First laboratory detection of vibration-rotation transitions of CH$^+$ and $^{13}$CH$^+$ and improved measurement of their rotational transition frequencies

TL;DR

This paper reports the first laboratory detection of vibration-rotation transitions of CH$^+$ and $^{13}$CH$^+$ ions, using cryogenic helium attachment, and provides improved measurements of their rotational frequencies.

Contribution

It presents the first laboratory observation of fundamental vibrational transitions of CH$^+$ and $^{13}$CH$^+$, and refines their rotational transition frequencies.

Findings

First detection of vibrational transitions in CH$^+$ and $^{13}$CH$^+$

Improved accuracy of rotational transition frequencies

Enhanced understanding of ion spectroscopy at cryogenic temperatures

Abstract

The long-searched C-H stretches of the fundamental ions CH$^+$ and $^{13}$CH$^+$ have been observed for the first time in the laboratory. For this, the state-dependent attachment of He atoms to these ions at cryogenic temperatures has been exploited to obtain high-resolution rovibrational data. In addition, the lowest rotational transitions of CH$^+$, $^{13}$CH$^+$ and CD$^+$ have been revisited and their rest frequency values improved substantially.