The B-X and C-X band systems of CuCl revisited: A laser-induced fluorescence study in 465-490 nm

TL;DR

This study revisits the B-X and C-X band systems of CuCl using laser-induced fluorescence spectroscopy, revealing mixed singlet-triplet states and providing detailed rotational and lifetime analyses.

Contribution

It provides new spectroscopic data and insights into the singlet-triplet mixing in CuCl's excited states, clarifying previous ambiguities.

Findings

Identification of singlet-to-singlet transition nature.

Observation of mixed singlet-triplet states with microsecond lifetimes.

Detection of two excited states possibly contaminated by triplet interactions.

Abstract

We have reinvestigated the B-X and C-X band systems of CuCl by recording the laser-induced fluorescence excitation spectra in 20400-21800 cm^{-1}. The rotational analyses in Hund's case (a) revealed unambiguously a singlet-to-singlet transition nature. The measured lifetimes of a few microseconds seem too long for singlets and too short for triplets, which we think is actually in favor of a picture of singlet ({1}^Pi and {1}^Sigma^{+})-triplet ({3}^Pi_{0,1,2}) mixed states in the B and C band systems of CuCl. The two excited states we observed in our spectra may be the singlets that have been strongly "contaminated" by their triplet neighbors.