Ultra high spectral resolution observations of planetary atmospheres using the Cologne tuneable heterodyne infrared spectrometer

Abstract High-resolution spectroscopy is a versatile tool to study planetary atmospheres. In the mid infrared wavelength regime the highest possible spectral resolution is provided by applying heterodyne techniques. At spectral resolution of more than 10 5 observations of fully resolved molecular features are possible allowing retrieval of many physical parameters from single lines. In addition, due to the fact that many of the observed species are abundant also in the Earth's atmosphere, high-resolution measurements allow to peak through the telluric features and lead to less ambiguity than low-resolution data. The paper will present a detailed description of the Cologne-based receiver THIS, the only tuneable heterodyne infrared spectrometer for application to astronomy offering access to the 7– 17 μ m wavelength region at a resolution of up to 3 × 10 7 and a bandwidth of 3 GHz. An overview of the science addressable with THIS will be given as well as a brief introduction to the theory of heterodyning in the infrared including a comparison to direct detection instrumentation.

[1]  R. Schieder,et al.  High spatial resolution mapping of Mars mesospheric zonal winds by infrared heterodyne spectroscopy of CO2 , 2006 .

[2]  D. Buhl,et al.  Tunable diode-laser heterodyne spectrometer for remote observations near 8 microm. , 1982, Applied optics.

[3]  R. Schieder,et al.  Evaluation of quantum-cascade lasers as local oscillators for infrared heterodyne spectroscopy. , 2005, Applied optics.

[4]  A. Betz,et al.  Infrared heterodyne spectroscopy of CO2 on Mars , 1974, Nature.

[5]  R. Schieder,et al.  High-resolution observations of Martian non-thermal CO$\mathsf{_2}$ emission near 10 $\mathsf{\mu}$m with a new tuneable heterodyne receiver , 2005 .

[6]  M. Mumma,et al.  Remote sensing by IR heterodyne spectroscopy. , 1983, Applied optics.

[7]  D. Deming,et al.  Absolute wind velocities in the lower thermosphere of Venus using infrared heterodyne spectroscopy , 1991 .

[8]  J. L. Hall,et al.  Kilohertz linewidth from frequency-stabilized mid-infrared quantum cascade lasers. , 1999, Optics letters.

[9]  R. Menzies.  Laser heterodyne detection techniques , 1976 .

[10]  R. Schieder,et al.  High‐resolution infrared spectroscopy of ethane in Titan's stratosphere in the Huygens epoch , 2006 .

[11]  Alan T. Tokunaga,et al.  Titan's stratospheric zonal wind, temperature, and ethane abundance a year prior to Huygens insertion , 2005 .

[12]  G. Winnewisser,et al.  High-sensitivity mid-infrared heterodyne spectrometer with a tunable diode laser as a local oscillator. , 1998, Applied Optics.

[13]  M M Abbas,et al.  Sensitivity limits of an infrared heterodyne spectrometer for astrophysical applications. , 1976, Applied optics.

[14]  D. Jaffe,et al.  TEXES: A Sensitive High-Resolution Grating Spectrograph for the Mid-Infrared , 2001, astro-ph/0110521.

[15]  P. Romani,et al.  Infrared studies of hydrocarbons on Jupiter , 1989 .

[16]  R. T. Ku,et al.  High-sensitivity infrared heterodyne radiometer using a tunable-diode-laser local oscillator. , 1977, Optics letters.

[17]  E. David Hinkley,et al.  Laser monitoring of the atmosphere , 1976 .

[18]  R. Schieder.  High resolution diode laser and heterodyne spectroscopy with applications toward remote sensing , 1994 .

[19]  P. Bernath,et al.  High-Resolution Infrared Measurements of H2O and SiO in Sunspots , 2006 .

[20]  D. Buhl,et al.  Direct measurement of winds on Titan , 2001 .

[21]  Guido Sonnabend,et al.  Tuneable Heterodyne Infrared Spectrometer for atmospheric and astronomical studies. , 2002, Applied optics.

[22]  D. Buhl,et al.  Ozone abundance on Mars from infrared heterodyne spectra: I. Acquisition, retrieval, and anticorrelation with water vapor , 2006 .

[23]  M. Taguchi,et al.  Ground-based remote sensing of methane height profiles with a tunable diode laser heterodyne spectrometer , 1995 .