Optics: measuring and testing – For light transmission or absorption
Reexamination Certificate
2001-09-20
2003-08-26
Font, Frank G. (Department: 2877)
Optics: measuring and testing
For light transmission or absorption
C356S435000
Reexamination Certificate
active
06611333
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an isotopomer absorption spectral analyzing apparatus and method for precisely assaying an isotopomer—a molecule containing an isotope—for inferring the origin thereof, contemplating applications in scientific fields, including environmental analysis; applications in the medical field, including diagnosis; and applications in other fields.
BACKGROUND ART
Conventional absorption spectral analyzing apparatuses employ a sample cell having a single optical path.
DISCLOSURE OF THE INVENTION
Therefore, when the isotope abundance ratio (the abundance ratio between two isotopes) deviates greatly from 1:1, a great difference is present between the levels of absorption signals corresponding to the isotope species, depending on the species of the isotopes. For example, in the case of naturally occurring CH
4
, the abundance ratio of
12
CH
4
to
13
CH
4
is approximately 100:1, and therefore, the absorption signal level of
12
CH
4
is approximately 100 times that of
13
CH
4
, making precise measurement of the isotope ratio difficult.
The present invention has been accomplished so as to solve the aforementioned problem. Thus, an object of the present invention is to provide an isotopomer absorption spectral analyzing apparatus and method which enable absorption signals corresponding to different isotopes to assume substantially the same level, to thereby enable precise measurement of the isotope ratio.
In order to achieve the above objects, the present invention provides the following.
[1] An isotopomer absorption spectral analyzing apparatus, characterized in that a sample cell having a single window for introduction of at least two optical beams into the cell and being capable of providing optical paths of different optical lengths is installed; at least two optical beams are caused to enter the sample cell such that the optical beams travel along optical paths of different optical path lengths; and the abundance ratio between species of isotopes in molecules is determined from the ratio between intensities of absorption signals corresponding to the species of isotopes.
[2] An isotopomer absorption spectral analyzing apparatus as described in [1], wherein the at least two optical beams are emitted from a single light source of variable-wavelength type or from a plurality of light sources of fixed-wavelength type or variable-wavelength type.
[3] An isotopomer absorption spectral analyzing apparatus as described in [1], wherein the sample cell is a multiple-reflection absorption cell having paired reflection mirrors.
[4] A method of isotopomer absorption spectral analysis, characterized in that a sample cell having a single window for introduction of at least two optical beams into the cell and being capable of providing optical paths of different optical lengths is used in order to substantially equalize levels of absorption signals corresponding to species of isotopes, to thereby enable precise measurement of the abundance ratio between the species of isotopes.
REFERENCES:
Chemosphere Chem Biol Toxicol Relat Environ Probl, vol. 26, Nos. 1-4, pp. 13-22, 1993.
Kikugawa Tomoyuki
Uehara Kiyoji
Yoshida Naohiro
Font Frank G.
Japan Science and Technology Corporation
Lorusso, Loud & Kelly
Merlino Amanda
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