Infrared spectrum measuring apparatus adapted for measuring the absorption of infrared radiation by a liquid sample utilizing a total reflection phenomenon of light

• US 5,434,411 A
• Filed: 05/06/1993
• Issued: 07/18/1995
• Est. Priority Date: 05/26/1992
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Watanabe, Yoshio, Miyahara, Yuji, Fujii, Toshiko
• Primary Examiner(s): FIELDS, CAROLYN
• Application Number:
  US08/058,610
• Time in Patent Office: 803 Days
• Field of Search: 250/339, 250/341
• US Class Current: 250/339.07
• CPC Class Codes: G01N 21/552 Attenuated total reflection

Abstract

Infrared radiation is incident on a total reflection plane of a prism and penetrates a liquid sample through a metal layer put between the total reflection plane and the liquid sample in close contact therewith whereby the infrared radiation is partially absorbed by the liquid sample. Alternatively, the liquid sample may be put between the total reflection plane and the metal layer in close contact therewith so that part of the light penetrates the sample from the prism through the total reflection plane to interact with the metal layer and then is caused to reenter into the prism whereby it is partly absorbed by the liquid sample. The metal layer is for enhancing the intensity of the electric field component of the infrared radiation. The incident angle of the infrared radiation on the total reflection plane is so set that the partially absorbed infrared radiation is total-reflected. The total-reflected infrared radiation is detected by a detector so as to obtain an absorption spectrum of the liquid sample by the infrared radiation.

Claims

1. An infrared spectrum measuring apparatus comprising:

a) a prism having a total reflection plane;

b) means for generating infrared radiation and directing the same from the outside of the prism to the inside thereof so as to cause the infrared radiation to be incident on the total reflection plane, wherein the prism has another reflection plane substantially parallel to the total reflection plane so that the infrared radiation is reflected a plurality of times between these reflection planes;

c) a layer disposed so as to come in close contact with the total reflection plane;

d) a sample container comprising means for accommodating a liquid sample, said sample container comprising side walls and said layer,

(i) the layer having its thickness capable of transmitting the infrared radiation therethrough and of causing the same to penetrate the liquid sample so that the infrared radiation is partially absorbed thereby,

(ii) the layer being for enhancing the intensity of an electric field component of the infrared radiation, and

(iii) the incident angle of the infrared radiation on the total reflection plane being so set that the partially absorbed infrared radiation is substantially total-reflected; and

e) means for detecting the total-reflected infrared radiation, wherein the electric field component intensity enhancing layer comprises a metal layer and an organic layer disposed between the prism and the metal layer to come in close contact with them, the organic layer being capable of transmitting the infrared radiation therethrough.

2. The infrared spectrum measuring apparatus according to claim 1, wherein the thickness of the organic layer is substantially less than 1/5 of the wavelength of the infrared radiation.

3. An infrared spectrum measuring apparatus comprising:

a) a prism having a total reflection plane;

b) means for generating infrared radiation and directing the same from the outside of the prism to the inside thereof so as to cause the infrared radiation to be incident on the total reflection plane, wherein the prism has another reflection plane substantially parallel to the total reflection plane so that the infrared radiation is reflected a plurality of times between these reflection planes;

c) a metal-containing layer disposed so as to come in close contact with the total reflection plane;

d) a sample container comprising means for accommodating a liquid sample, said sample container comprising side walls and said metal-containing layer,

(i) the metal-containing layer having its thickness capable of transmitting the infrared radiation therethrough and of causing the same to penetrate the liquid sample so that the infrared radiation is partially absorbed thereby, and

(ii) the incident angle of the infrared radiation on the total reflection plane being so set that the partially absorbed infrared radiation is substantially total-reflected; and

e) means for detecting the total-reflected infrared radiation, wherein the metal-containing layer comprises a metal layer and an organic layer, said organic layer being disposed between the prism and the metal layer to come in close contact with them, the organic layer being capable of transmitting the infrared radiation therethrough.

4. The infrared spectrum measuring apparatus according to claim 3, wherein the thickness of the organic layer is substantially less than 1/5 of the wavelength of the infrared radiation.

5. An infrared spectrum measuring apparatus comprising:

a) an infrared radiation transmitting medium having a total reflection plane;

b) means for generating infrared radiation and directing the same from the outside of the infrared radiation transmitting medium to the inside thereof so as to cause the infrared radiation to be incident on the total reflection plane;

c) a metal layer;

d) a spacer disposed between the total reflection plane and the metal layer for forming therebetween a layer-like space comprising means for holding a liquid sample and bringing the same into close contact with the total reflection plane and the metal layer,

(i) the thickness of the spacer being so set that the infrared radiation is transmitted through the liquid sample and partially absorbed by the same, and

(ii) the incident angle of the infrared radiation on the total reflection plane being so set that the partially absorbed infrared radiation is substantially total-reflected; and

e) means for detecting the total-reflected infrared radiation.

6. The infrared spectrum measuring apparatus according to claim 5, further comprising a plate for supporting the metal layer.

7. An infrared spectrum measuring apparatus comprising:

a) an infrared radiation transmitting medium having a total reflection plane;

b) means for generating infrared radiation and directing the same from the outside of the infrared radiation transmitting medium to the inside thereof so as to cause the infrared radiation to be incident on the total reflection plane;

c) a metal-containing layer;

d) an organic layer being capable of transmitting the infrared radiation therethrough;

d) a spacer disposed between the organic layer and the metal-containing layer for forming therebetween a layer-like space comprising means for holding a liquid sample and bringing the same into close contact with the organic layer and the metal-containing layer,

(i) the thickness of the spacer being so set that the infrared radiation is transmitted through the liquid sample and partially absorbed by the same, and

ii) the incident angle of the infrared radiation on the total reflection plane being so set that the partially absorbed infrared radiation is substantially total-reflected; and

e) means for detecting the total-reflected infrared radiation.

8. The infrared spectrum measuring apparatus according to claim 7, wherein said metal-containing layer comprises a metal layer and a protection solid layer, said protection solid layer disposed between the layer-like space and the metal layer, the protection solid layer being in close contact with the metal layer on one side thereof and the liquid sample when the liquid sample fills the layer-like space on the other side, respectively.

9. The infrared spectrum measuring apparatus according to claim 8, wherein the thickness of the organic layer is substantially less than 1/5 of the wavelength of the infrared radiation.

10. An infrared spectrum measuring apparatus comprising:

a) an infrared radiation transmitting prism having a total reflection plane and another reflection plane substantially parallel thereto;

b) means for generating infrared radiation and directing the same from the outside of the infrared radiation transmitting prism to the inside thereof so as to cause the infrared radiation to be incident on the total reflection plane and be reflected a plurality of times between the two reflection planes;

c) an organic layer disposed so as to come in close contact with the total reflection plane, the organic layer being capable of transmitting the infrared radiation therethrough;

d) a metal layer disposed so as to come in close contact with the organic layer on the opposite side thereof to the total reflection plane;

e) a sample container comprising means for accommodating a liquid sample, said sample container comprising side walls and said metal layer,

(i) the metal layer having its thickness capable of transmitting the infrared radiation therethrough and of causing the same to penetrate the liquid sample so that the infrared radiation is partially absorbed thereby,

(ii) the metal layer being for enhancing the intensity of an electric field component of the infrared radiation, and

(iii) the incident angle of the infrared radiation on the total reflection plane being so set that the partially absorbed infrared radiation is substantially total-reflected; and

f) means for detecting the total-reflected infrared radiation.

11. The infrared spectrum measuring apparatus according to claim 10, wherein the thickness of the organic layer is substantially less than 1/5 of the wavelength of the infrared radiation.

12. An infrared spectrum measuring apparatus comprising:

a) an infrared radiation transmitting prism having a total reflection plane and another reflection plane substantially parallel thereto;

b) means for generating infrared radiation and directing the same from the outside of the infrared radiation transmitting prism to the inside thereof so as to cause the infrared radiation to be incident on the total reflection plane and be reflected a plurality of times between the two reflection planes;

c) an organic layer disposed so as to come in close contact with the total reflection plane, the organic layer being capable of transmitting the infrared radiation therethrough;

d) a metal layer disposed so as to come in close contact with the organic layer on the opposite side thereof to the total reflection plane;

e) a sample container comprising means for accommodating a liquid sample, said sample container comprising side walls and said metal layer,

(i) the metal layer having its thickness capable of transmitting the infrared radiation therethrough and of causing the same to penetrate the liquid sample so that the infrared radiation is partially absorbed thereby, and

(ii) the incident angle of the infrared radiation on the total reflection plane being so set that the partially absorbed infrared radiation is substantially total-reflected; and

f) means for detecting the total-reflected infrared radiation.

13. The infrared spectrum measuring apparatus according to claim 12, wherein the thickness of the organic layer is substantially less than 1/5 of the wavelength of the infrared radiation.

14. An infrared spectrum measuring apparatus comprising:

a) an infrared radiation transmitting medium having a total reflection plane;

b) means for generating infrared radiation and directing the same from the outside of the infrared radiation transmitting medium to the inside thereof so as to cause the infrared radiation to be incident on the total reflection plane;

c) a metal layer;

d) a spacer disposed between the metal layer and the total reflection plane for forming therebetween a layer-like space comprising means for holding a liquid sample and bringing the same into close contact with the total reflection plane and the metal layer,

(i) the thickness of the spacer being so set that the infrared radiation is transmitted through the liquid sample and partially absorbed by the same, and

(ii) the incident angle of the infrared radiation on the total reflection plane being so set that the partially absorbed infrared radiation is substantially total-reflected;

e) a plate disposed so as to come in close contact with the metal layer on the opposite side thereof to the spacer for supporting the metal layer; and

f) means for detecting the total-reflected infrared radiation.

15. An infrared spectrum measuring apparatus comprising:

a) an infrared radiation transmitting medium having a total reflection plane;

b) means for generating infrared radiation and directing the same from the outside of the infrared radiation transmitting medium to the inside thereof so as to cause the infrared radiation to be incident on the total reflection plane;

c) an organic layer disposed so as to come in close contact with the total reflection plane;

d) a metal layer;

e) a spacer disposed between the organic layer and the metal layer for forming therebetween a layer-like space comprising means for holding a liquid sample and bringing the same into close contact with the organic layer and the metal layer,

(i) the thickness of the spacer being so set that the infrared radiation is transmitted through the liquid sample and partially absorbed by the same, and

(ii) the incident angle of the infrared radiation on the total reflection plane being so set that the partially absorbed infrared radiation is substantially total-reflected; and

f) means for detecting the total-reflected infrared radiation.

16. An infrared spectrum measuring apparatus comprising:

a) an infrared radiation transmitting medium having a total reflection plane;

b) means for generating infrared radiation and directing the same from the outside of the infrared radiation transmitting medium to the inside thereof so as to cause the infrared radiation to be incident on the total reflection plane;

c) an organic layer disposed so as to come in close contact with the total reflection plane;

d) a protection solid layer;

e) a spacer disposed between the organic layer and the protection solid layer for forming therebetween a layer-like space comprising means for holding a liquid sample and bringing the same into close contact with the organic layer and the protection solid layer,

f) a metal layer disposed so as to come in close contact with the protection solid layer on the opposite side thereof to the spacer,

(i) the thickness of the spacer being so set that the infrared radiation is transmitted through the liquid sample and partially absorbed by the same, and

(ii) the incident angle of the infrared radiation on the total reflection plane being so set that the partially absorbed infrared radiation is substantially total-reflected; and

g) means for detecting the total-reflected infrared radiation.

17. The infrared spectrum measuring apparatus according to claim 16, wherein the thickness of the organic layer is substantially less than 1/5 of the wavelength of the infrared radiation.