Computational research at SUNCAT is performed using our own computer cluster which is physically located at SLAC and additional computing resources that we have access to. Experiments are performed at SLAC and Stanford Campus.
Experimental facilities
At SLAC we have access to X-ray facilities such as SSRL and LCLS. Many of the experiments carried out by Suncat researchers also heavily rely on the Stanford Nanocharacterization Laboratory. Besides these world leading facilities and the facilities in the individual research groups of the collaborating experimentalists, Suncat has some in-house catalyst synthesis and testing facilities such as an ALD and a high temperature reactor.
LCLSPowered by one-third of SLAC's 2-mile-long linear accelerator, LCLS is the world's first hard X-ray free-electron laser. It produces up to 120 X-ray pulses a second, each only a few millionths of a billionth of a second long yet more than a billion times brighter than any previous source.
Scientists use LCLS to take stop-action pictures of atoms and molecules in motion, shedding light on the fundamental processes of chemistry, technology and life itself.
Working with a suite of six LCLS instruments, researchers are developing new ways to obtain meaningful images of samples sprayed or squirted into the path of the X-ray laser beam, and creating X-ray holograms that record magnetic orientation within materials with unprecedented resolution.
SSRLSoft X-ray Spectroscopy at SSRL and LCLS
Synchrotron radiation experiments using soft x-rays are carried out at SSRL and the Advanced Light Source (ALS). For all experiments a photon energy range between 100- 1500 eV is necessary with a photon energy resolution of 0.1-0.5 eV that covers the C, N and O K edges of importance in the present proposal. At SSRL, there is currently a new soft x-ray beamline that came into operation in February 2008 denoted BL 13. With SPEAR3 this beamline performs extremely well in the important energy range and the new experimental end stations (see below) are permanently installed at one of the branch lines. This beam line will become the most intense source of soft x-rays with variable polarization in the U.S. Beam time is secured for 3 years through a collaborative access proposal agreement with SSRL.One of the experimental end stations contains two chambers, a preparation chamber together with LEED, TPD and reflection Fourier Transform Infrared Spectroscopy (FTIR) and a spectroscopy analysis chamber with XES, XAS and XPS capabilities. The instrument contains a Scienta electron spectrometer and a partial yield detector for XPS and XAS measurements, respectively. A new x-ray emission spectrometer optimized only for C1s, N1s and O1s provides an order of magnitude higher efficiency compared with previous spectrometers is in operation. The combination of techniques will allow for a detailed characterization of the species present on the surface for both UHV and ambient condition studies of adsorbates. This instrument is also movable to LCLS for ultrafast pump-probe studies.The second end station contains a newly constructed differential pumped ambient cell for XPS measurements, where pressures of the order of 10-50 torr should be obtained. It is based on a flow through gas cell, a new cryogenic differential pumping system and a Scienta SES 100 electron spectrometer.A third ambient pressure XPS end station is currently under construction that will complement the above instrument using hard x-rays. This is planned to reach 1 atmosphere using hard x- rays.There is a mobile UHV chamber with with LEED, TPD and reflection Fourier Transform Infrared Spectroscopy (FTIR) in a separate laboratory in blg 130 at SSRL. This system is currently being reconfigured to also include an additional small chamber for ambient pressure FTIR measurements.
EXAFS and Hard X-ray Spectroscopy at SSRL
SSRL has three high-flux wiggler beam line end stations, beam lines 6-2, 10-2, and 11-2, at which XAS and XSW measurements can be performed. Beam line 6-2 is fed by a 54-pole 1-tesla wiggler and accesses the energy range 2.05 – 17 keV. This station is highly versatile offering spectroscopy for a wide range of elements (S K-edge up to actinide L-edges), for microspectroscopy and imaging down to ~30 nm resolution, and high-resolution XES, HERFD XAS, resonant inelastic x-ray scattering (RIXS) and x-ray Raman scattering (XRS). Beam line 10- 2 is fed by a 30-pole 1.45-Tesla wiggler and is a general-purpose XAS facility and x-ray scattering facility that provides access to the energy range between about 4 and 38 keV. BL 11-2 is a high-performance wiggler end-station (26-pole 2-Tesla wiggler) dedicated to XAS. It is optimized for measurements between about 10 and 30 keV, but provides access to the range 5 to 38 KeV. All of these stations are equipped with harmonic rejection and focusing mirrors,which are necessary for measurements on challenging samples such as in situ studies of electrode-electrolyte interfaces. XSW and grazing-incidence XAS measurements are performed using a 7-axis spectrometer that can be used at any of these XAS end stations. The spectrometer allows samples to be positioned at any angle with respect to the polarization vector of the incident beam and provides ultralow backgrounds (no scattering from any spectrometer components, which is critical for dilute XSW measurements. Fluorescence-yield data are collected using a new 100-element Ge detector. Oriented single-crystals or electrodes having surface areas as small as ~1mm are easily positioned and measured using this device. In addition to these end-stations, SSRL has two high-flux wiggler side stations for XAS, which are fed by a 22-pole 2-Tesla insertion device. Beam line 4-1 is optimized for XAS measurements between ~5.5 and 30 keV, whereas BL 4-3 is optimized for experiments at 2.4 to 7 keV.
X-ray Scattering at SSRL
Beamline 7-2 at SSRL is used for most thin film and surface diffraction experiments and has a new 20-pole, 2 Tesla wiggler and has been upgraded with a new vertically focusing, cylindrical mirror and a sagittal focusing LN2-cooled monochromator. The energy range is 6-17 keV. There is a new dedicated eight-circle diffractometer. A Pilatus 100K hybrid-pixel area detector is used for improved throughput and time-resolution. A Pilatus 300K detector will be available in early 2013.
ReactorThe SUNCAT catalysis lab is located at SLAC and houses the custom designed high temperature and high pressure reactor from Altamira Instruments. High pressure carbon monoxide and hydrogen gases are delivered to the reactor by a Matheson Gas delivery system with excess flow safety switches and CO/H2 detection shut off alarms. The lab has open access to the fume-hood for nanoparticle synthesis and catalysts preparation.The Altamira reactor is computer-controlled and has furnace operating temperatures up to 650 ̊C. The pressure of the reactor is back-flow controlled from ambient up to 100 bar. Flow rates of up to 5 gases are mass-flow controlled (MFCs) and 1 liquid controlled by HPLC pump can also be introduced into the reactor. All of the reactor's functions are controlled by custom programmed LabView software.
The reactor is a dual function testing platform that has both a plug-flow reactor for catalyst testing and a quart U reactor for catalyst characterization. The catalyst testing module is able to conduct temperature programmed, isothermal, or pulse experiments with products continually analyzed by a SRI 3-column Gas Chromatograph (GC). The characterization unit can perform Temperature Programmed Desorption (TPD), Oxidation (TPO), Reduction (TPR), as well as Brunauer-Emmett-Teller (BET) surface area measurements using a dedicated Thermal Conductivity Detector (TCD). The reactor is designed with low (0 ̊C) and high (60 ̊C) temperature condensers. During standard operation, these condensers will also allow for periodic quality control mass-balancing experiments and also for the corroboration of results from the automated GC with the Mass Spectrometry (MS) and Nuclear Magnetic Resonance (NMR) facilities on the Stanford Campus.