October 2022
Butadiynylformyl radical

The linear carbon chain butadiynylformyl radical (HC5O) was detected by McGuire and co-workers toward TMC-1 using the Green Bank Telescope, as reported in 2017. While the detection is based on a single rotational transition, it includes the four lines that arise from the hyperfine splitting associated with state of the molecule. As a 2Π state, the ground state of HC5O splits into two levels, which is known as fine structure. The spectroscopic constants measured by Mohammed and co-workers were used for the detection of HC5O. They were able to measure the constants for the 2Π1/2 state without also generating the spectrum of the 2Π3/2 state due to the very cold beam of molecules they were able to form. The detection of HC5O toward TMC-1 was confirmed in 2021 by Cernicharo et al., who observed a total of 14 rotational transitions.

Researcher Links
BA McGuire
AM Burkhardt
CN Shingledecker
SV Kalenskii
E Herbst
AJ Remijan
MC McCarthy

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