Infrared spectroscopy of crystalline and amorphous diacetylene (C_4H_2) and implications for Titan's atmospheric composition

摘要

New laboratory spectra of crystalline and amorphous diacetylene ice have been recorded in the range of 7000-500 cm~(-1) (1.4-20 μm) to aid in the identification of solid diacetylene on Saturn's moon Titan. We have established that amorphous diacetylene ice is stable only at temperatures less than 70 ±1 K. With respect to observations on Titan, the best approach would be to utilize future space-based telescopes to search for the v_4 (3277/3271 cm~(-1)) in absorption against the reflected light from the sun and the slightly weaker v_8 absorption bands (676/661 cm~(-1)) in absorption against the continuum emission.