UV spectra of iron-doped carbon clusters FeC_n n = 3-6

TL;DR

This study measures the UV electronic spectra of iron-doped carbon clusters FeC$_n$ (n=3-6), compares experimental rotational profiles with theoretical models, and provides insights into their geometries and electronic transitions.

Contribution

It presents the first experimental UV spectra of FeC$_n$ clusters and compares them with theoretical predictions to elucidate their structures and electronic states.

Findings

FeC$_3$ has a planar fan-like structure.

FeC$_4$ shows a shorter Fe-C distance and a different electronic transition.

FeC$_5$ appears non-linear despite predictions.

Abstract

Electronic transitions of jet-cooled FeC$_n$ clusters ($n = 3 - 6$) were measured between 230 and 300 nm by a mass-resolved 1+1 resonant two-photon ionization technique. Rotational profiles were simulated based on previous calculations of ground state geometries and compared to experimental observations. Reasonable agreement is found for the planar fan-like structure of FeC$_3$. The FeC$_4$ data indicate a shorter distance between the Fe atom and the bent C$_4$ unit of the fan. The transitions are suggested to be $^{3}$A$_{2} \leftarrow ^{3}$B$_{1}$ for FeC$_3$ and $^{5}$A$_{1} \leftarrow ^{5}$A$_{1}$ for FeC$_4$. In contrast to the predicted C$_{\infty \text{v}}$ geometry, non-linear FeC$_5$ is apparently observed. Line width broadening prevents analysis of the FeC$_6$ spectrum.