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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
Volume848
Pagination61-66
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
Abstract

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.

DOI10.1016/j.aca.2014.07.040
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