the solution, the masking peak of the solvent in the spectrum of the solution is greater than or equal to about 0.3 absorbance units, and the intensity of the marker peak of the trace component in the difference spectrum is less than or equal to about 10-3 absorbance units. 24. The optical cell of claim 1, wherein when the back plate has a second optical window, the first optical window and the second optical window comprise calcium fluoride, the sample gap is about 5 μm, the sample space is maintained at about 25�� C., the spectrum of a water sample in the sample space is measured in transmission mode, the spectrum of a sample of a solution of 0.005 vol % of N-methyl-formamide in water in the sample space is measured in transmission mode, the water spectrum is scaled by the volume fraction of water and the scaled spectrum is subtracted from the solution spectrum to obtain a difference spectrum, the determined absorption of the peak induced by N-methyl-formamide at 1659 cm-1 is from about 1��10-4 to about 2��10-4 absorption units. 25. The optical cell of claim 1, wherein the first optical window comprises a material selected from the group consisting of calcium fluoride, magnesium fluoride, barium fluoride, zinc selenide, and diamond. 26. The optical cell of claim 1, the back plate comprising a second optical window, wherein the second optical window comprises a material selected from the group consisting of calcium fluoride, magnesium fluoride, barium fluoride, zinc selenide, and diamond. 27. The optical cell of claim 1, the back plate having a second optical window, wherein the first optical window and the second optical window comprise calcium fluoride. 28. The optical cell of claim 1, wherein the spacer comprises at least one of silicone vacuum grease, fluorinated silicone vacuum grease, polytetrafluoroethylene, polyethylene terephthalate, polyethylene, and polypropylene. 29. The optical cell of claim 1, further comprising a heating/cooling element. 30. The optical cell of claim 29, wherein the heating/cooling element includes a Peltier plate. 31. A spectroscopy system, comprising the optical cell of claim 1 and a spectrometer, which directs an incident light beam onto a sample contained within the sample space and receives a light transmitted, reflected, or emitted by the sample. 32. The spectroscopy system of claim 31, wherein a kinetic process occurring on or within the sample with a process time of less than or equal to about 0.2 seconds can be identified by the spectrometer. 33. The spectroscopy system of claim 31, wherein a kinetic process occurring on or within the sample with a process time of less than or equal to about 0.001 seconds can be identified by the spectrometer. 34. The optical cell of claim 1, wherein the front plate, back plate, and spacer are capable of containing a solid sample or a gel sample within the sample space. 35. The optical cell of claim 1, wherein the optical cell is mounted in a microscope mounting. 36. A method comprising placing a sample in an optical cell according to claim 1, directing an incident light beam at the sample, and measuring the spectrum of light transmitted through, reflected by, emitted by, or scattered by the sample. 37. The optical cell of claim 1, the front plate, back plate, spacer, and frame being selected to have coefficients of linear expansion and height dimensions so that the sample gap changes with temperature by no more than 5 nm per Kelvin temperature change of the sample space in a temperature range of experimentation. 38. The optical cell of claim 37, wherein the front plate comprises an optical window, wherein the frame comprises a compensating plate, a first outer gasket, a second outer gasket, and a holder, the optical window having a coefficient of linear expansion αow and a height dimension dow, the back plate having a coefficient of linear expansion αbp and a height dimension dbp, the compensating plate having a coefficient of linear expansion αcp, and a height dimension dcp, the first outer gasket having a coefficient of linear expansion αg1 and a height dimension dg1, the second outer gasket having a coefficient of linear expansion αg2 and a height dimension dg2, the spacer having a height dimension ds, and the holder having a coefficient of linear expansion αh, wherein upon a change of temperature ΔT, the size of the sample gap changes as ΔT(αh(dow+dbp+ds+dcp +dg1+dg2)-(αowdow+α bpdbp+αcpdcp+αg1d g1+αg2dg2)), and wherein upon a 1 Kelvin change of temperature, the sample gap changes by no more than 5 nm. 39. The optical cell of claim 1, the front plate, back plate, spacer, and frame being selected to have coefficients of linear expansion and height dimensions so that, without active correction, the sample gap changes with temperature by no more than 3 nm per Kelvin temperature change of the sample space in a temperature range of experimentation. 40. A method for obtaining an optical spectrum of a sample, comprising: placing the sample in a sample space of an optical cell, the sample space defined by a front plate having a first optical window, a back plate, and a spacer, the sample space having a thermomechanically stable sample gap between the first optical window in the front plate and the back plate, directing an incident light beam to pass through the first optical window and into the sample space to impinge on the sample; measuring the spectrum of light transmitted through, reflected by, emitted by, or scattered by the sample; wherein the sample gap is thermomechanically stable when the temperature of the sample space is varied in a temperature range of experimentation. 41. The method of claim 40, wherein the incident light beam is directed to impinge directly on the sample in the sample space without being reflected by the back plate or by the spacer before impinging on the sample. 42. The method of claim 40, wherein the light transmitted through, reflected by, emitted by, or scattered by the sample is reflected at most once by the back plate or by the spacer while traveling through the sample. 43. The method of claim 40, wherein the incident light beam contains light having a wavelength in the range of from about 0.1 μm to about 50 μm. 44. The method of claim 40, comprising measuring the infrared, visible, or ultraviolet spectrum of light transmitted through, reflected by, emitted by, or scattered by the sample. 45. The method of claim 40, wherein the incident light beam is directed to pass through the first optical window into the sample space with an angle of incidence at an interface between the first optical window and the sample space less than or equal to about 95% of the critical angle. 46. The method of claim 40, wherein a bath fluid in the sample space is exchanged within less than or equal to about 0.2 seconds. 47. The method of claim 40, wherein the sample comprises a solid, comprising separating the spacer from the front plate or from the back plate to place the sample in or to remove the sample from the sample space. 48. The method of claim 40, further comprising providing a heating/cooling element, in contact with the frame; and ramping the temperature of the heating/cooling element according to a predetermined schedule while measuring the spectrum of light transmitted through, reflected by, emitted by, or scattered by the sample.