Cavity Ring Down Spectroscopy Measurements for High-Overtone Vibrational Bands of HC₃N

Abstract

Overtone (5ν1 and 6ν1) and combination (4ν1 + ν3 and 4ν1 + ν2) vibrational bands of gaseous HC3N, located in the visible range (14,600-15,800 and 17,400-18,600 cm(-1)), were investigated by cavity ring-down absorption spectroscopy. The 5ν1 + ν3 and 5ν1 + ν2 combinations as well as the 6ν1 + ν5 - ν5 hot overtone band have also been identified, on the basis of previous overtone assignments. Absolute integrated intensity values and the ensuing oscillator strengths have been measured here for the first time; f values are typically confined between 4 × 10(-12) and 7 × 10(-11). For the even weaker 5ν1 + ν2 combination band, the oscillator strength was estimated as 9 × 10(-13). The values concerning CH-stretch overtones (nν1) are similar to those found in the literature for HCN and C2H2, the molecules with sp-hybridized carbon atoms. Data presented here may prove useful for studying the photochemistry triggered with visible or near-IR radiation within the atmospheres of certain Solar System bodies, including Titan.

Detectable Abundance of Cyanoacetylene (HC$_3$N) Predicted on Reduced Nitrogen-Rich Super-Earth Atmospheres

“…There existed no comprehensive IR line list for HC 3 N applicable for a broad range of temperatures. The experimental and theoretical information is rather scarce for HC 3 N, especially in IR, only for the room temperature (Bénilan et al 2006;Jolly et al 2007;Douin et al 2015;Bizzocchi et al 2017;Jiang et al 2021). For this study, we have combined spectroscopic data available for HC 3 N in the literature to construct a line list as a best estimate of the opacity of HC 3 N in IR.…”

“…Experimentally, the IR intensities of HC 3 N was studied in Bénilan et al (2006); Douin et al (2015). High-resolution spectroscopic analyses were reported by Bizzocchi et al (2017); Jiang et al (2021).…”