Laboratory Spectra of CO2 Vibrational Modes in Planetary Ice Analogs

Laboratory spectra have shown that CO2 is a powerful diagnostic tool for analyzing infrared data from remote observations, as it has been detected on icy moons in the outer Solar System as well as dust grain surfaces in the interstellar medium (ISM). IR absorption band profiles of CO2 within ice mixtures containing H2O and CH3OH change with respect to temperature and mixture ratios. In this particular study, the CO2 asymmetric stretching mode near 4.3 m (2350 cm (exp-1)), overtone mode near 1.97 m (5080 cm (exp-1)), and the combination bands near 2.7 m (3700 cm (exp-1)), 2.8 m (3600 cm (exp-1)), and 2.02 m (4960 cm (exp -1)), are systematically observed in different mixtures with H2O and CH3OH in temperature ranges from 15K to 150 K. Additionally, some high-temperature deposits (T greater than 50 K) of H2O, CH3OH, and CO2 ice mixtures were performed. These data may then be used to interpret infrared observational data obtained from icy surfaces in the outer Solar System and beyond

Laboratory Studies of Solid Carbon Dioxide in Planetary and Interstellar Ices

Laboratory spectra have shown that CO2. is a powerful diagnostic tool for analyzing infrared data from remote observations, as it has been detected on icy moons in the outer solar system as well as dust grain surfaces in the interstellar medium. IR absorption profiles of CO2 wi thin ice mixtures containing H2O and CH30H change with respect to tem perature and mixture ratios. In this particular study, the CO2 stretch mode around 235O cm (exp -1) (4.3 rricrons) is systematically observ ed in different mixtures with H2O and CH30H in temperature ranges from 15K to 150 K, as well as vibrational modes in the near-IR such as th e combination bands near 3700 cm (exp -1) (2.7 microns) and 5080 (exp -1) (2.0 microns). Additionally, some high?temperature deposits (T > 50 K) of H2O, CH30H, and CO2 ice mixtures were performed to determine the maximum temperatures at which CO2 will deposit on the sample win dow. These data may then be used to interpret spectra obtained from remote IR observations. This research was sponsored by Oak Ridge Associ ated Universities (ORAU) through the NASA Postdoctoral Program (NPP) as well as Ames Research Center and the SETI institute who provided fa cilities and equipment

Water ice and radiation in the solar system

Infrared detection of water ice phase can reveal the temperature and radiation history of a surface. In this dissertation, I will describe and quantify the process of amorphization of crystalline ice through lab experiments and computer simulations. I will then show how these measurements can be applied to ground based observations. The amorphous phase of solid water forms at temperatures less than 130 K, and converts to crystalline ice at 135 K in an exothermic and irreversible reaction. The amorphous and crystalline phases have distinctive spectra in the infrared. However, ion irradiation of crystalline water ice in the lab makes the infrared spectrum indistinguishable from that of amorphous ice. If the process of amorphization can be quantified, the model can be applied to various planetary surfaces, using an estimate of the temperature and the radiation environment. This work sheds light on the physical processes behind amorphization. I will show that the irradiation of crystalline ice does not create the amorphous phase of ice, but produces a sample that is spectrally indistinguishable from amorphous water ice. The changes in the spectral features are caused by the breaking of OH and hydrogen bonds among other processes. The temperature dependence of this process is a function of the ability of free hydrogen and oxygen to reform the crystalline lattice

New Optical Constants of Amorphous and Crystalline H2O-ice, 3-20_m

We will present new optical constants forth amorphous and crystalline H2O-ice in the spectral range 3-20 _m. Our new measurements provide high temperature resolution for crystalline H2O-ice, 10 K intervals from 20-150 K, including temperatures relevant to Solar System ices. We have found that the shape of the 3 _m feature in amorphous H2O-ice is strongly dependant on deposition temperature and the high and low density phases of amorphous H2O-ice are not easily distinguishable. We will present methods of measuring the change in band shape with phase and temperature. We acknowledge financial support from the NASA Origins of the Solar System Program and the NASA Planetary Geology and Geophysics Program

Ion irradiation of crystalline H2O–ice: Effect on the 1.65-μm band

International audienceWe have found that 0.8 MeV proton irradiation of crystalline H2O–ice results in temperature dependent amorphization. The H2O–ice's phase was determined using the near infrared spectrum from 1.0 μm (10,000 cm−1) to 2.5 μm (4000 cm−1). In crystalline H2O–ice, the 1.65-μm (6061 cm−1) band is strong while it is nearly absent in the amorphous spectrum [Schmitt, B., Quirico, E., Trotta, F., Grundy, W.M., 1998. In: Schmitt, B., de Bergh, C., Festou, M. (Eds.), Solar System Ices. Kluwer Academic, Norwell, MA, 1998, pp. 199–240]. In this experiment, at low temperatures (9, 25, and 40 K), irradiation of crystalline H2O–ice produced the amorphous H2O–ice's spectrum. However, at 50 K, some crystalline absorptions persisted after irradiation and at 70 and 100 K the crystalline spectrum showed only slight changes after irradiation. Our results agree with previous H2O–ice irradiation studies examining the crystalline peaks near 44 and 62 μm by Moore and Hudson [Moore, M.H., Hudson, R.L., 1992. Astrophys. J. 401, 353–360] and near 3.07 μm by Strazzulla et al. [Strazzulla, G., Baratta, G.A., Leto, G., Foti, G., 1992. Europhys. Lett. 18, 517–522] and by Leto and Baratta [Leto, G., Baratta, G.A., 2003. Astron. Astrophys. 397, 7–13]. We present a method of measuring band areas to quantify the phase and radiation dose of icy Solar System surfaces

New Optical Constants for Amorphous and Crystalline H2O-ice

We have used the infrared spectra of laboratory ices to calculate the real and imaginary indices of refraction for amorphous and crystalline H2O-ice. We create H2O-ice samples in vacuum (approx. 10(exp ^-8)Torr). We measure the thickness of the sample by reflecting a He-Ne laser off of the sample and counting interference fringes as it grows and then collect transmission spectra of the samples in the wavelength range 1.25-22 micrometers. Using the ice thickness and transmission spectrum we calculate the imaginary part of the index of refraction. A Kramers-Kronig calculation is then used to calculate the real part of the index of refraction (Berland et al. 1994; Hudgins et al. 1993). These optical constants can be used to create model spectra for comparison to spectra from Solar System objects. We will summarize the differences between the amorphous and crystalline H2O-ice spectra. These include weakening of features and shifting of features to shorter wavelength in amorphous H,O-ice spectra. We will also discuss methods of using band area ratios to quickly estimate the fraction of amorphous to crystalline H2O-ice. We acknowledge financial support from the NASA Origins of the Solar System Program, the NASA Planetary Geology and Geophysics Program, and the NASA Postdoctoral Program

Ethane on Pluto and Triton

International audienceNew spectra of Pluto were obtained with the Gemini Near-Infrared Spectrometer (GNIRS) on the Gemini South 8-m telescope covering the region 1.9-2.5 µm. We have analyzed these data and two spectra of Triton with particular emphasis on a weak absorption feature detected at 2.405 μm. While this wavelength is coincident with a 13CO absorption band that is the isotopic variant of the 12CO band (2.35 μm) seen on both Pluto and Triton, our analysis, supported by new lab spectra of CO, shows that the strength of the 2.405-μm band is much too great to be attributed to any plausible abundance of 13CO. Instead, we identify this band as the 2.4045 μm absorption of pure ethane in solid form (Quirico & Schmitt Icarus 127, 354, 1997). Published models of the spectra of Triton (Quirico et al. Icarus 139, 159, 1999) and Pluto (Douté et al. Icarus 142, 421, 1999) show small variations from the data at 2.28 μm. The addition of absorption from the ethane band at 2.274 μm removes this small discrepancy. We do not see evidence for the 2.461 μm ethane band, although this is a somewhat noisy region of both spectra. Other investigators (Nakamura et al. P.A.S. Japan 52, 551, 2000) noted that Pluto's absorption bands at 2.28 and 2.32 μm are best fit with ethane, but their 2.405 μm region is discrepant with ethane. At longer wavelengths, Sasaki et al. (Ap.J. 618, L57, 2005) noted that models fit their Pluto data best when ethane was added, but they did not clearly identify ethane bands. Estimates of the abundances of ethane on Triton and Pluto suggest that this ice is deposited on relatively short time-scales by precipitation from the atmosphere, where it is produced by photochemistry (Krasnopolsky & Cruikshank JGR 100, 21271, 1995; JGR 104, 21979, 1999)

Composition of KBO (50000) Quaoar

International audienc

Composition of KBO (50000) Quaoar

International audienc