Nanomaterials Characterization

Nanomaterials Characterization

The CNMS maintains an exhaustive assortment of capabilities to characterize organic, inorganic, and hybrid functional materials and structures.

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Inorganic and Hybrid Characterization

Optical Characterization and Laser Spectroscopy of Nanomaterials

  • Ultrafast femtosecond laser pump-probe spectroscopy of nanomaterials and composites
    A Coherent Legend Titanium sapphire based amplifier, providing pulses centered at 800 nm with ~2 mJ/pulse, 45 fs short durations, and operating at 1 kHz repetition rate, is used to pump an optical parametric amplifier (OPA), and a small portion is used to generate a spectrally broad white-light continuum (450-950 nm). With the tunable output of the OPA (400-2500nm) used as pump and the white-light continuum used as probe, this pump-probe setup is capable of studying solid- and liquid-phase samples in transmission and reflection modes. The spatial resolution in transmission mode is ~50 microns. An addition of a reflective microscope objective to reflection mode gives spatial resolution of ~10 microns. In both modes the temporal resolution is ~45 fs with sub-milli-OD absorbance sensitivity at 500Hz acquisition rate.
  • Ultrahigh resolution fixed/tunable Raman (micro/macro) spectroscopy (0.25 – 1.6 µm) with cryogenic stage and scanning capability
    Ultrahigh-resolution JY T-64000 monochromator permits Raman spectroscopy at several fixed excitation wavelengths > 10 cm-1 along with cryogenic (liquid He) temperature capabilities and X-Y scanning. A tunable ps laser-based OPO permits exciation at any wavelength (0.25 – 1.6 µm) with scattered wavelengths beyond 50 cm-1 of laser line). Also, tunable CW Ti:Sapphire laser for 780-950 nm excitation wavelengths. Inverted microscope with XY stage, and standard microscope with XY and piezo-Z stages.
  • Raman characterization of carbon nanotubes, oxides, polymers, 2D materials
    Conventional Renishaw confocal micro-Raman spectroscopy setup using 2 fixed wavelengths (785 nm, 633 nm) and 3-dim rotation/translation stages. X-Y mapping.
  • In situ Raman spectroscopy at <1500°C: CVD, annealing, electrochemistry
    Linkam hot stage annealing and growth chamber permits in situ dynamics of SWNT growth or processing under Raman microscope. Electrochemical cell under Raman microscope.
  • Microstat for low-temperature Raman, photoluminescence (PL), and second harmonic generation (SHG) measurements from 4K to 300K.
  • Combined microRaman, microPL, micro-absorbance, PL lifetime microscopy, second harmonic generation (SHG) and mapping for 2D materials
    Dual inverted/upright homebuilt Raman, PL, and absorption microscopy setup devoted to 2D materials; 405, 532 nm excitations available. Raman, PL and SHG mapping at low temperatures (4K - 300K). Lamp-based micro-absorbance. Time-correlated single photon counting PL lifetimes.
  • Tunable (0.25 – 1.6 µm) fs/ps laser system (nJ @ 76 MHz)
    Ti:Sapphire-based oscillator coupled to second- and third-harmonic generator crystals, along with OPO, may be run in either fs or ps mode. Coupled to confocal microscope with XYZ control for Raman spectroscopy or fluorescence measurements Provides nJ/ps-pulse at 76MHz to avoid damage to nanostructures.
  • Tunable (0.3 – 2.6 µm) high-energy, ultrashort, fs laser system (2.5 mJ @ 1 kz, 45 fs)
    Ti:Sapphire-based amplifier used to pump a high energy non-collinear OPA (accepts > 2mJ/pulse). A portion of the fundamental beam (800 nm) is used to generate a white-light supercontinuum for spectrally-resolved pump-probe techniques with ~10 micron special resolution in reflection mode. System also applicable to other nonlinear spectroscopies or fs laser processing (ablation, annealing, machining, polymerization, etc.).
  • Tunable (0.22 – 1.8 µm) ns laser system (mJ @ 10Hz)
    Tunable Nd:YAG –pumped OPO laser provides high pulse energies for in situ spectroscopic experiments (e.g. LIF) of nanomaterial growth environments, laser ablation synthesis, or nanomaterial luminescence.
  • UV-VIS-NIR Characterization of Nanomaterials by Absorption Spectroscopy
    Measurement and analysis of optical absorption spectra to investigate electronic energy levels and dispersion of solubilized nanomaterials in cuvettes, or materials on substrates. Cary 5000.
  • UV-VIS-NIR Fluorometry with remote fiber probing of liquids/surfaces
    Utilizes dispersed Xe lamp to excite fluorescence of solubilized or solid specimens. Two spectrometers (UV-VIS, and NIR) under computer control record fluorescence spectra. Excitation wavelength can be scanned to provide complete fluorescence maps vs. excitation wavelength. Fiber probe permits remote sampling of liquids or solid surfaces.

Electrical and Optoelectronic Characterization of Nanomaterials

  • Semiconductor parameter analyzer, cryogenic probe station, and both DC and AC characterization systems
  • AC impedance spectroscopy system based on the Zahner analyzer IM6 supports traditional electrochemical investigations like impedance measurements (10 µHz-8 MHz, 10 Ohm-1 GOhm), cyclic voltammetry, corrosion, current-potential curves, etc. with modeling software by THALES. AC-amplitude range 1 mV to 1 V. Impedance range 10 mOhm to 1 GOhm (+/-1 dB).
  • Special configuration Zahner controlled intensity modulated photospectroscopy capability enables dynamic photo-electric investigations including mixed photo electric transfer functions on photo-sensitive objects (e.g. photovoltaic materials).
  • Intensity modulated (LED based: UV-NIR) Photocurrent/Photovoltage measurement (solid, liquid samples).
  • Optical characterization (UV-NIR): absorbance, transmittance, reflectance (diffuse and specular), PL, Raman under electrical excitation. Cary 5000 with special attachments.Calibrated OLED efficiency measurement system (including angular light distribution).
  • Spectral photoresponse and calibrated PV efficiency measurement system

Physical Property Measurement System (PPMS) – DynaCool 9

  • Cryogen-free, 2.5 cm clear bore, with integrated high vacuum (10-4 Torr) 
  • Highly stable (±0.1% for T < 20 K, ±0.02% for T > 20 K) temperature from 1.8 to 400 K   
    • Continuous low temperature control and temperature sweep modes
  • Highly uniform (±0.01% over 3 cm) longitudinal field (± 9 T)
    • Linear, oscillating, and no overshoot modes

Options currently available:

  • Vibrating Sample Magnetometer (VSM)
    • rms sensitivity < 10-6 emu with 1 second averaging
  • Multifunction probe with calibrated thermometer and direct axial ports (for fiber optics, extra leads, etc.)
  • DC resistivity
    • 4 independent channels
    • Current drive from 2 nA to 8 mA
    • Resistances up to 5 GΩ
  • Electrical transport (for AC resistance, Hall effect, I-V, and differential resistance measurements)
    • 2 independent channels
    • 1 nV sensitivity, 10 nΩ resolution at 100 mA
    • AC and DC drive amplitudes from 10 nA to 100 mA
    • Resistances from 10 µΩ to 5 GΩ

Operando Spectroscopy: gas phase, electro- and photo-chemistry

  • Spectroelectrochemical Characterization of Nanomaterials and Composites
    Combined electrochemical measurements during spectrophotometry. Investigations of reduction-oxidation reactions; nA sensitivity using Faraday cage with three-electrode stand.
  • Environmental Test Chamber with Electrical and Optical Access
    A windowed vacuum chamber enclosed in an atmospherically-controlled enclosure with electrical feedthroughs and associated electronics to perform electrical measurements on samples and devices with controllable temperature, humidity, oxygen level. Labview-based Multimode Sensing (electrical, optical, weight) of thin films to programmable environmental exposure. Weight change using vacuum compatible quartz crystal microbalance. Optical windows permit optical excitation and observation of the samples.
  • Operando Raman spectroscopy
    Raman spectroscopy with multi-wavelength laser system (~20 laser excitations, from UV Raman to NIR Raman) and online mass spectrometry for in situ/operando study of catalysis.
  • In-situ FTIR pulsed catalytic reactor
    With dynamic FTIR analysis of samples under transmission or diffuse reflectance modes and with continuous analysis of reaction products by mass spectrometry. System permits rapid gas switching and pulsing.
  • Thermogravimetric analyzer with mass spectrometry (TGA-MS)
  • Volumetric gas adsorption
    BET analysis of surface area and pore size distribution using nitrogen. (Quantachrome Autosorb 1-C and Micromeritics Gemini).
  • Plug-flow gas phase catalytic reactor
    Measurements of catalytic activity and selectivity under variable temperature, steady state plug-flow reaction conditions with mass spectrometer and gas chromatographic analysis of reaction products. Reactions performed using an Altamira AMI-200 or 300 system. A SSITKA (Steady State Isotopic Transient Kinetic Analysis) capability is also available using the AMI-300 system.
  • Electrocatalyst (EC), Photocatalysis (PC), and Photoelectrocatalysis (PEC) Reactor Systems
    Reactor systems available for studying catalytic reactions, including PC and PEC (UV, visible and simulated sunlight illumination), with reaction products analyzed with gas chromatography and combinable with Raman spectroscopy for catalyst structure and surface species analysis.

X-ray and Neutron Scattering

X-ray Diffraction (XRD)

  • 2-circle X-ray diffraction
    X-ray powder diffraction with temperature-controlled sample environment. 77K to 1200K at 1 Bar, 273K to 1200K up to 10 Bar. Reactive gasses such as H2, CO for varying chemical composition in sample environment.
  • 4-circle X-ray diffraction
    4-circle plus translation stage, high temperature, in-plane thin film diffraction. Also texture, reflectivity, microdiffraction, reciprocal space mapping.
  • Small-angle X-ray scattering, SAXS
    Anton Paar SAXSess instrument for small-angle scattering to obtain nanoscale structural information. Also equipped for grazing-incidence measurements on nanomaterial films.

Neutron Scattering

  • CNMS users are encouraged to take advantage of the world-class neutron scattering facilities that are available at ORNL’s High-Flux Isotope Reactor (HFIR) and the Spallation Neutron Source (SNS). Beamlines of particular relevance to CNMS Scientific Themes include the small-angle scattering and diffractometry instruments on the HFIR cold source, HFIR thermal neutron diffraction and spectroscopy capabilities, and instruments at the SNS including the backscattering spectrometer and the liquids and magnetism reflectometers. Please visit the ORNL Neutron Sciences website for more information about these neutron scattering facilities.

    CNMS users who would like to incorporate neutron scattering as a supporting component in their user proposals may request neutron beamtime by checking the appropriate box on the CNMS proposal form and attaching the 2-page Neutron Scattering appendix to provide details of their beamtime request. However, if the primary thrust of the proposal is to obtain access to neutron scattering, prospective users must submit the proposal directly to the neutron scattering user program.

Macromolecular Characterization

The synthetic capabilities are complemented by extensive analytical resources for rigorous characterization of materials produced by CNMS staff and our user community. Additional capabilities applicable to polymeric materials (scanning probes, electron microscopy, Raman spectroscopy, etc.) are available in other groups within the CNMS or as shared resources at ORNL.

Molecular Weight Characterization

  • Size Exclusion Chromatography (SEC) 
    Multiple SEC systems are available for molecular weight characterization in a variety of media (organic, aqueous) and temperatures. All systems are equipped with multidetector systems that include light scattering for absolute molecular weight determination.
  • Temperature Gradient Interaction Chromatography (TGIC) 
    Unique chromatography technique for high resolution separation of polymers based on degree of polymerization rather than size. TGIC is particularly useful for the characterization of polymers with complex architectures.
  • Vapor Phase & Membrane Osmometry 
    For measurement of absolute molecular weights from 100 to 1,000,000 g/mol.

Solution Properties

  • Multi-angle Laser Light Scattering (18 angles) (MALLS) 
    Wyatt Heleos with Quasi-Elastic Light Scattering is capable of measuring molecular weight, hydrodynamic radii, and conformation of macromolecules in solution.
  • Simultaneous Static and Dynamic Light Scattering (DLS)
    ALV Goniometer system based on a rotary disk allowing for precise angular steps. Four detection angles separated by 34° in angular space and temperature can be controlled from -10 to 140°C for simultaneous measurements of static and dynamic light scattering. Instrument contains prisms for depolarized detecting to obtain rotational diffusion coefficient.
  • Absolute and differential refractive index detector
    Wyatt Technology Optilab Rex capable of measuring absolute refractive index and refractive index increment (dn/dc) of solutions at various temperatures and wavelengths.

Mechanical and Thermal Properties

  • Rheology 
    -TA Instruments Discovery Hybrid Rheometer (HR2) is capable of characterization of rheological properties of simple and complex fluids, gels, and elastomers over a wide temperature range of -160 - 600°C. Cone and plate, parallel plates (with solvent trap option), concentric cylindrical geometries, as well as the SER3 universal testing platform for extensional rheology are available.
    -Ubbelohde capillary viscometers of various sizes, capable of accurate measurement of low viscosity liquids from 0 - 150°C.
  • Dynamic Mechanical Analysis (DMA)
    TA Instruments 800 DMA with various operating modes and test probes available with temperature range from -160 – 600°C. Three point bending, fiber, film, and cantilever geometries are available.
  • Thermogravimetric Analysis (TGA)
    TA Instruments Q5000IR capable of measuring weight loss (0.1 mg sensitivity) at heating rates up to 1200°C under a variety of purge gases.
  • Differential Scanning Calorimeter (DSC)
    -TA Instruments Q2000 with temperature range from -180 to 550°C.
    -Nano DSC capable of characterization of the thermal stability and heat capacity of proteins and other macromolecules in dilute solutions. 

Spectroscopic Techniques

  • Matrix Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF-MS)
    Bruker MALDI-TOF Autoflex LRF instrument with imaging capabilities (5 micron spatial resolution) and capabilities for collisionally induced dissociation (CID) of any species. This system is equipped with the latest FlashDetector technology, enabling the instrument outstanding resolution (R > 26,000) and mass accuracy (≤  2 ppm) in reflection mode for addressing the complexity of co-polymer samples. With its real on-axis detector design (in linear mode), the system is capable of detecting extremely large molecules > 500 kDa.
  • Novocontrol broadband dielectric/impedance spectrometer
    Turnkey broadband dielectric spectrometer with temperature control and data acquisition system. Broad frequency range and high measurement accuracy based on high-resolution ALPHA-A analyzer. Frequency range: 3×10-5 – 4×107 Hz; Capacity: 10-15 – 1 F; Impedance: 0.01 – 1014 W; Loss factor accuracy < 3×10-5, resolution 10-5. QUATRO Cryosystem: -160°C to 400°C, with temperature stability 0.01°C. A few different sample cells are available, including plate electrodes of different sizes, liquid sample cells, and devices for ultrathin film measurements. The Alpha-A Modular Measurement System from Novocontrol for dielectric, conductivity and electrochemical impedance spectroscopy is developed especially for materials research. A wide range of topics can be addressed by the dielectric technique, including molecular dynamics in confining space, collective dynamics of liquid crystals, molecular dynamics in thin polymer films, and dielectric properties of semiconducting materials.
  • ​Rheo-dielectric capability
    TA Instruments HR2 hybrid rheometer coupled with Keysight E4980 Precision LCR Meter, capable of performing simultaneous rheological and dielectric measurements, in the temperature range -160°C to 350°C. The voltage range is between 0.005 to 20 V with a frequency range of 20 Hz to 2 MHz. Disposable plates are available for curing system.
  • Nuclear Magnetic Resonance Spectroscopy (NMR) 
    500 MHz multinuclear solution NMR Spectroscopy.
  • GC-MS 
    Hewlett-Packard 7890 GC with a 5975 mass spectrometer with EI and CI ionization capabilities.
  • UV-Visible-NIR 
    Varian Cary 5000 absorption spectrometer with liquid/solid sample holder, polarizers, diffuse reflectance, and specular reflectance accessory to probe the optical properties of solid, liquids, and solutions.
  • Fourier Transform Infrared Spectrometer (FTIR) 
    Bruker Vertex70 spectrometer with a variety of sample configurations including transmission, diffuse reflectance, variable angle ATR, and temperature controlled ATR. Instrument has capabilities for vibrational circular and IR reflectance absorbance spectroscopy.
  • Fourier Transform Infrared Spectrometer (FTIR)  Microscope
    Bruker LUMOS is a fully automated stand-alone FTIR microscope with an 8x objective and can be used in transmission, reflection and ATR mode. The measurement results in a single file including visible images, spectral data and sample information. For evaluation and visualization of the microscopic data the software provides powerful and intuitive Chemical Imaging functionality.
  • In Situ Fourier Transform Infrared Spectrometer (In-situ IR) 
    Bruker IRCube with various probes for in-situ monitoring of chemical reactions in progress. Temperature range from cryogenic to 250°C, spectral range 7500-750 cm-1.

Thin Film Characterization

  • Spectroscopic Ellipsometer 
    JA Woollam M-2000U for analysis of the thickness and refractive index of multi-layered structures. Temperature controlled and liquid sample environments available.
  • Contact Angle Goniometer 
  • The KRÜSS DSA 30 contact angle goniometer is equipped with a CCD camera and automated liquid handling controls allowing for precise measurements.
  • Optical Microscope 
    The Leica DM4500P is an intelligent function research polarized microscope with one-button access to bright field transmission or reflected (incident), dark field transmission, as well as polarized (transmission or reflected) microscopy and auto tracking of calibration for spatial quantitation. Samples are examined on slides as well as a thermal stage.