# Time-resolved observation of interatomic Coulombic decay induced by two-photon double excitation of Ne$_{2}$

## TL;DR

This study experimentally observes two-photon doubly-excited states in neon dimers using free-electron laser pulses, revealing their ultrafast decay dynamics and confirming theoretical predictions.

## Contribution

It is the first experimental identification of two-photon doubly-excited states in Ne$_2$ and their decay rates using time-resolved measurements.

## Key findings

- Doubly-excited states have lifetimes of approximately 390 fs and less than 150 fs.
- Ultrafast interatomic Coulombic decay predominantly produces singly-ionized dimers.
- Experimental results agree with ab initio quantum mechanical calculations.

## Abstract

The hitherto unexplored two-photon doubly-excited states [Ne$^{*}$($2p^{-1}3s$)]$_{2}$ were experimentally identified using the seeded, fully coherent, intense extreme ultraviolet free-electron laser FERMI. These states undergo ultrafast interatomic Coulombic decay (ICD) which predominantly produces singly-ionized dimers. In order to obtain the rate of ICD, the resulting yield of Ne$_{2}^{+}$ ions was recorded as a function of delay between the XUV pump and UV probe laser pulses. The extracted lifetimes of the long-lived doubly-excited states, 390 (-130 / +450} fs, and of the short-lived ones, less than 150~fs, are in good agreement with \emph{ab initio} quantum mechanical calculations.