Spectroscopic Determination of the Phase Composition and Temperature of Nitrogen Ice on Triton

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Science  06 Aug 1993:
Vol. 261, Issue 5122, pp. 751-754
DOI: 10.1126/science.261.5122.751


Laboratory spectra of the first overtone band (2.1480 micrometers, 4655.4 reciprocal centimeters) of solid nitrogen show additional structure at 2.1618 micrometers (4625.8 reciprocal centimeters) over a limited temperature range. The spectrum of Neptune's satellite Triton shows the nitrogen overtone band as well as the temperature-sensitive component. The temperature dependence of this band may be used in conjunction with ground-based observations of Triton as an independent means of determining the temperature of surface deposits of nitrogen ice. The surface temperature of Triton is found to be 38.0+2.0–1.0 K, in agreement with previous temperature estimates and measurements. There is no spectral evidenceforthe presence of α-nitrogen on Triton's surface, indicating thatthere is less than 10 percent carbon monoxide in solid solution with the nitrogen on the surface.