Leak-out Spectroscopy, a universal method of action spectroscopy in cold ion traps

TL;DR

Leak-out spectroscopy (LOS) is a new, highly sensitive method for action spectroscopy in cold ion traps that detects ions by their leakage after excitation, enabling high-resolution analysis and isomer separation.

Contribution

This paper introduces leak-out spectroscopy (LOS), a universal and sensitive method for action spectroscopy in ion traps, demonstrated on C3H+ ions for the first time.

Findings

Successfully recorded the rotationally resolved spectrum of C3H+

Demonstrated the method's ability to analyze trap content and isomer ratios

Showed LOS's potential for preparing pure samples of isomers

Abstract

A novel method of spectroscopy in ion traps termed leak-out spectroscopy (LOS) is presented. Here, mass selected, cold ions are excited by an infrared laser. In a subsequent collision with a neutral buffer gas particle their internal energy is then transferred to kinetic energy. As a result, these ions leak out from the ion trap and are detected. The LOS scheme is generally applicable, very sensitive and close to background free when operated at low temperature. The potential of this method is demonstrated and characterized here for the first time by recording the rotationally resolved spectrum of the C-H stretching vibration $\nu_1$ of linear C$_3$H$^+$. Besides performing high-resolution spectroscopy, this method opens up the way for analyzing the composition of trap content, e.g., determining isomer ratios, by selectively expelling isomers or other isobaric ions from the trap. Likewise, LOS can be used to prepare clean samples of structural and nuclear spin isomers.