The adiabatic ionisation energy of CO₂

Abstract

The adiabatic ionisation energy $E_{\mathrm{I}}$ of CO${}_2$, corresponding to the interval between the X ${}^1{\mathrm{\Sigma }}_{\mathrm{g}}^{+}(v_1,v_2,v_3=0,0,0),J=0$ ground state of CO${}_2$ and the X${}^{+}$ ${}^2{\mathrm{\Pi }}_{\mathrm{g},3/2}(0,0,0),J^{+}=3/2$ ground state of CO${}_2^{+}$ has been determined to be $E_{\mathrm{I}}=hc\cdot 111,112.29\left(18\right)\mathrm{c}{\mathrm{m}}^{-1}$ by pulsed-field-ionisation zero-kinetic-energy photoelectron spectroscopy of a low-pressure CO${}_2$ gas sample at room temperature. The improved precision and accuracy compared to earlier values result from the use of a multipulse electric-field sequence for the selective ionisation of high Rydberg states and the use of a stationary gas sample to suppress uncertainties from Doppler shifts.

GRAPHICAL ABSTRACT

Keywords:

• PFI-ZEKE photoelectron spectroscopy
• adiabatic ionisation energy
• Rydberg states
• carbon dioxide

Acknowledgments

We dedicate this article to Timothy P. Softley and thank him for his inspiring role over many years.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported financially by the Swiss National Science Foundation (Grant No. 200020-172620) and the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Advanced Grant No. 743121).