Critical Beamline Upgrades

Some of Diamond's existing beamlines will require upgrades as part of the programme. We have outlined some of the critical and major upgrades below, and the implications to the improvements in synchrotron science at Diamond:

B07 B16 B18 B21

Scientific aims: 

Catalysts and, more generally, new functional materials are seen as key research areas for Diamond-II. Their latest generation (size-controlled nanoparticles, zeolites, MOFs, battery/electrochemical interfaces, bio-inspired materials, etc.) are engineered at the molecular level to tailor their chemical interaction with their environments, which are gaseous or liquid by nature. The behaviour of these systems is dominated by chemical processes that occur at surfaces and interfaces and their investigation therefore requires a high level of surface sensitivity, which is provided by soft X-ray spectroscopies. By means of techniques such as XPS and NEXAFS, VerSoX investigates the electronic and chemical properties of the near-surface region in pressure ranges that vary from UHV (< 10-9 mbar) to less standard Near Ambient Pressure (NAP) conditions (> 1 bar).   

Related to the surface sensitivity of soft X-rays is the strong attenuation of both X-rays and photoelectrons in the gas phase, which is strongly energy-dependent. This directly leads to the intrinsic benefits of a large energy range and high photon flux at the sample when studying these materials under realistic conditions. Indeed, a higher photon intensity (approximately 100-fold compared to the current VerSoX source) directly facilitates the detection of dilute surface species at higher pressures which is important for many material science research areas such as heterogeneous catalysis, corrosion, thin film growth, biological systems, and the design of drug delivery systems at a molecular level, to cite a few. With a higher incident photon flux also comes a faster data acquisition and, thus, a better time resolution in the (sub-)second range. Relevant surface processes occur at many different time scales from ns (breaking of bonds) via μs-ms (e.g., adsorption, surface diffusion) and seconds (e.g., sintering) to minutes and hours (macroscopic reconstruction); any improvement in time resolution from the current minute scale will therefore provide valuable information about surface dynamic phenomena which were not accessible up to now. The available time scales will also be expanded in the other direction (days to months) by implementing a new capability of long-duration experiments, i.e., sample cells which can be transferred in and out the end station while maintaining a reaction environment. Diamond has pioneered such experiments at BL I11, and this facility will be unique amongst soft X-ray beamlines worldwide. Particular benefits are foreseen for studying the long-term behaviour of batteries and catalyst.       

The increased photon energy range, which will include both soft and tender X-rays, will increase the information depth and thus depth profiling capabilities of the beamline (up to 10 nm) and allow access to buried interfaces. The former is important to many fields ranging from heritage conservation to catalysis, the latter will benefit investigations of high-pressure or buried interface samples. Examples are energy related solid/liquid electrode/electrolyte interfaces or porous materials, such as MOF and zeolites, where the active sites are usually found within the pores several nm below the surface.   

Finally, the variable polarisation (linear and circular) afforded by the undulator will enable molecular orientations, surface chirality, magnetic properties, etc. to be determined by NEXAFS as a function of applied environmental conditions and open up the entirely new technique of resonant soft X-ray scattering to the user communities.  

Scientific aims: 

B16 is a world-leading Test beamline with exceptional flexibility, versatility, user-friendliness, and publication output. The beamline has been highly successful in helping to develop enabling optics and detector technologies by providing unique and timely test facilities to both in-house and external users. B16 also helps in the perfection of techniques and methodologies which then enable high-quality research to be performed on other beamlines. The Test beamline is in operation since Jan 2008 and has an exceptional track record. The two SAC reviews in the last 10 years rated B16 as the best Test / Optics beamline in the world. The beamline has been producing a steady flow of high-quality peer reviewed publications. 

The beamline presently covers a wide photon energy range from 4 to 45 keV and offers several operational modes that include monochromatic and white beams; and micro/ nano-focused beams. Nominally 50% of beamtime is given to external users who use B16 to pursue a mix of interesting science and technological developments. 

The main emphasis on the Test beamline has been to progress technological developments in synchrotron X-ray science. For instance, the beamline has been instrumental in developing and making major advances in three imaging techniques: 1) X-ray birefringence imaging technique (published in Science), 2) near-field X-ray speckle-based phase contrast and dark field contrast imaging (published in Scientific Reports and PRL) and 3) an imaging technique combining X-ray fluorescence and X-ray transmission through the sample to study dynamic processes (published in Scientific Reports). 

B16 has also continued to pursue significant in-house research (IHR) which directly benefits many Diamond beamlines. This has included the design and development of a new multi-lane mirror concept to rapidly vary the beam size and shape; the topographic and diffraction quality testing of I15-1 and I20 monochromator crystals; and the development of Medipix-based MERLIN and EXCALIBUR detectors among many others. The heat-exchanger of the wiggler-based I20 monochromator crystals continues to be problematic and B16 is providing valuable feedback for iterative improvement of the design. 

Another important IHR project undertaken on B16 is the development of a novel method for compensating residual slope-errors on X-ray mirrors, using refractive structures fabricated by LIGA and 3D printing processes. Excellent initial results have been obtained. The work is continuing and once the design and technology is matured, we expect this to be a significant pathway for achieving diffraction limited focusing on Diamond and other synchrotron beamlines. 

With the lattice of Diamond-II changing to a 6BA configuration, there would be no bending magnets producing hard X-rays, thereby necessitating the replacement of the source of the Test beamline with a new insertion device in the B16 mid-straight section. 

While all the existing scientific and technological uses of the Test beamline will continue to be pursued on Diamond-II, the ultra-low emittance and high brightness HPMU undulator source will enable new scientific avenues to be explored. This will include studies requiring true nano-focusing (<100nm), high coherence, and high-speed imaging (topography, absorption and phase contrast). The availability of a significantly higher flux at higher X-ray energies (up to 45 keV) will enable the Test beamline to support even broader fields, including testing and calibration of detectors and imaging at high X-ray energies. 

Just as for Diamond, new technologies for Diamond-II will require testing facilities to validate concepts and techniques and reduce risks to an operational facility. B16 Test beamline will provide this. 

Scientific aims: 

The B18 beamline is an upgrade of the B18 core EXAFS beamline. The aim of the upgrade is to ensure that the beamline is operational after the Diamond-II upgrade programme, and that it maintains the B18 main characteristics: access to a broad energy range, ease of operation, reliability and stability. In particular, it is important to maintain the fast energy changing capabilities of B18, enabling measurements of multiple edges in rapid succession. This has been critical for the success of the beamline, and particularly key for the study of processes in situ and under operation conditions.  

The higher photon flux delivered by the new B18 source will be advantageous for the study of more dilute systems, pushing the boundaries of detection limits. The higher flux will also improve the capability of the beamline to perform in situ and under operando experiments, improving the data signal-to-noise ratio maintaining the temporal resolution.   

More information on this update coming soon.