Gas phase cooling and mixture analysis
A system includes a cold cell tube configured to receive a mixture of a target gas and a buffer gas to cool the target gas to a temperature at which a partial pressure of the target gas is greater than the saturated vapor pressure of the target gas while maintaining at least a portion of the target gas in the gas phase. The system also includes a spectroscopic module configured to detect the cooled target gas in the cold cell tube; and an analysis module configured to determine a characteristic of the target gas based on the results of the detecting.
1. A system comprising:
a cold cell tube configured to receive a mixture of a target gas and a buffer gas to cool the target gas to a temperature at which a partial pressure of the target gas is greater than the saturated vapor pressure of the target gas while maintaining at least a portion of the target gas in the gas phase;
a spectroscopic module configured to detect the cooled target gas in the cold cell tube; and
an analysis module configured to determine a characteristic of the target gas based on the results of the detecting.
2. The system of claim 1 , wherein the target gas includes a plurality of chemical species and the characteristic of the target gas includes an identity of at least one of the chemical species.
3. The system of claim 2 , wherein the cold cell tube is configured to cool the target gas to a temperature at which a partial pressure of each chemical species is greater than the saturated vapor pressure of that chemical species.
4. The system of claim 2 , wherein, for at least one of the chemical species included in the target gas, an elastic scattering cross section between a molecule of the at least one chemical species and a molecule of the buffer gas is greater than an elastic scattering cross section between a first molecule of the buffer gas and a second molecule of the buffer gas.
5. The system of claim 1 , wherein the cold cell tube is configured to increase a phase space density of the target gas.
6. The system of claim 1 , wherein the cold cell tube is configured to cool the target gas to a temperature at which single vibrational lines of the target gas are spectroscopically resolvable by the spectroscopic module.
7. The system of claim 1 , further comprising:
an input module configured to receive the mixture of the target gas and the buffer gas; and
a transition tube disposed between the input module and the cold cell tube.
8. The system of claim 7 , wherein the input module includes a capillary gas chromatograph configured to receive the mixture of the target gas and the buffer gas.
9. The system of claim 7 , wherein the input module includes a cryogenic plate configured to condense at least some components of the target gas.
10. The system of claim 9 , further comprising:
a heating element configured to heat the cryogenic plate,
wherein, when the cryogenic plate is heated, at least some components of the target gas are released to the transition tube.
11. The system of claim 1 , wherein the spectroscopic module comprises:
a light source configured to excite the cooled target gas; and
an emissions detector configured to detect at least one of a fluorescence emitted by at least one component of the target gas in response to the excitation and an absorption by at least one component of the target gas in response to the excitation.
12. The system of claim 11 , wherein the light source includes a tunable laser configured to emit light at a wavelength capable of exciting the fluorescence of at least one component of the target gas.
13. The system of claim 11 , wherein the light source includes a light source configured to emit a plurality of wavelengths; and a monochromator.
14. The system of claim 1 , wherein the spectroscopic module comprises:
a microwave source configured to excite the cooled target gas; and
a microwave detector configured to detect at least one of absorption or emission of microwaves by at least one component of the target gas in response to the excitation.
15. The system of claim 1 , wherein the spectroscopic module comprises:
a broadband infrared light source configured to excite the cooled target gas; and
a detector configured to detect an absorption by at least one component of the target gas in response to the excitation according to Fourier Transform Infrared (FTIR) scanning absorption.
16. The system of claim 1 , wherein the cold cell tube is configured to cool the target gas without substantially changing a density of the target gas.
17. A method comprising:
receiving a mixture of a target gas and a buffer gas;
cooling the target gas to a temperature at which a partial pressure of the target gas is greater than the saturated vapor pressure of the target gas while maintaining at least a portion of the target gas in the gas phase;
spectroscopically detecting the cooled target gas; and
determining a characteristic of the target gas based on the results of the detecting.
18. The method of claim 17 , wherein the target gas includes a plurality of different chemical species and wherein determining a characteristic of the target gas includes identifying at least one of the chemical species.
19. The method of claim 18 , wherein cooling the target gas includes cooling the target gas to a temperature at which a partial pressure of each chemical species is greater than the saturated vapor pressure of that chemical species.
20. The method of claim 18 , wherein, for at least one of the chemical species included in the target gas, an elastic scattering cross section between a molecule of the at least one chemical species and a molecule of the buffer gas is greater than an elastic scattering cross section between a first molecule of the buffer gas and a second molecule of the buffer gas.
21. The method of claim 17 , wherein cooling the target gas includes increasing a phase space density of the target gas.
22. The method of claim 17 , wherein cooling the gas includes cooling the gas to a temperature at which single vibrational lines of the target gas are spectroscopically resolvable.
23. The method of claim 17 , further comprising receiving the mixture of the target gas and the buffer gas in an input module.
24. The method of claim 23 , wherein receiving the mixture in the input module includes receiving the mixture of the target gas and the buffer gas in a capillary gas chromatograph.
25. The method of claim 23 , wherein receiving the mixture in the input module includes condensing at least some components of the target gas on a cryogenic plate.
26. The method of claim 25 , further comprising heating the cryogenic plate, wherein, when the cryogenic plate is heated, at least some components of the target gas are released.
27. The method of claim 17 , wherein spectroscopically detecting the cooled target gas includes optically detecting the cooled target gas.
28. The method of claim 27 , wherein optically detecting the target gas includes:
exciting the target gas using a light source; and
detecting at least one of a fluorescence emitted by at least one component of the target gas in response to the excitation and an absorption by at least one component of the target gas in response to the excitation.
29. The method of claim 17 , wherein spectroscopically detecting the cooled target gas includes:
exciting the target gas using a microwave source; and
detecting at least one of absorption or emission of microwaves by at least one component of the target gas in response to the excitation.
30. The method of claim 29 , wherein spectroscopically detecting the cooled target gas includes detecting the cooled target gas using pulsed Fourier Transform Microwave Spectroscopy.
31. The method of claim 17 , wherein cooling the target gas includes cooling the target gas without substantially changing a density of the target gas.