# Opportunities for Two-color Experiments at the SASE3 undulator line of the European XFEL

## TL;DR

This paper explores a cost-effective method to generate two-color X-ray pulses at the European XFEL's SASE3 beamline, enabling advanced pump-probe experiments with controllable delays.

## Contribution

Proposes a simple magnetic chicane technique for two-color pulse generation at SASE3, supported by simulations demonstrating feasibility.

## Key findings

- Feasibility of two-color pulse generation confirmed by simulations.
- Potential for enhanced X-ray pump-probe experiments at European XFEL.
- Cost-effective upgrade approach for existing XFEL infrastructure.

## Abstract

X-ray Free Electron Lasers (XFELs) have been proven to generate short and powerful radiation pulses allowing for a wide class of novel experiments. If an XFEL facility supports the generation of two X-ray pulses with different wavelengths and controllable delay, the range of possible experiments is broadened even further to include X-ray-pump/X-ray-probe applications. In this work we discuss the possibility of applying a simple and cost-effective method for producing two-color pulses at the SASE3 soft X-ray beamline of the European XFEL. The technique is based on the installation of a magnetic chicane in the baseline undulator and can be accomplished in several steps. We discuss the scientific interest of this upgrade for the Small Quantum Systems (SQS) instrument, in connection with the high-repetition rate of the European XFEL, and we provide start-to-end simulations up to the radiation focus on the sample, proving the feasibility of our concept.