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.