Chemical Research Support

 

Michael Elbaum, Head

The Department of Chemical Research Support, comprising 14 major units, offers a wide range of facilities for analytical and preparative chemical techniques to Institute scientists.

Each unit is headed by a Research Fellow or a Staff Scientist and is operated by qualified technical staff. The development program for the Department of Chemical Research Support and its mode of operation are supervised by Users Committees and scientific advisors.

Chemical and Biophysical NanoSciences (Person in charge: Shirley Daube)

The objectives of the unit are to promote research in processes and phenomena in (bio)chemistry, (bio)physics and materials research on the nano-meter scale, which cannot be addressed within the existing facilities of the WIS. An important aspect of this development is the technological need for miniaturization. Fundamental scientific issues are addressed in the areas of synthesis of nanomaterials, nanomanipulation of matter, chemistry and physics of mesoscopic objects and of biomaterials.

More specifically we refer to the emerging capability to design and prepare systems, showing predetermined heterogeneity at the atomic and molecular levels. Towards this, conceptual capabilities of molecular control and self-assembly (ready-made components) are combined with those of sturdy supra- or non-molecular components.

The center of the unit is a class 10,000 clean room complex, including facilities for optical and electron beam lithography, a mask aligner MA-6, a sputtering system for thin film deposition, and a dry etching ICP apparatus. The facility has, in addition, apparatus for thermal and electron beam evaporation of metallic and dielectric films, and equipment for surface characterization (wettability/contact angle; a Rudolf ellipsometer; a surface profiler-Dektak 6M). A chemical hood inside the clean rooms provides capabilities for a broad range of chemical manipulations. We also provide the means to fabricate micro-fluidic devices.

In order to advance research towards implementation of biologically active molecules as integral components in inorganic devices, the center includes a Nano Bio lab. The Nano Bio team aid physicists and chemists in the design and performance of their research involving biological molecules. In addition, the Nano Bio lab provides the means to perform experiments and produce pre-designed biological molecules using basic molecular biology and biochemical techniques. The lab is equipped with a variety of centrifuges, gel electrophoresis and imaging apparatus for nucleic acids and proteins, shakers/incubators for bacterial cultures, an autoclave and a sonicator, an AKTA basic FPLC protein purification apparatus, PCR machines, NanoDrop and NanoVuespectrophotometers, FLA-5100 FUJI fluorescent scanner, BioTek Synergy HT fluorescent plate reader, and a Hamilton liquid handling robotic system. A radioactive workstation for 32P and 35S labeling is also available.


Computational Chemistry Unit (Person in Charge: Mark Iron)

Computational Chemistry: The application of modern computational methodologies to calculate the chemical and physical properties of molecules and related systems.

State-of-the-art software packages can be used to accurately calculate molecular properties, including properties that can be measured experimentally. Through informed choice of methodology, the results of calculations can be used to predict molecular features, interpret experimental data and understand molecular effects and behaviour.

We use commercial software packages (such as Gaussian) and Molpro to calculate electronic structure, molecular properties and molecular mechanisms using ab initio, Density Functional Theory (DFT), semiempirical and force field methods. More specifically, the following information can be retrieved from electronic structure calculations:

Reaction Mechanisms

Electronic Properties

Spectroscopic Properties

Kinetics and Thermochemistry

Other services: Computational Chemistry Unit Website

Electron Microscopy Unit (Administrative Manager: Orna Yeger)

The Electron Microscopy Unit supports and facilitates research for all Weizmann Institute scientists, as well as other academic institutions and industrial clients. We provide service, collaboration and training on both short-term and long-term projects. Scientists can use equipment independently after appropriate training and supervision. Our goals include outreach to the microscopy community in Israel and abroad, as well as maintaining cutting-edge technology through continuing renewal and education.

Scanning Electron Microscopes (SEM)

All three SEMs at the EMU are high-resolution microscopes equipped with Field Emission Gun (FEG) sources.

Environmental SEM XL 30 (FEI): The instrument permits the observation of specimens in an environment of up to 10 Torr in pressure, which facilitates the study of wet samples. Besides its basic configuration, the ESEM 30 XL has a micromanipulator attachment, as well as an EDS detector from EDAX for X-ray elemental analysis.

The Ultra -55 from Zeiss, with declared resolution of 1.3 nm, has been outfitted with a BAL-TEC cryo-stage, permitting observation of frozen-hydrated specimens, and is also equipped with a STEM detector from Zeiss.

The Supra -55 (Zeiss) is outfitted with nanomanipulators, Electron Beam Induced Current (EBIC) imaging system, detectors for back-scattered electrons and cathodoluminescence, and an EDS detector from Oxford for X-ray elemental analysis.

Focused Ion Beam Microscope (FIB)

The Helios Nanolab 600 Dual Beam Microscope from FEI combines a focused ion beam (FIB) column with a SEM column. This microscope has excellent resolution for SEM imaging, along with nano-scale patterning by etching or material deposition. The FIB has a time-saving procedure for the preparation from block samples of thin cross-sections (lamellae) suitable for TEM analysis, using an advanced Omniprobe micromanipulator. In addition it can be operated in a three-dimensional "slice and view" mode for serial imaging of freshly cut sections. The instrument is equipped with a cryo-stage and EDS detector for X-ray elemental analysis. The Helios FIB/SEM is suitable for both materials and biological studies, as well as microelectronic device prototyping.

Transmission Electron Microscopes (TEM)

There are five TEMs at the EMU, each one meeting specific experimental needs. All microscopes are equipped with digital imaging cameras.

Materials Science

The CM-120 (Philips) is a 120kV instrument with a Super-Twin lens configuration, allowing for high resolution imaging of samples from Materials Science. It is equipped with an EDS detector for X-ray elemental analysis, and a Gatan US1000 CCD camera.

The Tecnai F-30 (FEI) with a FEG filament, is a high-resolution instrument (UltraTwin lens configuration, resolution 0.17 nm), equipped with a double tilt holder. Attached to this 300kV microscope there is a post-column Gatan Imaging Filter (GIF) which enables EELS measurements (electron energy loss spectra) and elemental mapping at nanometer scale. There is a US1000 camera installed above the GIF.

Biological Sciences

All three Biological TEMs are equipped with special blades for cryo-temperature applications and have digital slow-scan cameras (CCDs) for low-dose work.

The Tecnai Spirit T12 (FEI) (120 kV) has a BioTwin lens configuration, which provides the high contrast suitable for biological specimens, and allows for screening at extremely low magnifications with the objective aperture in place. The Megaview III side-entry camera provides TV-rate viewing and wide field-of-view. The bottom-mounted FEI Eagle 2k CCD provides high sensitivity and excellent optics.

The Tecnai T-12 (FEI) (120kV), with Twin lens configuration, balances between contrast and resolution, and uses a LaB6 filament for better brightness and coherence. The side-entry Gatan Erlangshen 500W camera provides wide field-of-view and TV-rate speed, while the TVIPS bottom-mount F224HD 2k CCD is extremely sensitive for super-lowdose cryoTEM applications. Tomography software is installed.

The Tecnai F20 (FEI), running at 200kV with a FEG filament, includes a Gatan Tridiem post-column energy filter for EF-TEM (energy filtered TEM) applications. There is also a host of analytical tools, including EELS, EDS for elemental analysis, a high-angle annular dark-field detector, DF/BF detector, and STEM capability. The microscope includes automated tomography capability for all configurations, including EF-TEM and STEM tomography.

Sample Preparation

Various pieces of auxiliary equipment for sample preparation are available in the unit. These include polishing apparatus, dimpling and ion milling machines, sputter, and physical evaporation apparatus, a critical point dryer, and several ultramicrotomes. The EM unit is equipped for conventional as well as low-temperature preparation of biological samples and immuno-labeling. There is equipment for cryo-applications such as high-pressure freezing (HPM 10, BAL-TEC), Freeze fracture device (BAF 60, BAL-TEC), cryo-plunging (including a new Leica automated plunger), AFS1 & AFS2 freeze-substitution devises (Leica) and cryo-microtome (Leica).

Image analysis

The facilities include software, servers, and workstations (linux and Windows) for advanced image analysis, for 3D reconstruction by tomographic and single-particle techniques, and for 3D visualization including stereo imaging.

Electron Microscopy Unit Website


Electron Spin Resonance (ESR) (Person in Charge: Lev Weiner)

The Electron Spin/Paramagnetic Resonance (ESR/EPR) Unit is equipped with a Bruker ELEXYS 500 (X and Q bands, 9.5 and 35 GHz) and ER 200 D SRC (9.5 GHz, X band) spectrometers. The various techniques for measuring the structure and properties of free radicals and paramagnetic ions in solid state and in solution are available for a wide range of temperatures.

The ESR Unit provides consultation and training for scientists interested in techniques for the detection and quantitation of oxidative stress in chemical and biological systems.

Site directed spin labeling of mutants of diamagnetic proteins provides unique information about properties of biopolymers under physiological conditions (pH, temperature, etc.)

A novel spin-tapping technique has been developed for quantitating and monitoring the kinetics of appearance of short lived reactive oxygen species and carbon-centered radicals in chemical, photochemical and biological systems. The technique can also be used to distinguish between the various reactive oxygen species, which include superoxide and hydroxyl (OH) radicals, as well as singlet oxygen (1O2). The ESR technique is applicable to strongly scattering and stained systems, such as organ homogenates and cell cultures.

A novel ESR approach has been developed for the quantitative determination of sulfhydryl groups (down to 10 -12 moles) in chemical and biological systems.


Laboratory for Magnetic and Electrical Properties of Materials (Person in Charge: Gregory Leitus)

The Unit provides research services for scientists developing new materials and devices with special physical properties. The Unit is equipped with a Magnetic Property Measurement System (MPMS XL - Quantum Design inc.), supplemented by additional devices (Keithley Instruments and SRS) providing DC (direct current), AC (alternative current), magnetic, and electric measurements. It allows:

In near future the Unit will be equipped by a dedicated Electrical Transport Measurement System (ETMS). The ETMS will provide precision testing of newly developed electronic materials and devices. The ETMS will consist of two parts:

Mass-Spectrometry and Chemical Analysis (Person in Charge: Arye Tishbee)

The Chemical Analysis Laboratory, provides training, consultation and method development for measurement, separation, purification, and isolation of a wide range of Organic compounds by Elemental analysis (CHN), Thermal Gravimetric Analysis (TGA), Gas Chromatography, Mass Spectrometry, Ultra-Performance Liquid Chromatography (UPLC), Amino Acids, Atomic Absorption spectrophotometry, RAMAN ,Micro RAMAN, Infra Red (IR), Micro IR spectroscopy, and Rapid Kinetics monitoring using Stopped Flow instrument, Gas Sorption analysis.

BET- Rapid Gas Sorption measurement 2m2 and up using Nitrogen.

Available equipment: NOVA 1000, Quantachrome Instruments.

The Thermal Gravimetry unit provided TGA analysis up to 1400C.

Available equipment: TA SDT Q600 Air or Nitrogen environment.

The RAMAN unit provides Raman measurements, using 1064 m 1.5W Laser excitation With a target area of 100 m.

Available equipment: Bruker FT RAMAN - RFS 100/S Ge Diode detector Spectral range of 3600 - 70 cm-1. (stokes shift) and 100-2000 (anti-Stokes shift) . Controlled by PC based OPUS spectral software.

The Micro RAMAN unit provides micro Raman measurements, using 780 nm and or 633nm laser excitation, magnification range from x5 to x100, for a variety of samples, including temperature controlled stage with operating range of - 200 to + 5000C.

Available equipment: Renishaw Micro Raman Imaging Microscope Controlled via a PC base software, with temperature control, moving xyz stage, dual lasers 633 and 780nm, and Grams 2c spectral manipulation software.

The IR unit provides standard IR measurements.

The Micro IR unit provides micro IR Transmission and reflection measurements.

Available equipment: TENSOR 27 FT-IR instrument attached to an IR/Optical Microscope. IRscope II, with Transmission and reflection, measurement modes. 15X IR Objective Measured Area: 20 m Minimum. Mid Range MCT detector 7000-600 cm-1.

Elemental Analysis for CHN.

Available equipment: Thermo EA 112 Elemental analyzer.

Rapid Kinetic Instrument unit provides Stopped Flow measurements, for enzyme reactions, Single, double, triple mixing with intermediate ageing, variable mixing ratio and dilution, volume operation using absorbance, fluorescence, or circular dichroism.

Available equipment: BioLogic MOS-450 with MPS 60. Consists of 4 syringes 10 - 2,5 ml, Min. Dead Time 0.98 ms, Min Ageing Time 1.63ms. Light source : 150W Xe, reflective achromatic monochromator , 180 to 800 nm. 1 nm. Steps. slits :2,4 or 8 nm, data acquisition rate, 50 ms/sample to 1000s/sample. Acquisition time 50 ms to 20s/nm.

The Mass Spectrometry Unit provides mass spectra for the determination of molecular weights and structure elucidation of organic compounds up to 4000AMU including labile metal complexes, and for Peptides and proteins up approx. 18,000AMU Detection limit approx. 50 pg. GC-MS Analyses of complex mixtures of volatile organic compounds up to 700 AMU with system peak matching and library search. Detection Limit approx. 10pg. Accurate mass FD analysis of semi volatile and non soluble organic compound.

Available equipment: ESI-MS Micromass ZQ 4000 Mass Spectrometer equipped with ESI and ESCI probes for Electrospray and ESCI analysis. Connected to a MassLynx data station. UPLC - MS Micromass Q-TOF Premier, Quadrupole Time Of Flight High Resolution Mass Spectrometer equipped with ESI for Electrospray analysis. Connected to a Masslynx data station. Field Desorption FD-MS Micromass GCT Premier TOF equipped with FD probe .GCQ Polaris Gas Chromatograph Mass Spectrometer for volatile compound, connected to Xcalibur data station equipped with NIST Library search capabilities.

The Amino Acid Analyzer Unit provides qualitative and quantitative Analysis of protein and peptide hydrolyzates. Detection Rage of 100-3000 pmoles, using OPA and FMOC pre column derivatization, monitoring at UV, using reverse phase separation. Detection range of 5 - 3000 pmole using AccQ.Tag pre column derivatization, and monitoring Fluorescent emission.

Available equipment: Waters PicoTag Work Station for gas phase Hydrolysis Waters 2695 Alliance HPLC equipped with fluorescence and Diode Array detectors and autoinjector , utilizing AccQ.Tag chemistries for the analysis of Hydrolizates and some physiological Amino acids.

The Atomic Absorption unit provides Analysis for a verity of elements in sensitivity of few mg/L depending on the analyte, a wide range of lamps is available for different elements. Both Flame and Graphite Oven atomizers are available.

Available equipment: Perkin Elmer Analyst 400 atomic absorption unit.


Molecular Modeling Unit (Person in Charge: Miriam Eisenstein)

This unit offers diverse structure-analysis and molecular-modeling services to many groups in the Chemistry and Biology faculties. These include homology modeling of proteins, protein-protein recognition and docking, and conformational analyses. The available equipment is a 4-core PC and 2-core PC equipped with a high-end graphics card. Several different computer programs and packages are in constant use: For example, the Accelrys InsightII package for display, homology modeling, energy minimization and molecular dynamics and the Gromacs package for extensive molecular dynamics simulations. The protein-protein docking program MolFit, originally developed by E. Katchalski-Katzir, I. Shariv, M. Eisenstein et al, is continuously being improved and extend by Dr. Eisenstein.

MolFit Website


Nuclear Magnetic Resonance (NMR) (People in Charge: small molecules - Leonid Konstantinovski, peptides & proteins - Tali Scherf, magnetic resonance imaging - Peter Bendel and Inbal Biton)

The Nuclear Magnetic Resonance (NMR) Unit comprises two facilities: one for High Resolution NMR Spectroscopy, and one for Magnetic Resonance Imaging. Spectroscopy encompasses two labs, with focus on small organic molecules and on biological macromolecules.

mainly for small molecules:

The low-field NMR instrument AVANCE III-300 is used primarily for routine identification and standard work. It is equipped with a 5mm (QNP) probe with z-gradient for 1H, 13C, 19F and 31P measurements and Broad Band BBO (5mm) probe.

The new AVANCE III-400 spectrometer includes five different probes: a unique 5 mm (PBBO) Broad Band probe with z-gradient and automatic tuning and matching (ATM), a 5mm (BBI) Inverse with z-gradient, a 5mm (TXI) Inverse (triple-channel) with z-gradient, a 10mm (BB) multinuclear probe covering the range 107Ag to 31P, and a 10mm (BB) low-frequency probe (39K 193Ir).

The AVANCE I-500 provides three channels and is equipped with six unique probes: a micro 2.5mm Triple-Resonance Inverse (TXI) probe(1H, 13C, 15N) equipped with z-gradient, a 5mm multinuclear Broad Band (BBO) probe in the frequency range 109Ag to 31P equipped with ATM as well as z-gradient, a 5mm Inverse Triple-Resonance (TBI) probehead in multinuclear version, a 5mm (1H, 31P, BBlow) with z-gradient, a 5mm Broad Band (109Ag - 31P) Inverse probe (BBI) that includes z-gradient, ATM, as well as a special tuning for 103Rh, a standard 5mm (QNP) probe for 1H, 13C, 19F, and 31P measurements, and a CP-MAS probe.

Mainly for macromolecules:

The Bruker DMX-500 is mainly used for specialized research, including 2D NMR and biologically oriented work. The instrument is equipped with dedicated NMR probes for 1H, 2H, 13C, 15N, and 31P measurements, as well as for "inverse" experiments, and a 13C CP-MAS probe. It has a new, 5mm Triple-Resonance Inverse CryoProbe, TXI, (1H, 13C, 15N) equipped with Z-gradients.

The 800 MHz high-resolution spectrometer (Bruker, DRX Avance-800) provides access to the highest magnetic field currently available in Israel, enabling state-of-the-art high-resolution multi-dimensional experiments for macromolecular structure determination. The accessories include a multi-nuclear TXI probe with z gradient (1H, 13C, 15N, 5mm), a multi-nuclear QXI probe with x, y and z gradients (1H, 13C, 31P, 5mm), and two solid-state MAS probes covering both low and high multi-nuclear frequency ranges. Recently, a new, 5mm Triple-Resonance Inverse CryoProbe, TCI, (1H, 13C, 15N) equipped with Z-gradients was installed, which uses an automatic tuning and matching (ATM) device.

Mainly for imaging:

A Bruker Avance III-400 widebore spectrometer is used for NMR microscopic imaging. Spectroscopic capabilities include 1H and broad band multi nuclei probes and an automatic QNP probe, switchable by computer. Imaging is provided by two systems: a microscopy probe includes actively shielded gradients (up to 200 G/cm) with 5 mm rf coils for 1H, 1H/ 13C and 1H/ 31P. A mini-imaging probe with actively shielded gradients (up to 150 G/cm) includes several 1H RF coils, with diameters between 4 and 30 mm. The spectrometer is used mainly for research in biology and for non-invasive physiological and metabolic measurements of small samples.

For imaging of large specimens including whole plants and small animals there are two horizontal, wide-bore Biospec systems from Bruker. The first spectrometer is an Advance DBX version, based on a 4.7 Tesla magnet with a 30 cm bore. The system has fully broadband dual-channel operation, self-shielded gradients and an assortment of resonators and surface coils with active coil detuning for crossed-coil operation. This instrument is most flexible in the types of samples it can accommodate, and projects have ranged from studies of spinal cord damage to rock fracture models. The second system, a Bruker Avance-II 94/20, is dedicated to animal imaging. It has a 9.4 Tesla magnet and an accessible bore of 20 cm. It is located in the new Center for Preclinical Research building (Mamtak), and is operated in collaboration with the Department of Veterinary Resources.

High-Resolution NMR Website

MRI- Tips and Bugs


Organic Synthesis Unit (Person in Charge: Veronica Frydman)

The Organic Synthesis Unit provides a service to all the scientists in the Institute who need non-commercial chemicals in order to perform their research work. The Unit carries out upon request the synthesis and characterization of a wide variety of organic compounds, including (but not limited to) polymers, porphyrins, steroids, isotopically-labeled oligopeptides, spin-labeled chemicals, etc. Synthezised quantities range from small to medium scale. The Unit counts with a fully equipped organic synthesis laboratory, and uses the facilities provided by other units (e.g., NMR, ESR, MS, etc.) to characterize the intermediates and final products. The staff also provides consultation about experimental procedures and techniques.


Solar Optics Design; Mathematical Modeling (Person in Charge: Akiba Segal)

This unit offers assistance in the modeling of the solar optics systems connected with the main research around the utilization of concentrated solar energy at high temperatures. In this range we have a remarkable experience in the development of the non-imaging secondary optics devices. As example, we designed a new optical feature, which was added as a 75 m2 reflector attached to the Solar Tower at 49 m above ground level. Using this reflector, about one megawatt of concentrated sunlight can be beamed down onto a ground target. This is a unique feature exists only at the Weizmann Institute. We also designed the biggest solar energy concentrator in the World, which was also built, according to our design, at the Weizmann Institute. Both the tower reflector and the big concentrator are currently used in various researches that are recognized as between the most advanced solar researches in the World. We have also capabilities to design small energy concentrators, providing big light energy concentration, which can be used for various chemical processes, studied in the Faculty laboratories, which need high temperatures. These concentrators will use the solar energy with an appropriate optical system from the Institute's solar facilities, or, in laboratory, using an adequate light source as simulator of energy. Also we can offer assistance in conceiving mathematical models for various chemical processes that are in study by the scientists from the Faculty in order to complete and finish their research work. This means that we can provide consultation and development of methods for solving the various mathematical models and, eventually, the mathematical optimization of the results.


Spectroscopy Unit (Person in Charge: Leonid Konstantinovski)

Infrared (IR) Spectroscopy consists of a Nicolet 460 single beam infrared Fourier transform spectrophotometer (FTIR) fully operated by a Nicolet computer (512K RAM, 13" high-resolution color monitor) equipped with two internal 3.5 inch disk drives for programming and data storage. The optical bench provides a maximal resolution of 2 cm-1 over the complete spectral range from 4000 to 400 cm-1 and contains a sample compartment built especially for introducing various IR accessories, such as gas cell, ATR, and so forth. This equipment is suitable for a large variety of analytical IR applications, offering high sensitivity and photometric accuracy and computerized data manipulation capabilities.

In addition, the Spectrometry Unit provides facilities for measuring optical absorption, optical rotatory dispersion (ORD) and circular dichroism (CD) at a wavelength range of 180-1000 nm and at a temperature range of -190C to 70C.

Available equipment : Aviv Model 202 spectropolarimeter, UV-visible diode array spectrophotometer, Beckman DU-7500.

The Unit for Radioactive Counting provides facilities for scintillation counting of b-radioactive sources. The unit is equipped with a Beckman Model LS7500 b-scintillation counter.


Surface Analysis Unit (Person in Charge: Sidney Cohen)

The surface analysis group provides the means for a variety of surface-sensitive measurements. These include chemical composition of the exposed atomic layers, atomic scale surface topography, electronic and mechanical surface properties, and detection of adsorbed molecules. The various units of this group are housed in two laboratories and include facilities for rudimentary sample preparation and cleaning, such as ozone cleaner, snowjet cleaning, and solvent cleaning station with clean hood.

The Scanned Probe Microscopy Unit contains three separate scanning tunneling/scanning force microscopes (also known as atomic force microscopes AFM):

These microscopes enable determination of surface topography and mechanical and electrical properties at resolutions ranging from tens of microns down to atomic scale.

In addition, the laboratory houses an Agilent instrumented Nanoindenter equipped with XP and DCM heads for force ranges up to 500 mN or 14 mN respectively, and Nanovision for nm-scale mapping of the surface in-situ with the indenter tip.

The Electron Spectroscopy Unit is a multifaceted ultra high vacuum (below10-9 torr) system for surface analyses. The main analysis chamber includes a Kratos Axis-Ultra x-ray photoelectron spectrometer (XPS), which detects elements and determines their chemical state on the surface at depths up to 15 nm and sensitivity of 0.1%. A monochromatic x-ray source and improved mapping capabilities are offered by this instrument, down to 3 m spatial resolution in parallel imaging mode. The system includes an ultraviolet lamp for valence band measurements, ion gun for sputtering the surface and for ion scattering spectroscopy (ISS), and a flood gun for insulating samples. In addition, Auger electron spectroscopy at lateral resolution of 100 nm can be performed in the same chamber. A second spectrometer for XPS (Kratos AXIS-HS) is available in the laboratory, supported by a VG Low Energy Electron Diffractometer (LEED) for determining the surface crystalline structure.

Based on the XPS technique, we are capable of studying electrical properties of surfaces as well, using chemically resolved electrical measurements (CREM). These measurements are performed in-situ and do not require a physical electrode contact. They can provide I-V curves at selected surface positions resolved laterally and/or vertically, photovoltaic characteristics, sample work function and other electrical features all acquired in parallel with the chemical analysis.

Surface Analysis Unit Website


X-Ray Crystallography (Person in Charge: Linda J. W. Shimon)

The X-ray Crystallography Laboratory of the Weizmann Institute is both a service and user facility. It is well equipped for the single crystal diffraction experiments needed for structural biology and chemistry research. We apply a variety of experimental methods to these investigations. Since each crystal is unique, we tailor each experiment to the individual sample and offer expertise in the following areas:

A structure determination of molecular crystals will typically involve the following:
The measurements of organic and organometallic materials are performed using a Bruker KappaApexII CCD diffractometer with MiraCol optics or a Nonius KappaCCD diffractometer mounted on a FR590 generator, both utilizing Mo radiation. A Nonius Mach3 Kappa full 4-circle diffractometer mounted on a FR590 generator is also available with Cu radiation. Data collection may be performed at either LN or ambient temperatures. Low temperature has many benefits for X-ray structure determination, including better quality data in less time than room-temperature work and the ability to handle highly reactive compounds with minimal fuss. We typically collect data at 100K, but on occasion, destructive phase transitions force data collection at higher temperatures

For the Structural Biologists, the X-ray laboratory is a user facility. Macromolecular crystallographic measurements are made on two R-Axis IV++ systems. The image plate detectors are mounted on RU-H3R Rigaku rotating anode generators equipped with Osmic confocal focusing mirrors. One of these systems is outfitted with a 2-theta stage allowing high resolution data collection. Both systems are equipped with Oxford cryostream cooling systems for LN, low-temperature measurements. Also available in the laboratory are light-microscopes for sample inspection and mounting as well as digital cameras for crystal photography. Training is available for users, so that they can perform their own experiments.

X-ray Crystallography Unit Website


X-Ray Diffraction Lab (Person in Charge: Yishay Feldman)

The aim of the X-ray diffraction laboratory is the structural characterization of natural and synthetic solids including powders, thin films, single- and poly-crystals. X-ray diffractometry is a powerful, non-destructive technique capable of determining a number of parameters which characterize the structure of the irradiated material. The volume of a sample which can be studied at a given time depends on the dimensions of the X-ray beam (up to 15 x 15 mm) and on the penetration depth of the X-rays used. In the case of our generators (Cu target, ?av=0.154nm) the penetration depth reaches several tens of micrometers in inorganic materials and millimeters in organic materials. High intensity X-ray sources and high quality X-ray optics allow us to obtain a sufficiently strong diffraction signal even when the X-ray beam dimension is less than 200 m.

Our lab is equipped with three X-ray generators manufactured by Rigaku Ltd. (Japan). The instrumentation includes a wide angle X-ray scattering (WAXS) camera affixed to a RU200 rotating anode generator (12kW) with an imaging plate for data acquisition and two theta-theta vertical diffractometers: a sealed tube generator-based ULTIMA III (2kW) and a rotating anode generator-based TTRAXS III (18 kW). Data acquisition for the latter two is computer controlled and data analysis is performed on separate platforms with Jade9.1 software. Search/match protocols use the Powder DIffraction File (PDF-4+) of the ICDD (International Center for Diffraction Data) on CD-Rom.

The two theta-theta diffractometers have a combination of modern XRD software and hardware which together permit almost all the structural characterization of solids that can be realized under laboratory conditions. These include:

It should be noted that the TTRAX III is the only diffractometer of its kind manufactured today i.e. a rotating-anode theta-theta diffractometer- which makes possible the characterization of a horizontally mounted sample with 18 kW of X-radiation. Our instrument is the only one of its kind in Israel and there are only a few in Europe and in the US. Its high intensity X-ray beam and high quality X-ray optics allow us to obtain good powder diffraction patterns from gold films with thickness as small as 2 nm. Another example of the extraordinary capabilities of this instrument is the high quality XRD patterns obtained in transmission geometry from inorganic membranes with thickness of half a micron and lateral size of 200 microns.

Recently a polycapillary optic has been acquired which, when installed on the RU200 generator, will allow us to produce an X-ray microbeam (about 20 m) with very high intensity (the manufacturers compare the flux density in the focal spot to that of a regular synchrotron beam) for WAXS measurements. Possible applications include characterizing the two-diimensional heterogeneity of both biological and inorganic samples as well as determining crystallite size in the range up to 1 micron. Another planned addition is a high speed, high sensitivity, high resolution solid state X-ray detector which will be used in conjunction with the existing variable temperature attachment in order to avoid long data acquisition times at low and high temperatures which may cause sample damage. It also will improve the angular resolution of measured XRD profiles up to 0.02 in 2-theta and will markedly reduce the turn-around time for heavy use of the Ultima (or TTRAX) diffractometer.


Light Scattering (Person in Charge: Ellen J. Wachtel)

Dynamic light scattering (DLS), also called quasi-elastic light scattering (QELS) or photon correlation spectroscopy (PCS), is a widely used, rapid and nondestructive technique to determine the hydrodynamic size and aggregational state of particles dispersed in solution. The particles may be biological macromolecules such as proteins or oligonucleotides, surfactant aggregates (micelles or vesicles), or inorganic nanoparticles. Both organic and aqueous solvents may be used. Information on translational diffusion of the particles is obtained from intensity fluctuations measured on the microsecond to millisecond time scale. The diffusion constant may be related to a hydrodynamic radius via the Stokes - Einstein relationship. When the dispersion contains a mixture of sizes, mathematical algorithms are used to extract a weighted distribution.

The department DLS instrument (Viscotek, model 802 DLS) is characterized by high sensitivity, fast and accurate temperature control ( 0-90oC), and low sample volume. It uses a 50mW fiber coupled laser diode light source, with wavelength 830nm, in order to avoid strong absorptions in the visible. The suitable size range of particles is 0.5nm - 0.1 micron in hydrodynamic radius.

http://www.weizmann.ac.il/Chemical_Services/ 

Staff

Professor

Michael Elbaum1, Ph.D., University of Washington, Seattle, United States

Senior Research Fellows

Hagai Cohen, Ph.D., Technion-Israel Institute of Technology, Haifa, Israel
Sidney Cohen, Ph.D., Weizmann Institute of Science, Rehovot, Israel
Miriam Eisenstein, Ph.D., Weizmann Institute of Science, Rehovot, Israel
Arye Tishbee, Ph.D., University of Houston, Houston, United States

Senior Staff Scientists

Peter Bendel, Ph.D., State University of New York, Stony Brook, United States
Yishay (Isai) Feldman, Ph.D., Weizmann Institute of Science, Rehovot, Israel
Konstantin Gartsman, Ph.D., Physical Technical Institute, Russian Federation
Eugenia Klein, Ph.D., Weizmann Institute of Science, Rehovot, Israel
Leonid Konstantinovski, Ph.D., Rostov University, Rostov on Don, Russian Federation
Ronit Popovitz-Biro, Ph.D., Weizmann Institute of Science, Rehovot, Israel
Akiba Segal, Ph.D., Jassy University, Romania
Linda J.W. Shimon, Ph.D., Weizmann Institute of Science, Rehovot, Israel
Vera Shinder, Ph.D., Moscow University, Biochemical Institute, Academy of Science
Lev Weiner, Ph.D., Institute of Catalysis, Novosibirsk, Russian Federation
Sharon G. Wolf, Ph.D., Weizmann Institute of Science, Rehovot, Israel

Associate Staff Scientists

Shirley Daube, Ph.D., University of Oregon, Eugene, United States
Veronica Frydman, Ph.D., University of Buenos Aires, Buenos Aires, Argentina
Gregory Leitus, Ph.D., Metallurgy Institute, Russian Academy of Sciences, Moscow, Russian Federation
Tali Scherf, Ph.D., Weizmann Institute of Science, Rehovot, Israel
Eyal Shimoni, Ph.D., ETH, Zurich, Switzerland

Assistant Staff Scientists

Yoav Barak, Ph.D., Weizmann Institute of Science, Rehovot, Israel
Tatyana Bendikov, Ph.D., Technion - Israel Institute of Technology, Haifa, Israel
Arkady Bitler, Ph.D., Leningrad State University, Leningrad, Russian Federation
Yael Diskin Posner, Ph.D., Tel Aviv University, Tel-Aviv, Israel
Mark Alan Iron, Ph.D., Weizmann Institute of Science, Rehovot, Israel
Elena Kartvelishvily, Ph.D., Technion - Israel Institute of Technology, Haifa, Israel
Palle Von Huth, Ph.D., Weizmann Institute of Science, Rehovot, Israel

Engineers

Gregor Rory Leitch
Alexander Yoffe, M.Sc., University of Tashkent, Russian Federation

Consultant

Itai Carmeli (left September 2010)

Visiting Scientist

Rotem Asaf, Harvard University , MA, U.S.A.

Postdoctoral Fellow

Estelle Kalfon-Cohen, Hebrew University of Jerusalem, Israel

Administrator

Hila Shochat

1Department of Materials and Interfaces