Facility name: SPIROU FTS spectrometer

Location: Institut de Planétologie et Astrophysique de Grenoble
CNRS - Université Grenoble Alpes
Saint Martin d’Hères, France

Persons in charge:

- Scientific : Bernard Schmitt, Research director & Pierre Beck, Assistant Professor
- Technical : Olivier Brissaud, Engineer

General description

SPIROU, is a Fourier transform spectrometer fitted with a cryogenic ultra-high vacuum cell (closed cycle He cryocooler) allowing to measure the transmission spectra of samples from the Near to mid-infrared (10000-400 cm-1, resolution down to 0.25 cm-1) [Quirico and Schmitt 1997a]. The temperature can be set from room temperature down to 10 K with high accuracy (< ±0.1K) over the whole temperature range and vacuum can reach down to 10-9 mbar.

The nominal sample holder at the tip of the cryostat is a simple 2.5 cm diameter window made of various materials (KBr, CsI, Saphire, or Polyethylene) depending on the spectral range studied. The sample is condensed on this window from the gas phase of well-known composition prepared in a gas mixture line equipped with several high accuracy pressure gauges. The condensation rate and thickness of the sample are monitored by He-Ne laser interferences both in reflection and transmission through the sample. The sample thickness can vary typically between 0.1 µm and a few hundred microns but mostly limited by scattering behaviour and thermal conductivity of the sample. One major limitation of this system is the maximum temperature at which the sample is stable under vacuum (sublimation rates « ~ 1 µm/hour).

A series of closed cells have been specifically designed to grow thick (from 50 µm to 1 cm) mono/poly crystalline samples under thermodynamic equilibrium and measure their transmission spectra at low to high temperature, up and above the melting point. These cell are either filled by liquid through the liquefaction of gas at low temperature or manually with liquid at room temperature and the crystal is then grown very slowly (few mm/day) under a weak and controlled thermal gradient. Direct condensation of some solids can also be performed (e.g. CO2 ice). The system can also accept pressed pellets (13 mm diameter) of KBr or PE mixed with finely grinded materials.

Due to its wide range of sample thicknesses this system allowed to measure a large number of transmission spectra and optical constants of ices, hydrates, organic molecules and sulphur-bearing compounds from the visible to the Far-IR (Quirico et al. 1996; Quirico and Schmitt 1997a, b; Grundy et al. 1993, 2002; Grundy and Schmitt 1998; Merlin et al. 2012; Trotta and Schmitt 1996; Schmitt et al. 1994, 1998; Schmitt and Rodriguez 2003) as well as meteorite pellets, …(Beck et al. 2014) . It also allowed the study of kinetics of isotopic exchanges between simple organic molecules and water ice at low temperature (Ratajczak et al. 2009, Faure et al. 2015).

Short description

This spectrometer is a commercial instrument equipped with ultrahigh vacuum cryogenic optical cells specially designed to measure the transmission spectra at low temperature of volatile materials over the Near to mid-IR ranges.

Technical characteristics:

- Type: Laboratory
- Spectrometer type: Fourier transform
- Model : Brucker 70v
- Mode: Transmission
- Spectral range : 0.8 - 25 μm in 2 beamsplitter /detector sets
- Spectral resolution : variable, mini : 0.25 cm-1 (2 cm-1 for far-IR)

- Beam incidence: 0° ± 5° to 0° ± 15° (depends on aperture)
- Spot diameter (focus): 2 to 10 mm (depends on aperture)
- Photometry: absolute: better than 0.1%
- Signal to Noise : > 5000 over most of the range (resolution dependent)

Sample: - compartment: ultrahigh vacuum cryogenic optical cell
- pressure 10-9 to 10-4 mbar
- temperature: 15 - 350 K

Sample holder #1

• type transparent substrate (KBr, CsI or MgF2 window)
• sample type thin films of volatile molecular solids (condensed under vacuum) minerals (thin layers on substrate, or free thick slice)
• texture: amorphous or polycristals (optical quality)
• sample size: 20 mm (diameter)
• sample thickness: < 0.1 μm to 100 μm
• temperature : 10 - 350 K (limited by sublimation temperature)
• pressure 10-9 to 10-4 mbar

Sample holder #2

• type closed cell (MgF2, Al2O2, CaF2 windows)
• sample type crystals of volatile molecular solids (grown from liquid or gas)
• texture : monocrystal to polycristals (optical quality)
• sample size : 15 mm (diameter)
• sample thickness 50 μm to 10 mm
• temperature : 15 - 350 K (limited by saturation pressure)
• pressure 10-4 mbar to 5 bar

- Experiment control : PC fully software controlled.

- Acquisition time : typical 1 mn for 100 scans @ 1 cm-1 resol. in near-IR (S/N dep.)

• Characteristics: SPIROU FTS Spectrometer Nicolet800

• Article: Quirico and Schmitt 1997a

Availability to community:

- Technical improvements/calibration (10%)
- IPAG + associated laboratories measurements (60%)
- open as facility or to specific collaborations w. funding (20%)

References:

- Baklouti, D., B. Schmitt and O. Brissaud 2008. S2O, polysulfuroxide and sulfur polymer on Io’s surface ? Icarus, 194, 647-659. doi:10.1016/j.icarus.2007.11.016

- Baklouti Donia 2006. Etude spectroscopique et chimique de la composition de la surface du satellite Io. PhD thesis, Université Joseph Fourier, Grenoble

- Beck, P., A. Garenne, E. Quirico,L. Bonal, G. Montes-Hernandez, F. Moynier, B. Schmitt 2014a. Transmission infrared spectra (2–25 µm) of carbonaceous chondrites (CI, CM, CV–CK, CR, C2 ungrouped): Mineralogy, water, and asteroidal processes. Icarus. 229, 263-277 doi:10.1016/j.icarus.2013.10.019

- Beck P., E. Quirico, A. Garenne, Q-Z Yin, L. Bonal, B. Schmitt, G. Montes-Hernandez, G. Montagnac, R. Chiriac, F. Toche 2014b. The secondary history of Sutter's Mill CM carbonaceous chondrite based on water abundance and the structure of its organic matter from two clasts. Meteoritics & Planetary Science, 49, 2064-2073 doi:10.1111/maps.12273

- Beck P., B. Schmitt, E.A. Cloutis, P. Vernazza 2015a. Low-Temperature reflectance spectra of brucite and the primitive surface of 1-Ceres? Icarus, 257, 471. doi:10.1016/j.icarus.2015.05.031

- Beck P., A. Pommerol, B. Zanda, L. Remusat, JP Lorand, C. Göpel, R. Hewins, S. Pont, E. Lewin, E. Quirico, B. Schmitt, G. Montes-Hernandez, A. Garenne, L. Bonal, O. Proux, JL Hazemann, V.C.F. Chevrier 2015b. A Noachian source region for the “Black Beauty” meteorite, and a source lithology for Mars surface hydrated dust?, Earth Planet. Sci. Letters, 427, 104-111. doi:10.1016/j.epsl.2015.06.033

- Coustenis, A., B. Schmitt, R.K. Khanna and F. Trotta 1999. Plausible condensates in Titan's stratosphere from Voyager infrared spectra. Planet. Space Sci., 47, 1305-1329 doi:10.1016/S0032-0633(99)00053-7

- Faure M., E. Quirico, A. Faure, B. Schmitt, P. Theulé, and U. Marboeuf 2015. Kinetics of hydrogen/deuterium exchanges in cometary ices. Icarus, 261, 14-30. doi:10.1016/j.icarus.2015.08.002

- Garenne, A., P. Beck, G. Montes-Hernandez, R. Chiriac, F. Toche, E. Quirico, L. Bonal, B. Schmitt 2014. The abundance and stability of “water” in type 1 and 2 carbonaceous chondrites (CI, CM and CR). Geochimica et Cosmochimica Acta, 137, 93-112 doi:10.1016/j.gca.2014.03.034

- Grundy, W., B. Schmitt, and E. Quirico 1993. The temperature dependent spectra of α and β nitrogen ice with application to Triton. Icarus 105, 254-258 doi:10.1006/icar.1993.1122

- Grundy, W., and B. Schmitt 1998. The temperature-dependent near-infrared absorption spectrum of hexagonal H2O ice. J. Geophys. Res. E, 103, 25809-25822. doi:10.1029/98JE00738

- Grundy, W., B. Schmitt, and E. Quirico 2002. The temperature-dependent spectrum of methane ice I between 0.7 and 5 µm and opportunities for near-infrared remote thermometry. Icarus, 155, 486-496. doi:10.1006/icar.2001.6726

- Merlin, F., E. Quirico, M. A. Barucci, and C. de Bergh, 2012. Methanol ice on the surface of minor bodies in the solar system. Astron. Astrophys. 544, A20, 8pp. doi:10.1051/0004-6361/201219181

- Orthous-Daunay, F.-R., E. Quirico, P. Beck, O. Brissaud, E. Dartois, T. Pino, B. Schmitt 2013. Mid-infrared study of the molecular structure variability of Insoluble Organic Matter from primitive chondrites. Icarus, 223, 534-543. doi:10.1016/j.icarus.2013.01.003

- Quirico, E., S. Douté, B. Schmitt, C. de Bergh, D.P. Cruikshank, T.C. Owen, T.R. Geballe, and T.L. Roush 1999. Composition, physical state and distribution of ices at the surface of Triton. Icarus, 139, 159-178. doi:10.1006/icar.1999.6111

- Quirico, E., B. Schmitt, R. Bini, and P.R. Salvi 1996. Spectroscopy of some ices of astrophysical interest: SO2, N2 and N2:CH4 mixtures. Planet. Space Sci. 44, 973-986. doi: 10.1016/0032-0633(96)00006-2

- Quirico, E. and B. Schmitt 1997a. Near infrared spectroscopy of simple hydrocarbons and carbon oxides diluted in solid N2 and as pure ices: implication for Triton and Pluto. Icarus 127, 354-378. doi:10.1006/icar.1996.5663

- Quirico, E. and B. Schmitt 1997b. A spectroscopic study of CO diluted in N2 ice: Applications for Triton and Pluto. Icarus 128, 181-188. doi:10.1006/icar.1997.5710]

- Quirico, E., G. Montagnac, V. Lees, P. F. McMillan, C. Szopa, G. Cernogora, J-N Rouzaud, P. Simon, J-M Bernard, P. Coll, N. Fray, B. Minard, F. Raulin, B. Reynard, B. Schmitt 2008. New experimental constraints on the composition and structure of tholins. Icarus, 198, 218-231. doi:10.1016/j.icarus.2008.07.012

- Ratajczak, A., E. Quirico, A. Faure, B. Schmitt, and C. Ceccarelli 2009. Hydrogen/deuterium spontaneous exchange in interstellar ice analogues. Astron. Astrophys., 496, L21-L24. doi:10.1051/0004-6361/200911679

- Schmitt, B., C. de Bergh, E. Lellouch, J.P. Maillard, A. Barbe, and S. Douté 1994. Identification of three absorption bands in the two micron spectrum of Io. Icarus 111, 79 105 doi:10.1006/icar.1994.1135

- Schmitt, B., E. Quirico, F. Trotta, and W. Grundy 1998. Optical properties of ices from UV to infrared. In Solar System Ices, (B. Schmitt, C. de Bergh, and M. Festou eds.) Kluwer Academic Publ., Dordrecht, Astrophys. Space Sci. Lib., Vol. 227, pp. 199-240 [ISBN: 0792349024]

- Schmitt, B., and S. Rodriguez 2003. Possible identification of local deposits of Cl2SO2 on Io from NIMS/Galileo spectra. J. Geophys. Res. E (9), 108, 5104-5122 (8-1) doi:10.1029/2002JE001988, 2003

- Trotta, F., and B. Schmitt 1996. Determination of the optical constants of solids in the mid infrared. in “The Cosmic Dust Connection”, ed. J.M. Greenberg, Kluwer Academic Publishers, NATO ASI Series C, Vol. 487, 179-184.