Two-photon Doppler-free ultraviolet laser spectroscopy on sulphur atoms

TL;DR

This paper presents a high-precision two-photon ultraviolet laser spectroscopy study of sulphur atoms, improving level separation measurements and determining isotope shifts with Doppler-free and collision-free conditions.

Contribution

It introduces a novel two-photon excitation scheme for sulphur atoms that enhances measurement accuracy and provides new data on level separations and isotope shifts.

Findings

Improved accuracy in sulphur atomic level separations.

Precise measurement of the $^{3}$P$_{2}$ - $^{3}$P$_{1}$ ground state splitting.

Determination of isotope shifts between $^{34}$S and $^{32}$S.

Abstract

The $3p^{4}$ $^{3}$P$_{J}$ - $3p^{3}4p$ $^{3}$P$_{J}$ transition in the sulphur atom is investigated in a precision two-photon excitation scheme under Doppler-free and collision-free circumstances yielding an absolute accuracy of 0.0009 cm$^{-1}$, using a narrowband pulsed laser. This verifies and improves the level separations between amply studied odd parity levels with even parity levels in S I. An improved value for the $^{3}$P$_{2}$ - $^{3}$P$_{1}$ ground state fine structure splitting is determined at $396.0564$ (7) cm$^{-1}$. A $^{34}$S - $^{32}$S atomic isotope shift was measured from combining time-of-flight mass spectrometry with laser spectroscopy.