Laser and Fourier transform spectroscopy of $^7$Li$^{88}$Sr

TL;DR

This study combines Fourier transform and laser spectroscopy to analyze the electronic and vibrational states of LiSr, providing detailed spectroscopic data and potential energy curves for key states.

Contribution

It presents new high-resolution spectroscopic data and detailed potential energy curves for LiSr's ground and excited states, including state coupling analysis.

Findings

Identification of vibrational levels up to v''=2 in the ground state.

Determination of Dunham coefficients and spin-rotation parameters.

Observation of coupling between the 2^2Σ^+ and 1^2Π states.

Abstract

LiSr was produced in a heat-pipe oven and its thermal emission spectrum around 9300 cm$^{-1}$ was recorded by a high resolution Fourier transform spectrometer. In addition, selected lines of the spectrum of deeply bound vibrational levels of the $1^2\Sigma^+$ and $2^2\Sigma^+$ states were studied using laser excitation to facilitate the assignment of the lines. The ground state could be described for $v^{\prime\prime} =$ 0 - 2, $N^{\prime\prime}$ up to 105 and the $2^2\Sigma^+$ state for $v^{\prime} = 0$ up to $N^\prime = 68$. For both states, Dunham coefficients, spin-rotation parameters and potential energy curves were evaluated. A coupling of the $2^2\Sigma^+$ state to the $1^2\Pi$ state was observed, allowing a local description with Dunham coefficients of the $1^2\Pi$ state and an approximate evaluation of the coupling strength.