Refractive-index anisotropy and optical dispersion in films of deoxyribonucleic acid

Autor: James G. Grote, Anna Samoc, Andrzej Miniewicz, Marek Samoc
Rok vydání: 2007
Předmět:
Zdroj: Journal of Applied Polymer Science. 105:236-245
ISSN: 1097-4628
0021-8995
DOI: 10.1002/app.26082
Popis: Received 12 May 2006; accepted 29 July 2006DOI 10.1002/app.26082Published online in Wiley InterScience (www.interscience.wiley.com).ABSTRACT: We have determined the refractive indicesin the directions parallel and perpendicular to the surfaceplane of films of deoxyribonucleic acid (DNA) and theirwavelength dispersion. These parameters are fundamen-tal for understanding the properties of waveguidingstructures containing DNA-based photonic materials. Theorientation of DNA molecules in films and their opticalproperties are sensitive to the film fabrication and envi-ronmental conditions influencing the structure. Prismcoupling measurements show ambient-humidity-relatedchanges in the refractive index, birefringence, and anisot-ropy of the alignment of the DNA molecules in the filmsstudied. These films were 0.5–5 mm thick, were preparedby both spin coating and casting from aqueous solutionscontaining 0.1–3 wt % DNA, and were measured inambient air with relative humidities of 37–58%. Theoptical properties of the films and the orientation of theDNA molecules are discussed with respect to the mech-anism for the formation of the polymer liquid-crystallinephases during film deposition. The dispersion of the re-fractive indices in films of native DNA has been derivedfrom interference fringes in absorption and reflectionspectra in the wavelength range of 350–2700 nm throughthe fitting of the positions of the fringes with the Sellme-ier dispersion formula in combination with the prismcoupling data.
Databáze: OpenAIRE
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