Gas-Phase Optical Spectra of the Indenyl Radical and Its Quantitative Detection in a Jet-Stirred Reactor

Abstract

Resonance-stabilized radicals (RSRs), such as the indenyl radical (C 9 H 7 ), are proposed to be initiator radicals in soot inception and growth in hydrocarbon combustion processes, but spectroscopic data for many RSRs are still lacking. In this work, the gas-phase optical absorption spectra of the B ̃2A 2 −X ̃2A 2 electronic transition of indenyl were identified in a supersonic indene/argon plasma jet. Spectroscopic parameters, including the transition energy, rotational constants, and upper-state lifetime broadening, were obtained from analysis of the experimental spectra. The results were readily applied to the quantitative detection of indenyl produced from high-temperature reactions in a jet-stirred reactor. This study now makes indenyl optically accessible in further reaction kinetics studies and in situ spectroscopic diagnostics of hydrocarbon combustion processes.

Cyanocyclopentadiene-Annulated Polycyclic Aromatic Radical Anions: Predicted Negative Ion Photoelectron Spectra and Singlet–Triplet Energies of Cyanoindene and Cyanofluorene Radical Anions

“…83 It is therefore reasonable to approach the S 0 and T 1 vibrational analysis in CNI by inferring to the widely studied low-lying electronic states in bare indene 35,40,41,82 and indenyl radical. 24,28,84 The tabulated calculated harmonic vibrational frequencies of the radical anion S 0 and T 1 states in all the CNI isomers can be found in the Supporting Information (Tables S19−S25). A comparison between Gaussian 09 and Gaussian 16 outputs for 4-CNI and 7-CNI isomers can also be found in Tables S31−S33.…”

Gas-phase formation of the resonantly stabilized 1-indenyl (C 9 H 7 • ) radical in the interstellar medium

“…However, whereas molecular beam experiments ( 22 , 23 ) and astrochemical modeling ( 17 , 18 ) provided compelling evidence on the formation of the simplest RSFR in TMC-1, propargyl (C 3 H 3 • ), via the bimolecular reaction of atomic carbon [C( 3 P)] with ethylene (C 2 H 4 ), reaction pathways to more complex RSFRs are largely unknown ( 24 ). This knowledge is of particular importance for the 1-indenyl (C 9 H 7 • ) radical ( 25 ). As a prototype of an aromatic and RSFR, the bicyclic, fused C5-C6 species represents the key building block of nonplanar PAHs such as corannulene (C 20 H 10 ), nanobowls (C 40 H 10 ), and fullerenes (C 60 and C 70 ) (fig.…”

“…) radical (25). As a prototype of an aromatic and RSFR, the bicyclic, fused C5-C6 species represents the key building block of nonplanar PAHs such as corannulene (C 20 H 10 ), nanobowls (C 40 H 10 ), and fullerenes (C 60 and C 70 ) (fig.…”