Publications | Diamond News Autumn 2009

Diamond’s second spectroscopy beamline is on its way

Now well into its third year of operation, the Diamond synchrotron continues to grow as more and more beamlines come online. One of the upcoming Phase II experimental stations is I20, a two-branch X-ray Spectroscopy beamline which will have applications in a wide range of scientific fields; including chemistry, environmental and materials sciences and biology. Sofia Diaz-Moreno is Principal Beamline Scientist for I20.

Each of I20’s two branches is served by a wiggler insertion device within the same straight section of the machine. The first branch to go into operation will be the scanning line, which will be used for highresolution spectroscopy experiments. Key to its unique setup is a fourbounce monochromator which should guarantee the long term spectral reproducibility and stability of the beamline. These characteristics, together with the high flux and the continuous energy spectrum delivered by the wiggler source, will make this branch particularly suited for the study of samples where the photoabsorbing atomic site is present at low concentration or embedded in a highly absorbing environment.

Deflecting and collimating mirrors installed in the optics hutch of I20

The second branch is a dispersive spectrometer that will enable scientists to carry out time-resolved measurements to study fast structural changes in species present in processes in real time and under realistic conditions. Timescales ranging from seconds all the way to milliseconds or even microseconds will be accessible. This is the selection of a broad band of energies, and a spatially resolved xstrip detector developed for I20 with a readout time of only 10 microseconds.

“This branch of the beamline will be particularly useful for the study of catalytic processes, both in heterogeneous and homogeneous media,” says Dr Diaz-Moreno. “Catalysts are often present in low concentration and suffer rapid structural transformation under rapidly changing environmental conditions, such as temperature of the reaction, or composition and flow rates of gasses. The energy dispersive configuration of this branch will enable researchers to follow these rapid reactions, and study the electronic and structural changes of the catalytic sites. This will help in the design of more efficient and selective catalysts.”

The flexibility and high energy resolution of the scanning branch, combined with the speed of the dispersive branch’s detector, and the fact that experiments can take place on each branch simultaneously, make I20 a unique beamline that is eagerly awaited by the spectroscopy community.

stations – I20, I18, the existing Phase I Microfocus Spectroscopy beamline, and B18, the upcoming Phase II Core Extended X-ray Absorption Fine Structure beamline (EXAFS) – have been designed in a similar way to enable users to work on whichever beamline suits their needs without having to learn new methods and processes.

With the installation phase of I20 almost complete, first light to the beamline is expected in the autumn of this year. Dr Diaz-Moreno concludes, “It’s a very challenging project which takes a huge team effort so I am grateful to have such a hardworking and talented group of scientists, engineers and technicians working with me to achieve the successful completion and operation of I20. I look forward to welcoming first users early next year.”

The I20 beamline team

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