No abstract

The use of Raman microspectroscopy to depth profile multi-layered polymer laminates is becoming increasingly popular. However, the results are generally degraded by aberrations introduced by the change in refractive index at the air/sample interface. Recent research has suggested that the use of an immersion oil and suitable objective can reduce this effect. This study evaluates this proposal by comparing depth profiling results on a multi-layer poly(styrene)/poly(methylmethacrylate) (PS/PMMA) laminate polymer from both dry metallurgical objectives and immersion objectives (used in combination with an oil of suitable refractive index). The immersion technique enabled successful depth profiling to the full working distance of the objective (100 microm), showing clear and distinct variations in 11 different layers within the laminate; a dry metallurgical objective used for comparison achieved poor resolution of only two layers. This is the first demonstration of depth profiling within a polymer laminate to this depth. The depth profiling results are compared to results obtained by sectioning the PS/PMMA sample after setting it in resin.

Raman spectroscopy is steadily growing in importance in the industrial analytical laboratory. The nature of the equipment, its ease of use and its cost are making the method more acceptable to non-experts. This paper illustrates the capabilities of a recent commercialized Raman system which fulfils the criteria of ease of use, speed and low cost. The system is designed for Raman microscopy and uses a single spectrograph and CCD detector. The combination provides confocal microscopy, high throughput and optimum sensitivity, to the extent that it only requires the use of a low-powered laser to provide high-quality spectral data. The additional feature of direct Raman imaging is seen as being beneficial in the industrial environment in that it provides spatial information over large surface areas quickly and without the need for excessive amounts of data processing. The performance of the instrument is illustrated with applications taken from the industrial environment.