The observation of hot bands in the 288nm system of the FeCl2 radical

The 288 nm band system of FeCl2 has been recorded with a sample produced in a warmed, free-jet expansion at moderately high resolution (with a linewidth of 0.28 cm-1). Under these conditions, several hot bands are observed involving excitation of the symmetric and anti-symmetric stretching vibrations. The wavenumbers determined as a result for FeCl2 in its ground 5?g,4 state are View the MathML source and View the MathML source. No hot, sequence bands in the bending vibration View the MathML source were observed. The most likely explanation is that the wavenumber for ?2 is essentially the same in both the electronic states involved (88 cm-1). Additional strong hot bands are observed that are unrelated to the previously assigned electronic transitions; they appear to emanate from a low-lying electronic state of FeCl2.