FUNCTIONAL HYBRID NANOSTRUCTURES CAPABILITIES

Laser Vaporization Synthesis of single-walled nanotubes, nanowires, and nanoparticles - including in situ diagnostics

• ns-Laser Vaporization Synthesis of SWNTs, NWs, NPs
  SWNTs and nanowires are produced by pulsed Nd:YAG laser-irradiation (30 Hz, Q-switched or free-running) of composite pellets in a 2" tube furnace with variable pressure control. Excimer laser ablation of materials into variable pressure background gases is used for nanoparticle generation in proximity of ns-laser diagnostics.
• High-power ms-laser vaporization bulk production of nanomaterials
  SWNTs (primarily), SWNH (single-wall carbon nanohorns), nanoparticles and nanowires are produced by robotically-scanned 600W Nd:YAG laser-irradiation (1064 nm) of targets at controlled pressure in various atmospheres (including CVD gases) at <1200°C inside a 3" tube furnace. Rapid sampling capability.
• ns-Laser Vaporization Synthesis of nanoparticles
  Excimer laser ablation of materials into variable pressure background gases is used for nanoparticle generation in proximity of ns-laser diagnostics (located outside of the CNMS).
• Gated ICCD imaging and spectroscopy of laser vaporization processes
  Intensified CCD-array photography (5-ns resolution) and intensified, gated diode-array spectroscopy of laser vaporization plumes and nanomaterial synthesis processes. Utilizes 2" windowed tube furnace for nanotubes and nanowires (variable pressure, controlled flow) or PLD chamber. Secondary laser illumination for LIF, LII, LIP and broadband OAS possible.

CVD: Thermal, molecular beam, PECVD (microwave) of CNTs, nanowires, arrays - including in situ diagnostics

• Thermal CVD of SWNT, MWNT, and vertically aligned nanotube arrays (VANTAs) on substrates
  Several systems are available for nanotube growth:
  • CVD system in a 3"-i.d. tube furnace (1200°C) with pressures down to ~ 1 torr and fast-acting electro-pneumatic valves for switching source gases; integrated time-resolved reflectivity diagnostics and remote video imaging of growth dynamics. The system is in proximity of tunable ns-lasers for laser diagnostics of CVD processes, or for combined laser-CVD (e.g. for doping of nanotubes during CVD growth, or laser-generation of catalyst nanoparticles for CVD, etc.).
  • Thermal CVD of single and multiwall carbon nanotubes, nanotube arrays, and nanotube patterns at atmospheric pressure and flow.
  • Ferrocene-enhanced thermal CVD (atmospheric pressure) growth of up to 1-cm long multiwall nanotube arrays and patterns. The system allows real-time study of vertically aligned growth.
• Molecular Beam Growth of CNTs on substrates
  Molecular beam delivery of feedstock to substrates at low pressures for growth of random and vertically aligned single, double and multiwall carbon nanotubes and nanotube patterns on various substrates. Equipped with time-resolved reflectivity for real-time study of vertically aligned growth.
• Time-resolved reflectivity (TRR) of aligned nanomaterial growth rates by CVD
  Utilizes stabilized HeNe laser beam reflectivity Fabry-Perot interference oscillations and attenuation to directly measure the height of vertically-aligned nanostructure arrays during growth – for growth rate, catalyst assessment.
• Rapid thermal laser-CVD growth and processing facility with X-Y-Z control
  Utilizes 600W Nd:YAG laser (either broad beam or focused to ~ 600 microns) to laser-heat substrates rapidly for nanomaterial synthesis or annealing under controlled pressure and flow, including CVD gases.

Oxide Heterostructure Pulsed-Laser Deposition with high-pressure RHEED

• Complex oxide heterostructure PLD
  Complex oxide film and superlattice growth by pulsed-laser deposition (including magnetic, ferroelectric, superconducting materials; strain-engineered heterostructures) with in-situ high-pressure RHEED for atomic-layer control
• Oxide Target Synthesis
  Standard facilities for milling, drying, pressing, and sintering of oxide materials, to prepare PLD targets.

Laser/nanomaterial processing

• Photolithographic-, E-beam-, FIB-Patterning/Wiring of Nanomaterials for Devices
  (Through the Nanofabrication Research Laboratory) Processing of nanomaterials including spin-coating, dielectrophoretic deposition, etc. combined with photo- and e-beam lithographic techniques and FIB electrode placement for the addressing of nanomaterials as prototype devices.
• Laser/nanomaterial interactions and X-Y-Z processing
  High-power (500W) Nd:YAG (1064 nm) or low-power (30 mW) fs/ps addressable light for laser-direct write, machining, and annealing of nanostructures and composites under controlled atmospheres.

SWNT Purification, Functionalization, and Composites

• Chemical purification and functionalization of carbon nanotubes
  (With the Macromolecular group) Synthetic chemistry labs and associated equipment specializing in the processing of laser-vaporization produced SWNTs to very high purities and chemical functionalization treatments tailored for specific applications. Quantitative purity assessment of nanotubes.
• Thermal diffusivity measurements of macroscale nanocomposites
  Fast infrared transit time measurements and analysis for thermal diffusivity determination.
• Electrospinning of nanocomposite fibers
  Co-solubilization of nanomaterials and fiber matrix in solvent, especially SWNTs in polymers, to form prototype nanocomposite fibers (located outside of the CNMS).

Electrical Characterization of nanomaterials

• Semiconductor parameter analyzer, cryogenic probe station, and both DC and AC characterization systems are now being installed.
• 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).

Optoelectronic Characterization of nanomaterials

Laser-based Spectroscopy of nanomaterials

• UV-VIS-NIR Characterization of SWNTs, etc. by Absorption Spectroscopy
  Measurement and analysis of optical absorption spectra to investigate electronic energy levels and dispersion of solubilized nanomaterials.
• 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.
• Ultrafast laser spectroscopy of nanomaterials and composites
  Utilizing tunable fs/ps laser, and fs-amplified systems (see below) with white-light continuum pump-probe spectroscopy. Set up includes a 250 mm optical delay line (sub micron resolution and repeatability), a ¼ meter spectrograph and CCD array.
• Raman characterization of carbon nanotubes, oxides, polymers
  Confocal micro-Raman spectroscopy and assessment of SWNT diameters, defect densities, dispersion and alignment in composites, etc. using 2 fixed wavelengths (785 nm, 633 nm) and 3-dim rotation/translation stages.
• Tunable Raman (micro/macro) spectroscopy (0.25 – 1.6 µm)
  New system utilizing tunable ps laser coupled with high-resolution JY T-64000 monochromator to permit Raman spectroscopy at any wavelength (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.
• In situ Raman spectroscopy at <1500°C: CVD, annealing, electrochemistry
  Linkam stage annealing and growth chamber permits in situ dynamics of SWNT growth or processing under Raman microscope. Electrochemical cell under Raman microscope.
• Tunable (0.25 – 1.6 µm) fs/ps laser system (nJ @ 80 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 80MHz to avoid damage to nanostructures.
• Tunable (0.3 – 2.6 µm) High energy, Ultrashort, fs laser system (2.5 mJ @ 1 kz, 40 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. 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.

Spectroelectrochemistry

• 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.

Capabilities provided by other CNMS groups
Macromolecular Nanomaterials
Catalytic Nanosystems
Scanning Probes & Nanoscale Physics
Electron Microscopy, Neutron and X-ray Scattering
Nanomaterials Theory Institute
Bio-Inspired Nanomaterials
Nanofabrication Research Laboratory
General Characterization Facilities
Collaborating Facilities