DeMar Photonics - Newsletter

Featured publications abot research with NSOM Godwit

Two-Photon Absorption Near Field Imaging of Non-Fluorescent Organic Nanoparticles
Jeffery E. Raymond, Theodore Goodson III*
Departments of Chemistry and Macromolecular Science & Engineering, 930 N.
University Ave., University of Michigan, Ann Arbor MI 48109

We present here the first reported use of fiber aperture near-field optical microscopy (NSOM) for the purpose of characterizing directly the two-photon absorption (TPA) of non-emissive nanoparticles. It will be displayed how this empirically driven technique can provide per particle and per molecule assessment of the two-photon cross-section (TPACS) by extracting the non-linear optical (NLO) signal from that due to scattering and far-field effects. This is shown with the investigation of a known two-photon responsive porphyrin dimer, which has exhibited both severe fluorescence quenching and a multiple order of magnitude TPACS enhancement in aggregate, after self-assembly into uniform nanoparticles. A particular emphasis will be placed on the viability of this technique for the characterization of low-scatter optical limiting organic nanomaterials.

NSOM, two-photon, porphyrin dimer, organic nanoparticle

Single-Particle Two-Photon Absorption Imaging and Enhancement Determination for Organic Nanoparticles
Jeffery E. Raymond and Theodore Goodson, III*
Departments of Chemistry and Macromolecular Science & Engineering, University of Michigan, 930 North University Avenue,
Ann Arbor, Michigan 48109, United States

The lack of characterization regimes available for the rapid single particle assessment of two-photon (TPA) response in nanomaterials remains a critical barrier to nonlinear optical device development. This is particularly true of nonemissive species whose TPA must often be characterized in the bulk. In this study, self-assembly is used to produce uniform nanoparticles from a novel porphyrin dimer, which is known to exhibit both severe fluorescence quenching
and two-photon cross section (TPACS) enhancement when assembled into macromolecules.
We present here the first reported use of fiber aperture near-field optical microscopy (NSOM) for the purpose of characterizing directly the TPA of
nonemissive nanoparticles, observing directly a 5-fold enhancement in TPA response. This assembly/characterization regime provides a fast and fully actualized method for the generation of low-scatter optical-limiting organic nanomaterials where domain size, morphology control, and TPA enhancement are all critical to application viability and unobservable via bulk measurements.

Quantitative Non-Linear Optical Imaging in the Nano- Regime
Jeffery Raymond, Theodore Goodson III
Department of Chemistry, Department of Macromolecular Science and Engineering
University of Michigan, Ann Arbor Michigan

The development of functional solid state non-linear optical (NLO) systems for device applications is critical to several fields. Optical computing, laser hardening, 3-dimensional data storage and remote sensing are just a few of the areas advanced by the characterization of new NLO systems. One promising venue for the development of these technologies is the nano-/meso-scale self assembly of viable chromophores into tunable aggregates. Here we present a method by which individual aggregates can be quantitatively imaged by two photon fluorescence near field scanning optical microscopy (NSOM).

two-photon, near-field, TPEF, TPA, NSOM, rhodamine B

Two-Photon Enhancement in Organic Nanorods†
Jeffery E. Raymond,‡ Guda Ramakrishna,‡ Robert J. Twieg,§ and Theodore Goodson III*,‡
Department of Chemistry, Macromolecular Science and Engineering, Gerald R. Ford School of Public Policy,
UniVersity of Michigan, Ann Arbor, Michigan 48109, and Department of Chemistry, Kent State UniVersity, Kent, Ohio 44242

The nonlinear optical response in one-dimensional organic nanorods of N,N-dimethyl-4-4((4-(trifluoromethylsulfonyl)phenyl)ethynyl)aniline (DMFSPA) was investigated to probe the long-range interactions in the nanocrystals on the microscopic level. Differences in the linear and nonlinear optical properties are shown for two different morphologies of these organic crystals as well as for the chromophore in solution. The optimized nanocrystalline suspension had more than an order of magnitude increase in the two-photon excited fluorescence when compared to the solution phase of DMFSPA at similar chromophore densities. The one and two-photon properties of the nanocrystals and bulk crystals are compared by near-field scanning optical multiscope imaging. The images also provide insights into the formation of the nanorods during initial crystallization, changes in the optical response of the system with time, and the viability of these and similar nanomaterials for consideration in solid-state organic device applications. In addition to providing an imaging regime by which to assess this and other solid-state nanocrystalline organics, our investigation provides a simple and elegant method for enhancing the nonlinear optical response of organic materials by transition to nanoscale morphologies, without the need for additional chemical modification or synthesis.

Near Field Scanning Optical Microscope NSOM Godwit - request a quote

Near Field Scanning Optical Microscope NSOM Godwit is a device that enables you to get the best spatial optical resolution using the near field scanning optical microscope (NSOM) principle

Near field scanning optical microscope (NSOM) and atomic force microscope (AFM) modes of operation
NSOM images with laser and lamp illumination
Commerciaand custom NSOM probes
Near field optica and luminescence images in photon counting mode
NSOM images in collection and illumination modes
Transmission and reflection NSOM configurations
20 nm optical resolution (Raleigh criteria for spatial resolution)
State-of-the-art optical microscope console: simultaneous sample and tip observation with long working distance objectives
Femtosecond and UV excitation
True single molecule detection
Godwit-uScope data acquisition and Godwit-FemtoScan image processing software
Ambient light protection with light-tight box

Fields of application:
Molecular spectroscopy, Fluorescence, Surface science, Thin films, Biology, Chemistry, Solid state physics, Nanotechnology, Material Science, Medicine, Education, Fiber optics


XY sample scanner
20 mm diameter central opening
Maximum scan size: 40 μm x 40 μm
Minimum scan step: 0.01 nm
Maximum image size: 1024 x 1024 pixels
Maximum XY sample travel: 10 mm x 10 mm (computer controlled)

Optical resolution
50 nm typical (depends on NSOM probe and sample under investigation)

Piezo-inertial Z stage with mounted NSOM probe
Maximum Z-travel: 9 mm
Z-scanning range: ±5 μm

Electronic control unit
XY stage electronics
Z stage electronics
Feedback (shear-force) electronics
Photon counting electronics
Lock-in amplifier
Connected to a computer via PCI card

Photon counter
Maximum photon counting rate: 5 x 107 cps
Dark counts: < 10 cps
Spectral response: 185 - 680 nm (185 nm - 850 nm optional)

Standard illumination sources
150 W quartz - halogen lamp
670 nm laser diode
532 nm solid state laser
488 nm Ar-ion or solid state laser
400 nm femtosecond laser

Recommended NSOM probes
633 nm single mode, Al - coated (50 - 80 nm aperture), 100 kHz resonance
400 nm single mode, Al - coated (<100 nm aperture), 32 kHz resonance

Optical unit with light-tight box: 350 (W) x 460 (D) x 460 (H)
Electronic control unit: 19” rack mountable or 170 (W) x 420 (D) x 200 (H)

request a quote - request a brochure - request a manual


AFM (topography) image of DNA (<3 nm thickness),
deposited onto a glass slide

Del Mar Photonics nano-imaging gallery

High resolution MFM image of Seagate Barracuda 750Gb Hard Drive, ST3750640AS.
130 nm Ag nanoparticles immobilized on the metal surface, 3.6x3.6 um scan
Magnetic structure of surface domains in Yttrium Iron Garnet (YIG) film
Atomic resolution on HOPG obtained with the 100 micron scanner
NSOM Fluorescence image of 100 nm - diameter TransFluoSpheres
Near-field optical image of 250 nm - diameter gold beads, deposited onto a glass slide
AFM (topography) image of DNA (<3 nm thickness), deposited onto a glass slide
Near-field optical image of 100 nm - diameter polystyrene beads, deposited onto a glass slide