Figure 6.

Matrix IR absorption spectra demonstrating the presence of ethylene $({\text{H}}_2\text{C}=\text{C}{\text{H}}_2)$ following the thermal cracking of ethanethiol in a pulsed reactor (0.01% CH₃CH₂SH/Ar). The blue trace is that of the buffer gas Ar at 1400 K, the black trace is CH₃CH₂SH at room temperature, the green trace is a spectrum of pure ethylene at 300 K, and the red trace results from heating CH₃CH₂SH to 1300 K. The IR features at 1439 and 947 cm⁻¹ in the spectrum at 1300 K clearly belong to ν₁₂ and ν₇ of ethylene.