Optical absorption spectrum reveals gaseous chlorine in anti-resonant hollow core fibres

TL;DR

This study discovers gaseous chlorine in hollow core fibres through ultraviolet spectral attenuation, showing how atmospheric exposure affects fibre transmission and revealing chlorine's presence via absorption spectra.

Contribution

The paper demonstrates that gaseous chlorine can be detected in hollow core fibres using optical absorption spectra, providing insights into gas-fibre interactions and contamination.

Findings

Chlorine causes spectral attenuation in UV light within fibres.

Loss dissipates as chlorine reacts or escapes over time.

Initial chlorine concentration measured at 0.45 μmol/cm³.

Abstract

We have observed unexpected spectral attenuation of ultraviolet light in freshly drawn hollow core optical fibres. When the fibre ends are left open to atmosphere, this loss feature dissipates over time. The loss matches the absorption spectrum of gaseous (molecular) chlorine and, given enough time, the transmission spectrum of the fibre recovers to that expected from the morphological structure of the fibre. Our measurements indicate an initial chlorine concentration of 0.45 $\mu$ mol/cm$^{3}$ in the hollow core, equivalent to 1.1 mol% Cl$_{2}$ at atmospheric pressure.