D. SMM/THz Gas Sensors: A SMM/THz gas sensor needs a core spectrometer, such as described in Section V.C, packaged with a gas sampling system and appropriate operations software. We have recently described such a system [1]. The sensor is self-contained, including gas handling and computation, in a standard 19 in equipment rack format, with a height of 5.25 in and a depth of 18 in. Its core spectrometer provides absolute specificity (probability of false alarm <<10-10) on a mixture of 32 gases. It is capable of automated analysis with a cycle time of <10 minutes and returns quantitative results for each gas in the mixture. The system can analyze either a prepared mixture or a dilute sample of air via automated and software selectable sorbent preconcentration strategies. In the sorbent mode a sensitivity of ~ 2 ppt is demonstrated for acetonitrile.
V.D.1 Strategies and Design Space
V.D.2 The Vacuum Preconcentration System
V.D.3 Sorbent Tubes and Sorbent Material Selection