Special Issues-06-01-2006

Recent progress in photonic crystal design is transforming surface-enhanced Raman spectroscopy (SERS) from a research tool into a powerful new analytical technique. High sensitivity can be achieved due to the enormous amplification of the Raman signal of molecules in contact with nanostructured metal surfaces. This article highlights the performance of SERS substrates for a range of applications, illustrating the versatility of the technology, as well as future directions.

Outstanding stray light rejection performance of a triple-spectrometer system is demonstrated. Low-frequency Raman spectra of solid powder samples, including Stokes-AntiStokes Raman data, as low as 5 cm-? from the excitation line are presented.

Chemical images of polystyrene beads on silicon acquired using Raman mapping and image processing are reviewed. The effects of the objective on the quality of the final image, particularly its magnification and numerical aperture, and the step size of the map, are discussed as well.

Advances in Raman spectroscopy and imaging generate large amounts of information pertaining to the chemical and physical composition of materials. The distillation of meaningful and useful information from such quantities of data can be challenging. New image analysis software combined with powerful chemometric techniques permit an analyst to perform rapid calibrationless and quantitative analysis and discover features easily overlooked using less rigorous methods. This article describes mapping and analysis of a painkiller tablet using a dispersive Raman microscope and accompanying software.

Special Issues

In conventional designs for dispersive Raman spectrometers, there is a tradeoff between spectral resolution and light throughput. A new design approach using Multimodal Multiplex (MMS) technology provides approximately 12x the throughput of a conventional slit-based system with no compromise in spectral resolution. This translates into a signal-to-noise advantage of greater than 3.5x for equivalent measurement times. In addition, the wide area aperture is ideally suited to large sample spot illumination, which yields measurements that are more representative of the bulk of the sample being analyzed.

Carbon nanotubes are unique nanostructures with remarkable mechanical and electrical properties. Due to their tremendous potential for future innovations, great efforts are made to characterize these structures. In the following study, carbon nanotubes were investigated with Confocal Raman Microscopy and Atomic Force Microscopy using only one single instrument.