Buffer gas cooling and mixture analysis
An apparatus for spectroscopy of a gas mixture is described. Such an apparatus includes a gas mixing system configured to mix a hot analyte gas that includes at least one analyte species in a gas phase into a cold buffer gas, thereby forming a supersaturated mixture to be provided for spectroscopic analysis.
1. An apparatus for spectroscopic analysis, comprising:
a gas mixing system configured to mix a hot analyte gas that includes at least one analyte species into a cold buffer gas, thereby forming a gas mixture; and
a spectroscopy module configured to characterize the gas mixture,
wherein the gas mixing system includes:
an analyte gas transport system configured to propel the hot analyte gas at a first temperature toward a volume in which the hot analyte gas is mixed with the cold buffer gas; and
a buffer gas transport system configured to propel the cold buffer gas at a second temperature toward the volume, the second temperature being lower than the first temperature.
2. The apparatus of claim 1 , wherein the first temperature is at least 294 K, and the second temperature is up to 12 K.
3. The apparatus of claim 1 , wherein the analyte gas transport system is configured to propel the hot analyte gas at a flow rate no greater than 2 sccm.
4. The apparatus of claim 1 , wherein the buffer gas transport system is configured to propel the cold buffer gas at a flow rate in the range of 1 sccm to 10 sccm.
5. The apparatus of claim 1 , further comprising a cold cell to receive the gas mixture, the cold cell including walls defining an interior chamber and a first aperture connecting the interior chamber to a first space external to the cold cell.
6. The apparatus of claim 5 , wherein the analyte gas transport system includes an injection tube configured to propel the hot analyte gas across a gap and toward the first aperture.
7. The apparatus of claim 5 , wherein the volume in which the hot analyte gas is mixed with the cold buffer gas includes at least a portion of the first space external to the cold cell.
8. The apparatus of claim 5 , wherein the volume in which the hot analyte gas is mixed with the cold buffer gas includes at least a portion of the interior chamber of the cold cell.
9. The apparatus of claim 5 , wherein a density of the cold buffer gas adjacent to the first aperture is up to 10 16 atoms cm −3 .
10. The apparatus of claim 5 , wherein the buffer gas transport system is configured to propel the cold buffer gas into the first space external to the cold cell.
11. The apparatus of claim 5 , wherein the buffer gas transport system is configured to propel the cold buffer gas into the interior chamber of the cold cell.
12. The apparatus of claim 5 , further comprising an annular manifold disposed in a periphery of the first aperture, and the buffer gas transport system is configured to propel the cold buffer gas through the annular manifold.
13. The apparatus of claim 5 , wherein the spectroscopy module is configured to characterize the gas mixture within the cold cell.
14. The apparatus of claim 5 , wherein the walls of the cold cell define a second aperture connecting the interior chamber to a second space external to the cold cell.
15. The apparatus of claim 14 , wherein the spectroscopy module is configured to characterize the gas mixture within the second space.
16. A method for spectroscopic analysis, comprising:
mixing an analyte gas at a first temperature with a buffer gas at a second temperature lower than the first temperature, thereby forming a supersaturated gas mixture; and
directing the gas mixture to enter a cold cell,
wherein mixing the analyte gas with the buffer gas includes:
propelling the analyte gas at the first temperature toward a volume in which the analyte gas is mixed with the buffer gas; and
propelling the buffer gas at the second temperature toward the volume.
17. The method of claim 16 , wherein the first temperature is at least 294 K, and the second temperature is up to 12 K.
18. The method of claim 16 , wherein
a density of the buffer gas within the volume is up to 10 16 atoms cm −3 .
19. The method of claim 16 , further comprising characterizing the gas mixture with a spectroscopy module when the gas mixture is within the cold cell.
20. The method of claim 16 , further comprising characterizing the gas mixture with a spectroscopy module when the gas mixture is in a space external to the cold cell.