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Water-soluble poly(ethylene oxide-block-methacrylic acid) (P(EO-b-MAA)) and poly(ethylene oxide-block-styrene sulfonic acid) (P(EO-b-SSH)) diblock copolymers were used to control the particle morphologies, sizes and size distributions of zinc oxide precipitated from aqueous solution. With P(EO-b-MAA) copolymers, hexagonal prismatic particles form. Their sizes and size distributions depend on the degrees of polymerization of the blocks. With P(EOb-SSH) copolymers, the particle shape reminds one of a "stack of pancakes". These samples have narrow size distributions, regardless of the degrees of polymerization of the P(EO-b-SSH) copolymers. All crystals have a central grain boundary assigned to twinning. There is evidence for P(EO-b-MAA) copolymer adsorption onto the basal planes of the zinc oxide particles, whereas with P(EO-b-SSH) also an adsorption onto the side faces seems possible. The polymers are incorporated to some extent in the crystals and the amount of the polymer incorporated depends on the initial polymer concentration of the reaction solution.

The structural properties of both nanodiamond particles synthesized by detonation and the products of their transformation into carbon onions via vacuum annealing at 1000 and 1500°C have been studied using high-resolution transmission electron microscopy (HRTEM), electron energy-loss spectroscopy, x-ray diffraction (XRD), small-angle x-ray scattering (SAXS), and Raman spectroscopy. The advantages of UV Raman spectroscopy over visible Raman spectroscopy for the analysis of these carbon nanomaterials are demonstrated. It was found that the synthesized nanodiamond particles have a composite core-shell structure comprising an ordered diamond core covered by a disordered (amorphous) outer shell formed by the mixed sp2∕sp3 bonding of carbon atoms. The observed structure of the nanodiamond particles are comparable with the structure of the bucky diamond clusters comprising a diamond core and a reconstructed surface which stabilizes the cluster at the average diameter of ∼30Å, as predicted recently from theoretical studies. Assuming a spherical shape for the particles and employing a two-step boundary model of electron density distribution developed in this work to describe the SAXS patterns produced by the core-shell structure of the nanodiamond particles, it was evaluated that the average diameter of the core is ∼30Å and the average thickness of the shell is ∼8Å; values which are in agreement with results obtained from HRTEM and XRD measurements. A discrepancy between these results and average diamond crystallite size obtained from Raman spectra by applying the phonon confinement model (35–45Å) is discussed. It is hypothesized from analysis of broadening of the XRD diamond peaks that at the nanoscale under influence of the particle shape, which is not strictly of a cubic (or spherical) symmetry, a slight hexagonal distortion of the cubic diamond structure appears in the nanodiamond particles. The transformation of the nanodiamond into carbon onions proceeds from the amorphous outer shell of the particles inwards towards the particles’ diamond core. UV Raman spectroscopy effectively senses the initial stage of the transformation revealing a reconstruction of the mixed sp2∕sp3 bonding of carbon atoms located in the outer shell, into sp2-bonded carbon atoms similar to those in nanocrystalline graphite. It is shown that intershell distance in carbon onions formed from nanodiamonds depends on the temperature of the transformation and relates to the linear thermal expansion coefficient of the graphite structure along the stacking direction of the graphene layers (the c axis). In accordance with SAXS results, there is evidence for an increase of the average particle size of the synthesized nanodiamond [48(3)Å] after transformation into carbon onions [58(10)Å].

We have developed a model to describe the effect of refraction through a planar interface on the collection efficiency and depth of focus when performing confocal Raman microspectroscopy. The planar interface introduces spherical aberration, which can substantially degrade the performance of the microscope, especially for large-numerical-aperture microscope objectives. This spherical aberration will increase the range of focal depths spanned by the paraxial and marginal rays of the illuminating laser beam within the sample. In the collection path, it will also distort the scattering volume defined by the confocal aperture; this results in a dramatic fall in the collected light intensity with increasing depth. We demonstrate that there is an optimum numerical aperture for collected light intensity at a given depth. The prediction of this theoretical model is compared to empirical results obtained by mapping the stress distribution within the diamond anvil of a high-pressure cell. Both the collected Raman intensity and the effective depth of focus are compared to the predictions from the theory.

The relatively well-known mirror reaction method of forming silver films has been used to produce substrates for surface enhanced Raman scattering (SERS). The simple and convenient method produces a thin metal film on silicon that shows an order of magnitude superior surface enhancement properties when compared to a conventional SERS substrate made by vacuum evaporation. Of particular interest is that the method is ideal for coating atomic force microscope probes for apertureless scanning near-field spectroscopy which is usually made difficult by the damage caused by evaporative coating and annealing.

The vibrational modes of the sp3 sites in tetrahedral amorphous carbon (ta-C) thin films are revealed directly using ultraviolet Raman spectroscopy at 244 nm excitation and are shown to produce a Raman peak centered around 1100 cm−1. In addition, the main Raman peak associated with sp2 vibrational modes is shifted upward in frequency by 100 cm−1 relative to its position in spectra excited at 514 nm. The spectra are interpreted in terms of the bonding in ta-C.

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