The double minimum E(3)$^1\Sigma^{+}_{\mathrm{u}}$ state in Cs$_2$

TL;DR

This paper investigates the double minimum E(3)^1Σ_u^+ state in caesium dimer by analyzing spectral data, constructing a potential energy curve, and discussing data limitations regarding the outer well.

Contribution

It provides a detailed potential energy curve for the E(3)^1Σ_u^+ state using spectral analysis and advanced computational methods, addressing data gaps in the outer well.

Findings

Identified 6727 rotationally resolved transitions.

Constructed a potential energy curve matching observed energies.

Discussed the ambiguity due to lack of outer well data.

Abstract

The double minimum E$^1\Sigma^{+}_{\mathrm{u}}$ state in caesium dimer was investigated by analysing spectra of the E$^1\Sigma^{+}_{\mathrm{u}}$ $\leftarrow$ X$^1\Sigma^{+}_{\mathrm{g}}$ band system, simplified by polarisation labelling. A total of 6727 rotationally resolved transitions to levels situated in the inner well and above the internal barrier were identified and a potential energy curve allowing to reproduce their energies was constructed using the Fourier grid Hamiltonian and inverted perturbation approach methods. The unambiguousness of the potential curve in view of lack of data related to levels located in the outer well is discussed.