Lifetime of the A(v'=0) state and Franck-Condon factor of the A-X(0-0) transition of CaF measured by the saturation of laser-induced fluorescence

TL;DR

This paper presents a method to measure molecular radiative decay properties using laser-induced fluorescence saturation, applied to CaF to determine its state lifetime, Franck-Condon factor, and hyperfine interval.

Contribution

The study introduces a novel approach to determine molecular decay parameters through fluorescence saturation and power broadening analysis.

Findings

Measured the lifetime of CaF's A(v'=0) state as 19.2 ns

Determined the Franck-Condon factor for CaF as 0.987

Estimated the hyperfine interval in A(v'=0) as 4.8 MHz

Abstract

We describe a method for determining the radiative decay properties of a molecule by studying the saturation of laser-induced fluorescence and the associated power broadening of spectral lines. The fluorescence saturates because the molecules decay to states that are not resonant with the laser. The amplitudes and widths of two hyperfine components of a spectral line are measured over a range of laser intensities and the results compared to a model of the laser-molecule interaction. Using this method we measure the lifetime of the A(v'=0) state of CaF to be tau=19.2 \pm 0.7 ns, and the Franck-Condon factor for the transition to the X(v=0) state to be Z=0.987 (+0.013 || -0.019). In addition, our analysis provides a measure of the hyperfine interval in the lowest-lying state of A(v'=0), Delta_e=4.8 \pm 1.1 MHz.