High-resolution observations of Martian non-thermal CO2emission near 10 $\mathsf{\mu}$m with a new tuneable heterodyne receiver

Abstract

We present first observations with the Tuneable Heterodyne Infrared Spectrometer (THIS). This instrument developed at University of Cologne has the potential to cover the mid-infrared from 7 to 19 μm. By using heterodyne techniques and an acousto optical spectrometer (AOS) as a back-end the frequency resolution achieved is better than 107 at 10 μm. A tuneable quantum-cascade laser (QCL) is used as a local-oscillator (LO) and the instantaneous bandwidth supplied by the mercury-cadmium-telluride (MCT) detector and the AOS is 1.4 GHz. The system operates within a factor of two of the quantum limit. During December 2003 THIS was installed at the 1.5 m McMath-Pierce solar telescope on Kitt Peak/Arizona. Observations of molecular line features from the atmosphere of Mars were carried out. We present measurements of narrow non-LTE CO2 emission from the Martian atmosphere observed with a never before achieved frequency resolution of 1 MHz. The first analysis suggests zonal winds in the mesosphere of Mars in good agreement with model predictions.