A constant demand exists to improve the sensitivity of trace chemical species measurement systems, which is often limited by the performance of the infrared photon detector components. The significant cooling required to reduce dark currents and increase detectivities is a practical concern associated with these infrared detectors. For geostationary and low-Earth orbital platforms, passive cooling systems have been developed to provide a suitable means of incorporating such high-performance infrared detectors. The passive cooling system for the Crosstrack Infrared Sounder has provided a means to achieve a set point of 81 K for long-wavelength infrared detector operation. We will develop in this proposed effort the technology for high-performance, passively-cooled infrared (6-14 microns spectral range) detectors with integrated capabilites for Fabry-Perot spectroscopy. The proposed sensors will be based on HgCdTe material for high detectivities and use an Auger-suppression technique to reduce cooling requirements. HgCdTe detectors capable of operating under passive cooling conditions will be designed, fabricated and tested. In parallel, Fabry-Perot cavities suitable for future integration with the HgCdTe infrared detectors will be designed, fabricated and tested. The infrared detector arrays and tunable Fabry Perot cavities will be integrated in later phases of the proposed project.