Comparison of Discrete and Continuous Motion in Scanning Probe Microscopy Monitored via Confocal Raman Microspectroscopy

Confocal Raman imaging is a relatively new analytical technique that combines the strengths of Raman microspectroscopy and confocal optics. The images collected by the microscope are obtained by monitoring specific bands in the Raman spectra that are collected at many points in a sample, with the number of spectra usually numbering in the hundreds or thousands. Some commercially available systems acquire data while the sample is continuously moving with respect to the microscope objective. The distance that the stage moves during a single acquisition is a parameter that can be set prior to data acquisition. Data in this report was acquired with both a static and continuously moving sample for comparison, utilizing the 520 cm−1 Si phonon of a silicon wafer to monitor an edge. Scattering collected from each discrete step, i.e., no motion during spectral acquisition, showed excellent precision of location, but a loss in resolution was observed as the pixel size was increased beyond the maximum theoretical resolution of the instrument. A continuously moving stage contributed to erroneous position data as the pixel size was increased beyond the maximum theoretical resolution of the instrument.