Rotational Rest Frequencies for FeN ( X ² _i ) and Revised Spectroscopic Constants for FeC ( X ³ _i )

Abstract

The pure rotational spectrum of FeN in its X 2 D i ground state has been recorded using millimeter-wave direct absorption techniques in the range 198-525 GHz. New measurements have also been carried out for FeC (X 3 D i ), in particular of the fine-structure component and the 54 FeC isotopomer. These molecules were created by Q p 1 the reaction of iron vapor with either CH 4 (FeC) or N 2 (FeN) in a DC discharge. Eight rotational transitions were recorded for FeN in its lowest-lying spin component, , and multiple transitions were measured for FeC Q p 5/2 in all three of its spin-orbit ladders, as well as for . These data have been analyzed, and precise 54 FeC (Q p 3) spectroscopic constants for both radicals have been determined. The fine structure in FeC was found to exhibit an irregular pattern, indicating that higher order spin-orbit perturbations are occurring in this molecule. Although only one spin component was observed for FeN, the bond length established from the data is consistent Q p 5/2 with a 2 D ground state, as indicated by theory. Fe-bearing species are relevant to many astrophysical topics, including astrochemistry, dust grains composition, nucleosynthesis, and mass loss from asymptotic giant branch stars.

The pure rotational spectrum of TiS (X3Δr) at submillimeter wavelengths

“…1). As found in the X 3 D state of FeC [18], the X = 2 line of TiS appears to be shifted to higher frequency relative to the other two components. This effect may be the result of the nearby isoconfigurational a 1 D state.…”

Millimeter-wave rotational spectroscopy of FeCN (X 4Δi) and FeNC (X 6Δi): Determining the lowest energy isomer

“…Searches for FeNC had been attempted by the Ziurys group using Broida oven synthesis methods, as employed for species such as FeC and FeN, 26 for several years prior to this work. Use of an ac discharge with Fe(CO) 5 proved to be a major factor in the success of the project.…”

Millimeter-wave spectroscopy of CrC (X3Σ−) and CrCCH (X̃ 6Σ+): Examining the chromium-carbon bond

“…The bond distance in CrC is comparable to that in NiC, which has r 0 = 1.6308 Å 16 -both of which are larger than those in FeC (1.5931 Å) and CoC (1.5612 Å). 15,16 CrC is thought to have an electron configuration of 8σ 2 3π 4 1δ 2 , with the 8σ and 3π orbitals creating a triple bond. 25 NiC is also thought to have a triple bond and an 8σ 2 9σ 2 3π 4 1δ 4 configuration, with the additional 4 electrons filling the non-bonding 1δ and 9σ orbitals.…”

“…[10][11][12][13][14] Pure rotational data have been recorded for FeC, CoC, and NiC as well. 15,16 These studies have demonstrated that the ground states of these molecules are 3 ∆, 2 Σ + , 1 Σ + , 2 ∆, and 3 Σ + , respectively. For the metal monoacetylides, CuCCH and ZnCCH have been characterized using pure rotational spectroscopy, 17,18 and recently NiCCH and CuCCH have been studied in the optical regime.…”