Experimental Technique

The Resonant Coherent Scattering (RCS) beamline applies several X-ray scattering techniques to study the fine structure and molecular dynamics of a large variety of samples, including functional organic films, photo resists, liquid crystals, nanoparticle colloids, bio-macromolecules, and quantum materials. Resonant X-ray scattering in the soft & tender X-ray regime enables studies of heterogenies structures with high chemical and orientational sensitivity for a broad range of elements. X-ray photon correlation combined with resonant edges probes molecular dynamics of specific segments in the samples. Resonant elastic X-ray scattering combined with variable polarization, low temperature, and high magnetic field enables the structure determination of magnetic and superconducting materials under various conditions.

Beamline optics

Overview

The beamline is sourced by an elliptically polarizing undulator (EPU42) covering the photon energy range of 250-4000 eV. CM1 deflects the beam in the horizontal plane and focuses the beam in the vertical plane. The monochromator consists a plane mirror PM2 and 2 different VLS gratings, enabling high transmission both in the soft and tender X-ray regime. Slit2 selects the desired X-ray bandwidth. In Branch A, a horizontal focusing mirror (KBH4A or KBH4B) deflects and focuses the beam in the horizontal direction. Subsequently, the plane mirror (PM5) and vertical focusing mirror (KBV6A or KBV6B) focus and deliver the beam to the soft X-ray scattering (SoXS) or the tender X-ray scattering (TeXS) endstations. In Branch B, a toroidal mirror (TM7) focuses the X-ray in both directions to the quantum-materials resonant elastic X-ray scattering (QM-REXS) endstation is located.  

Key Performance

Experimental Endstation

Branch A: SoXS and TeXS

Overview

Branch A consists of two endstations, soft X-ray scattering (SoXS) and tender X-ray scattering (TeXS). A common vacuum chamber is shared by the two endstations, which also houses two front X-ray detectors. The scattering signal can be collected either by the front detectors or by the back detector. The long vacuum flight tube provides low air scattering and long sample-detector distance of about 10 m. In the middle of the flight tube, an additional chamber can be mounted to perform ambient-pressure scattering experiments. At the end of the flight tube, tender X-ray scattering images from the samples either chambers are collected by the back detector, which is a counting detector suitable for tender X-rays.

Key Performance

Branch B: QM-REXS

Overview

Branch B is the Resonant Elastic X-ray Scattering (REXS) station for quantum materials, including three main sections of the front-end optical path, the testing section, and the sample transfer unit. To ensure accurate optical alignment for the desired diffraction peaks, the sample stage provides 6-axis alignment.

There is a magnetically shielded gold mesh for beam intensity monitoring. A superconducting magnet is introduced to realize the scattering measurements at the magnetic field up to 5T with the diffraction angle of 0~140°. 

I. Load-lock

A irradiation lamp for heating and degassing.

II. Sample Transfer Chamber

up to 6 samples can be loaded (flag-type sample plate).

An xy-mini translation stage for smooth and accurate movement.

The vacuum flexible bellows for fine-tuning the sample orientation.

III. Experimental Chamber

A 4K×4K CCD detector (Greateyes) with a photodiode and channel electron multiplier.

6-axis sample alignment.  

Key Performance

Science

Scope 1 (Resonant scattering)

Resonant scattering is a powerful technique to probe complex molecular structures, with the advantage of selective resonant enhancement for elements/chemical bonds and orientations. It is particularly suitable for studying heterogeneous molecular structures in functional polymers, self-assemble systems, nanoparticle-polymer mixtures, etc. BL07 provides multiple resonant edges (from Carbon to Calcium) and variable polarizations (linear and circular), providing even more possibilities for this widely-used technique.

Scope 2 (XPCS)

XPCS is an emerging technique to probe various forms of dynamics, such as diffusion and rotation of colloidal nanoparticles, dynamics of polymer segments, diffusion of biomacromolecules and their aggregates, fluctuation of superlattice structures in quantum materials, etc. The soft and tender X-ray regime of BL07 provide both high coherence and multiple resonant edges, such that heterogeneous dynamics inside the materials can be highlighted by performing XPCS at resonant energies.

Scope 3 （REXS）

The Resonant Elastic X-ray Scattering Station for Quantum Materials is key technique to investigate the superconducting mechanisms especially high-temperature superconductors—including copper-based, iron-based, and nickel-based systems—encompassing phenomena such as antiferromagnetic order, charge density waves, and orbital order. Unveiling microscopic superconducting mechanism of high-temperature superconductors is still a major scientific challenge in the field of condensed matter physics. Meanwhile, this technique can also be employed to investigate structures such as buried interfacial magnetism, domain wall chirality in topological ferromagnets and ferroelectric thin films. This technique is essential for the development, operational testing, and performance enhancement of next-generation spintronic devices.

People

Useful Link

Related beamlines:

RSoXS

https://www.nsrl.ustc.edu.cn/10954/list.htm

https://www.bnl.gov/nsls2/beamlines/publications.php?q=7-ID-1

https://als.lbl.gov/beamlines/12-0-2/

XPCS

https://als.lbl.gov/beamlines/7-0-1-1/

https://als.lbl.gov/beamlines/11-0-1-2/

https://www.bnl.gov/nsls2/beamlines/beamline.php?r=23-ID-1

QM-REXS

https://www.helmholtz-berlin.de/pubbin/igama_output?modus=einzel&sprache=en&gid=2368&typoid=79864

https://photon-science.desy.de/facilities/petra_iii/beamlines/p04_xuv_beamline

http://e-ssrf.sari.ac.cn/beamlines_2024/sr_72267/beamline_maps/bl20u2/xzjs/