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High angular-resolution automated visible-wavelength scanning angle Raman microscopy

TitleHigh angular-resolution automated visible-wavelength scanning angle Raman microscopy
Publication TypeJournal Article
Year of Publication2014
AuthorsLesoine, MD, Bobbitt, JM, Zhu, SB, Fang, N, Smith, EA
JournalAnalytica Chimica Acta
Date Published10
Type of ArticleArticle
ISBN Number0003-2670
Accession NumberWOS:000342169900007
Keywordsadsorption, diblock copolymer, field, films, P3HT, Raman instrumentation, Raman spectroscopy, reflection, scattering, spectra, Spectroscopy, surface, Thin film measurement, wave, Waveguide

A scanning angle (SA) Raman microscope with 532-nm excitation is reported for probing chemical content perpendicular to a sample interface. The instrument is fully automated to collect Raman spectra across a range of incident angles from 20.50 to 79.50 degrees with an angular spread of 0.4 +/- 0.2 degrees and an angular uncertainty of 0.09 degrees. Instrumental controls drive a rotational stage with a fixed axis of rotation relative to a prism-based sample interface mounted on an inverted microscope stage. Three benefits of SA Raman microscopy using visible wavelengths, compared to near infrared wavelengths are: (i) better surface sensitivity; (ii) increased signal due to the frequency to the fourth power dependence of the Raman signal, and the possibility for resonant enhancement; (iii) the need to scan a reduced angular range to shorten data collection times. These benefits were demonstrated with SA Raman measurements of thin polymer films of polystyrene or a diblock copolymer of polystyrene and poly(3-hexylthiophene-2,5-diyl). Thin film spectra were collected with a signal-to-noise ratio of 30 using a 0.25 s acquisition time. (C) 2014 Elsevier B.V. All rights reserved.

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