One of the most powerful and versatile methods for studying molecules in solution is fluorescence. Crystallization typically takes place in a concentrated solution environment, whereas fluorescence typically has an upper concentration limit of approximately 1 X 10^-5 M, thus intrinsic fluorescence cannot be employed, but a fluorescent probe must be added to a sub population of the molecules. However the fluorescent species cannot interfere with the self-assembly process. This can be achieved with macromolecules, where fluorescent probes can be covalently attached to a sub population of molecules that are subsequently used to track the system as a whole. We are using fluorescence resonance energy transfer (FRET) to study the initial solution phase self-assembly process of tetragonal lysozyme crystal nucleation, using covalent fluorescent derivatives which crystallize in the characteristic P4₃2₁2₁ space group. FRET studies are being carried out between N-terminal lysine bound Texas Red as the donor and N-terminal lysine bound 5-(and-6)- carboxynaphthofluorescein as the acceptor.

We used Dynamic Light Scattering to study bio-molecule samples flown on the STS-95 mission, and processed in the Advanced Protein Crystallization Facility. The data represent for the first time characteristics of samples, which have been investigated at several stages in the processing chain: at the filling site, or the experimenter's laboratory, respectively, at the launch site before late access loading into the shuttle, and immediately upon return from orbit.

Near-field scanning optical microscope is a relatively new but very powerful technique for obtaining several metrological parameters at nanometer range spatial resolution. It is logical to think of deploying it into space applications like diagnostics of protein crystals growth under microgravity conditions. One may attempt to deploy existing instrumentation and expect some results. However, the existing technology and commercial instrumentation is tailored to ground based laboratory situations. Even in those laboratory conditions, the role of fluids (common in crystal growth), rough objects (such as a crystal under growth), etc. on the instrumentation is only recently under investigation. These aspects combined with the effects of reduced gravity environment will make the problem more complex. These technological challenges must be tackled for meaningful system operation in space. Since the microscopy concept has not yet been attempted to space, the actual problems are unknown. Nevertheless, based on current literature, some possible problems and potential solutions are described here. One may use the discussion for system modification/optimization during initial use of this kind of microscopy in space.

Protein crystal growth studies conducted on several Space Shuttle missions suggest that a low gravity environment is beneficial for crystal growth of many proteins. The reason for this improvement continues to elude investigators, although more recent studies suggest that its explanation may lie in the molecular growth mechanisms of the crystals. Understanding such processes will require powerful new techniques to be developed that can prove growth processes at the molecular level.

The focus of this paper is the characterization of electro- optic properties of single crystal thin films of organic material NPP grown by the plate-guided method. Characterization was performed using the longitudinal a.c. modulation technique. Half-wave voltage V_(pi ), figure-of- merit F, and electro-optic coefficient r₆₃ were estimated to be 3.24 kV, 0.98 X 10^-10 m/V and 25.8 MUL 10^-12 m/V respectively. We found that crystalline z-axis is off the normal to the plane of the film at an angle of 7⁰. We also proposed a transverse version of a thin film electro-optic modulator with low driving voltage, which is based on a single-arm thin film waveguide interferometer.

Silicon nanostructures present a new class of material systems that possess electrical and optical properties different from bulk and conventional thin film structures. We present a fabrication process for devices based on silicon nanopillars. The pillars were obtained by means of self-organized gold-chromium and polystyrene sphere masks and reactive ion etching of silicon. The evolution of pillar shape during reactive ion etching was observed by scanning electron microscopy and explained by combined effect of backscattering and polymerization.

Carbon nanotube tips (CNT) offer many advantages over the standard SFM probes, namely high aspect ratio, high resolution, durability, minimal tip or sample damage and, perhaps most important, tailoring. We demonstrate here the value of CNT as probes for surface metrology. Their high- aspect ratio enables profiling morphologies that are inaccessible to conventional probes. We report method for controlling the end-form of a nanotube bundle (mounted on a Si tip) so that a single nanotube protrudes from it. We did not observe any tip or sample wear over time with CNT probes, contrary to results with conventional probes. We also demonstrate that a combination of tuning forks and nanotubes can be used as probes for SPM.

The problem of measuring steep aspheres with high accuracy has not yet been generally solved. In this presentation, a particular sensor type is presented which can be used to measure the form of optically smooth surfaces with no restrictions as regards lateral extent or complexity. It is a curvature sensor which can be guided along the surface. Curvature is an intrinsic property of the artifacts, which is independent of its position and angular orientation.

An apparatus for measuring the topographies of complex surfaces with high accuracy by curvature scanning has been setup. For this purpose, a new type of curvature sensor that processes information from a relatively large area of the surface under test is moved along the surface. The principles advantages and a technical realization of this method referred to as large-area curvature scanning will be presented.

The development of a scanning near-field microscope that utilizes infrared absorption as the optical contrast mechanism is described. This instrument couples the nanoscale spatial resolution of a scanning probe microscope with the chemical specificity of vibrational spectroscopy. This combination allows the in situ mapping of chemical functional groups with subwavelength spatial resolution. Key elements of this infrared microscope include: a broadly tunable infrared light source producing ultrafast pulses with a FWHM bandwidth of 150 cm^-1, an infrared focal plane array-based spectrometer which allows parallel detection of the entire pulse bandwidth with 8 cm^-1 resolution, and a single mode fluoride glass fiber probe which supports transmission from 2200 to 4500 cm^-1. A novel chemical etching protocol for the fabrication of near-field aperture probes is described. Infrared transmission images of a micropatterned thin gold film are presented that demonstrate spatial resolution of (lambda) /8 at 2900 cm^-1, in the absence of artifacts due to topography induced contrast. Images of thin film polymer blends and nanocomposites acquired in the C-H stretching region are used to benchmark the chemical imaging capabilities of this microscope, focusing particularly on the absorption sensitivity of the spectrometer.

Scanning near field optical microscopes provide access to highly resolved optical and topographical surface properties. The resolutions that can be achieved are better than 100 nm. However, the quality of the optical fiber tip is of decisive importance. Because the production process of pulled and coated glass fiber tips is still highly empirical and error-prone, a technique would be useful to determine the tips' quality before they are shipped to the user or mounted in the microscope.

In recent years, there have been intense efforts in the study of the physical principles and applications of the scanning near-field optical microscope. Extensive theoretical analyses, numerical simulations, and experimental investigations have been conducted. It is demonstrated that image resolution and contrast depend not only on the aperture size of the probe and the reflection/transmission of the sample, but also on other parameters and experimental conditions. Accordingly, appropriate characterizations of image resolution and systems performance specifications are needed to enable the construction of more reliable and reproducible systems as well as inter-laboratory comparison. In this paper, recent advances in the systems design concepts for different applications will be reviewed, and possible standardization schemes for the characterization of image resolution and the specification of system performance will be proposed.

A comparison between PSTM and A-SNOM in resolution, contrast and optical efficiency is discussed. The order of magnitude roughly estimated shows that PSTM is must better than commercial A-SNOM.

In this paper near-field distributions of nanometric apertures, the uncoated and metal-coated fiber-optic probes used in near-field scanning optical microscope are characterized by the method of finite-difference time- domain. Moreover, to give a clear view of the influence of parameters, say, the taper angle ((alpha) ), the aperture diameter (d), the refractive index of the fiber-optic (n) and the sample (ns), the tip-sample separation (z), on the throughput of metal-coated fiber-optic probes, we investigated it in detail.

We propose to fabricate GaAlAs/GaAs multi-layer microtips for scanning near-field optical microscope using the anisotropic etching. The etching was performed in a solution of H₃PO₄:H₂O₂:H₂O, operating at the temperature of 10 degree(s)C. We obtained the pyramid-shaped microtips with four etched facets and with a radius of curvature at the apex lower than 50 nm.

We designed Apo 100X NA 1.65 and Plan Apo 60X NA 1.45 objective lenses. When we use three lenses for water- immersed specimens, the marginal angle available for the total internal reflection becomes larger compared with NA 1.40 objective lens. Therefore, the alignment of the laser beam to the objective lens becomes very easy. We also designed the TIRFM illuminator. A single mode fiber is connected between the laser and illuminator. The laser beam is conducted through the fiber and supplied to the illuminator with a pre-adjusted positioning. Almost no additional alignment of illumination light is necessary.

The R(v)-representation of the low-frequency Raman spectrum was used to investigate the low-frequency Raman spectrum of water. The advantages of using reduced representations in low-frequency Raman studies to display water structure are discussed. Tetrahedrically hydrogen bonded water molecules showed a characteristic low-frequency band with a peak maximum around 180 cm^-1. O-18 and O-17 isotopic substitution revealed that the corresponding vibrational mode mainly involves displacements of the oxygen atoms, but no significant hydrogen motion. This mode can be used to monitor the existence of water with a bulk-like structure in biological macromolecular materials. To test its applicability NIR-FT-Raman spectroscopy was used in studies of biopolymers in order to avoid fluorescence.

In this work, Raman spectroscopy was investigated as a tool for monitoring glutamate levels in the eye. Glutamate is a by product of nerve cell death, and is an indicator of macular degeneration. Raman spectra was from ex vivo porcine eyes was investigated, with glutamate injected into the eyes to simulate disease conditions. The Raman spectra from the native eye was dominated by the lens. However, an optical system was designed to optimize collection of signal from the vitreous and reduce the background lens signal. The molecular signature of glutamate was detectable in the Raman spectra by this system.

The deformation micromechanics of single-walled carbon nanotube (SWNT) particulate nanocomposites has been studied using Raman spectroscopy. SWNTs prepared by two different methods (pulse-laser and arc-discharge) have been used as reinforcement for a polymer matrix nanocomposite. The carbon nanotubes exhibit well-defined Raman peaks and Raman spectroscopy has been used to follow their deformation. It has been found that for all nanocomposite samples deformed, the G' Raman band shifted to a lower wavenumber upon application of a tensile stress indicating stress transfer from the matrix to the nanotubes and hence reinforcement by the nanotubes. The behavior has been compared with that of high-modulus carbon fibers and has been modeled using orientation factors suggested initially by Cox. In this way it has been possible to demonstrate that the effective modulus of SWNTs dispersed in a composite could be up to 1 TPa.

The evolution of off-resonant and resonant Raman scattering spectra of cis and trans nanopolyacetylene (NPA) with change of frequency and intensity of incident laser light was studied. It was found that laser irradiation with wavelength 514.5 nm in process of Raman scattering spectra recording is accompanied by effective cis trans isomerization of approximately 50% cis - 50% trans NPA-PVB blend. The results obtained allow assuming that NPA in the initial compositions is a mixture of two types of nanoparticles.

GaN thin film materials, un-doped, Si- and Mg-doped, have been grown on c-sapphire substrates by low pressure metalorganic chemical vapor deposition, and have been characterized by micro-Raman scattering ((mu) -RS) and micro- photoluminescence ((mu) -PL) spectroscopy. Basic Raman scattering modes, and in particular, their variations have been observed with the laser incident on the cross section of a few micron thick GaN film. Raman line shape analysis on the E₂ mode is presented, based upon the spatial correlation theoretical model. Through the theoretical modeling of the LO-phonon-plasmon coupling, the free carrier concentration can be determined via Raman measurements and curve fitting. Using a newly designed and developed UV Raman-PL microscope system, room temperature PL and its variation with the SiH₄ doping level for a series of n- type GaN epitaxial materials have been studied. Combined UV (mu) -RS-PL spectra from p-type GaN are also investigated.

The microstructures of three different silicon carbide (SiC) fibers produced by CVD (chemical vapor deposition) have been examined in detail using Raman microscopy. Raman spectra were mapped out across the entire cross-sections of these silicon carbide fibers using an automated x-y stage with a spatial resolution of 1 micrometers . The Raman maps clearly illustrate the variations in microstructure in such types of silicon carbide fibers. It appears that the SCS-type fibers contain carbon as well as SiC whereas the Sigma 1140+ fiber also contains free silicon. Furthermore, the differences in the detailed structures of the carbon and silicon carbide present in the fibers can also be investigated. Raman microscopy is demonstrated to be a very sensitive technique for characterizing the composition and microstructure of CVD silicon carbide fibers prepared using different processing conditions.

High temperature phase transition of (beta) -BaB₂O₄ (BBO) and K₃Li_12-xNb_5+xO_15+2x (KLN) crystals are studied in detail by using high temperature Raman scattering. The temperature increasing of the crystals due to the increasing of the incident laser power during the frequency doubling process and the influence on the structure of the crystals are analyzed. It is the first time that the relationship between the phase transition and the frequency doubling is studied by high temperature Raman spectra. The opinion of phase transition having effect on frequency doubling is given out.

These portrait miniatures on ivory were analyzed by Raman microscopy to determine the identity of tiny, white crystals which occur under, within, or on top of their paint layers. In each case the crystals were identified as magnesium hydrogen phosphate trihydrate, newberyite (MgHPO₄.3H₂O). Small, white crystals which grow on the inner surface of ivory tusks were also identified as newberyite by means of Raman microscopy. Thus, it is concluded that the tiny, white crystals occurring on the portrait miniatures on ivory almost certainly originate from the ivory substrate. Resonance Raman spectroscopy using 632.8 nm excitations were found to be a sensitive probe for the detection of the blue pigment, indigo, even when it occurs in pigment mixtures on paintings. Raman microscopy was also used in analyze a fragment of opaque red Assyrian glass, dating from around the 9th-8th centuries BC, an opaque red Iron Age glass stud, dating from around the 1st century BC, and three opaque yellow Anglo-Saxon glass beads, dating from the 6th century AD.

Micro-Raman spectroscopy is excellently suited for the investigation of artifacts, as it is a fast and nondestructive method that can be applied for the identification of a whole range of materials. This identification depends on spectrum interpretation and on the comparison of the unknown spectrum with an extended library. Another advantage of Raman spectroscopy is that spectra can be recorded by direct analysis of the artifact or of micro- samples. The coupling of the spectrometer with a microscope reveals a high spatial resolution, which allows spectra of individual grains with dimensions down to 1 micrometers to be recorded. Therefore a non-destructive micro-sampling method can be used. Raman spectroscopy can be applied for several types of materials and is applicable to ancient pieces as well as modern objects of art. An example is given on the Raman spectroscopic examination of miniatures from a medieval book of hours and of a 19th Century porcelain card.

The newest gemstone treatment concerns brownish diamonds of type IIa. These can be improved to near colorless by an enhancement process developed by General Electric, USA, using high temperature and pressure. A comparison of Raman spectroscopic features in the visible area (luminescence bands) of both treated and untreated colorless diamonds is given. Finally, examples of artificially colored peals and corals and their detection with Raman spectroscopy are shown.

Near-field Raman spectroscopy can be used to obtain images with both chemical specificity and the subwavelength spatial resolution of near-field scanning optical microscopy. In the absence of signal intensification factors, such as `surface enhancement' or electronic resonance in the specimen, Raman scattering suffers from a small cross section ((sigma) equals 10<sup>-28</sup> cm<sup>2</sup> to 10<sup>-31</sup> cm<sup>2</sup>). Since most reports of Raman-NSOM to date involve exploitation of a specimen-specific intensification, an assessment of the general applicability of Raman-NSOM to a wider variety of `un-enhanced' samples is of great interest. We report here on several approaches to increasing the sensitivity of near- field Raman spectroscopy that do not rely on specimen properties. The use of chemically etched aperture probes as an illumination source has been investigated and compared to probes fabricated by the traditional heat and pull method.

Elastic properties of thin supported films can be derived from the dispersion relations of surface acoustic waves (SAWs), which depend on the properties of the films themselves. Among the techniques for the measurement of SAW velocities surface Brillouin scattering (SBS) of visible light probes SAWs at the shorter wavelengths (around 0.5 micrometers ), allowing resolution down to nanometric films. Since SAW velocities can be computed as function of elastic constants and mass density of both the film and the substrate, of film thickness and of wavevector, the elastic properties can be obtained by fitting the computed velocities of the measured ones. Namely, if film thickness and density are independently measured, e.g. by X-ray reflectivity and X-ray diffraction, the elastic constants of the film can be derived by a Generalized Least Squares estimator, with corresponding confidence intervals. Accurate derivation of elastic constants requires highly accurate SAW velocity measurements. Some examples are considered in detail: diamond-like carbon films on silicon substrate and titanium silicide films, showing that elastic constants of thin films can be determined by SBS measurements with precisions ranging from reasonable to very good.

Impulsive stimulated scattering is utilized to study the acoustic and mechanical properties of both transparent molecular solids and opaque crystalline metal surfaces. Scattering measurements have been performed on oriented molecular crystals under high pressure conditions in a diamond anvil cells. The ISS technique offers an accurate and robust method of obtaining bulk and surface acoustic velocities of molecular and metallic crystals under extreme conditions without the need for physical contact with the sample. Specifically, directionally resolved impulsive thermal Brillouin scattering has been used to obtain acoustic velocities for oriented crystals of ice VI and ice VII in a high pressure diamond anvil cell. The elastic constants determined from these measurements compared favorably with classical Brillouin scattering results. Impulsive stimulated scattering (ISS) has also been used to obtain the directional dependence of the surface acoustic wave (SAW) velocity on oriented crystal surfaces of metals such as aluminum (111) and nickel (100). The orientationally dependent ISS results for Ni (100) are compared with classical Brillouin scattering measurements, as well as surface acoustic wave calculations utilizing bulk elastic constants.

(alpha) -LiIO₃ crystal is grown by the constant temperature evaporation method. Brillouin scattering experiment is carried out to study the elastic properties of the crystal (alpha) -LiIO₃. We obtain all of six elastic constants of the crystal (alpha) -LiIO₃ by using two cubic samples. As a result the obtained elastic constants are similar to the others' results. From the obtained elastic constants it is possible to construct slowness curves.

At high levels of optical excitation, local coherence in particles or ordered domains within mesoscopically disordered materials can lead to second harmonic emission whose temporal signature characterizes the decay kinetics of the excited state population. Examples of such systems include colloids, cell and membrane suspensions, and many plastics, glasses and other modern materials. The effect is prominent in frequency regions where the second order optical nonlinearity is dominated by transitions involving one particular electronic excited state, and where a two- level model closely models the optical response. With ultrafast pulsed excitation of sufficient intensity to elicit the onset of saturation, second harmonic emission on throughput of a subsequent probe beam exhibits a characteristic decay and recovery. Detailed calculations show that such features also arise in systems whose optical response involves more than two levels.

Sodium 4-Nitrophenolate dihydrate (NPNa), an optically highly non-linear material, has been synthesized in methanol in form of 6 X 9 X 6 mm³ transparent single crystals. X-rays precession measurements confirmed the values of the unit cell parameters of symmetry Ima2 equals C²²_2v. Polarized Raman scattering experiments have been performed, as a function of temperature, between 10 and 300 K in a wide spectral range. We present the results in the low wavenumber region [10 - 200] cm^-1 in which we studied in detail four peaks: 57, 55, 178 and 189 cm^-1 at 20 K. The two former are lattice modes, the two latter are hydrogen bond vibrations corresponding to two different O...O distances, 2,00 angstroms and 2.789 angstroms respectively. In addition, a relaxor behavior has been observed and analyzed in relation with a possible disorder in the substance. The analysis of the behavior versus temperature of the wavevector, damping and intensity of the three vibrational modes provide new results with respect to the dynamical properties of the substance, compared to its structure.

Micro-Raman spectroscopy is an important molecular spectroscopic technique for the non-destructive examination of objects of art. In this work, Raman spectra of a number of Azo-pigments are presented, which are important artists' pigments in contemporary artifacts. The Azo-pigments, being a group of cheap pigments with good painting properties, form an important subgroup of pigments that became available to the artists at the end of the 19th and the beginning of the 20th century. A classification for these Azo-pigments is presented, which is based on their chemical properties, reflected in their molecular Raman spectrum. It is shown that a close spectral examination can help in assigning the unknown pigment to a class of pigments and thus assist in the identification of the painting material.

Tunable nanostructures can be patterned in Ga[Al]As heterostructures with an atomic force microscope (AFM). Oxidizing the GaAs cap layer locally by applying a voltage to the AFM tip leads to depletion of the electron gas underneath the oxide. Here, we describe this type of AFM lithography as a tool to fabricate tunable nanostructures. Novel technological options are discussed, and the electronic properties of the resulting confinement is characterized. As an example for the versatility of this technique, we present electronic transport measurements on quantum wires.