Inhouse diffraction experiment
Single-crystal X-ray diffraction can be successfully applied for in-depth studies of the structural transformations which involve symmetry breaking, aperiodicity or diffuse scattering. In our X-ray diffraction laboratory we use this technique for monitoring such transformations under external stimuli, i.e. temperature and light.
Our X-ray laboratory is equipped with two single-crystal X-ray diffractometers with 4-circle Kappa geometry goniometer, namely:
- Xcalibur3 with Sapphire3 CCD detector and Enhance molybdenum source of Oxford Diffraction (currently Rigaku Oxford Diffraction). It is fitted with an optical set-up coupled with a series of cw laser diodes covering wide spectrum of wavelengths from UV to IR range which allows detailed structural studies of the light induced metastable states in a single-crystal-to-single-crystal manner, i.e. by so-called photocrystallography.
- SuperNova with high sensitive EosS2 CCD detector and microfocus copper source of Agilent Technologies (currently Rigaku Oxford Diffraction).
Two diffractometers can be fitted with Oxford Cryosystem liquid nitrogen cooling apparatus. This includes Oxford 800Plus series Cryostream device which allows for measurements in the temperature range from 80 to 500K. Thanks to liquid helium Oxford Diffraction Helijet Cryostream the measurements at around 10-20K are also possible.
Inhouse optical spectroscopy laboratory
In time resolved experiments, a first pump pulse excites a sample and a second one probes its state to follow the dynamics of a photoinduced transformation. The lab has in proper synchronized and amplified femtosecond laser sources which are associated to optical parametric amplifiers and sum frequencies generator. We are so able to pump and probe materials from 260 nm to 20 µm, which covers from the electronic to the vibrational level excitation domain and low gap insulator. The dynamic of the different degrees of freedom can be spanned over ten temporal decades, from the 10s femtoseconds scale to the milliseconde one. These experiments are performed in a nitrogen jet cryostat environment where the temperature can be controlled from 80 to 400 K.
Experiments at large facilities
While short yet bright pulses of light from infrared to UV can be generated in a laboratory setup (as shown above), equivalent pulses can only be generated at large facilities. In particular our activity has centered around Synchrotrons and X-ray Free Electron Lasers.
Synchrotrons delivers tunable short pulses of ~100 ps duration. Some experimental station (ID9 at ESRF, Grenoble and Biocars at APS, Chicago) are devoted to time resolved experiments. Recently XFELs have been built delivering shorted (~ tens of fs) and brighter x-ray pulses. Our group has led several experiment at such facilities. Our group is also involved in several experimental campaigns at equilibrium ranging from high resolution diffraction (Cristal, Soleil) and Diffuse Scattering (BM01, ESRF) to inelastic X-ray scattering (ID28, ESRF).
Achieving few-femtosecond time-sorting at Hard X-ray Free Electron Lasers
M. Harmand, R. Coffee, M.R. Bionta, M. Chollet, D. French, D.M. Fritz, H.T. Lemke, N. Medvedev, B. Ziaja, S. Toleikis, M. Cammarata
Nature Photonics 7: 3138-3146 (2013);
A single-shot transmissive spectrometer for hard x-ray free electron lasers
Diling Zhu, Marco Cammarata, Jan M Feldkamp, David M Fritz, Jerome B Hastings, Sooheyong Lee, Henrik T Lemke, Aymeric Robert, James L Turner, Yiping Feng
Applied Physics Letters 101 (3), 034103
The X-ray pump–probe instrument at the linac coherent light source
Matthieu Chollet, Roberto Alonso-Mori, Marco Cammarata, Daniel Damiani, Jim Defever, James T Delor, Yiping Feng, James M Glownia, J Brian Langton, Silke Nelson, Kelley Ramsey, Aymeric Robert, Marcin Sikorski, Sanghoon Song, Daniel Stefanescu, Venkat Srinivasan, Diling Zhu, Henrik T Lemke, David M Fritz
Journal of synchrotron radiation 22 (3), 503-507