单词	Fraunhofer, Joseph von
释义	Joseph von Fraunhofer /ˈfraʊnˌhəʊfə / /ˈfraʊnˌhoːfɐ/ (1787–1826), German optician and pioneer in spectroscopy. He observed and mapped the dark lines in the solar spectrum (Fraunhofer lines) which result from the absorption of particular frequencies of light by elements present in the outer layers; these are now used to determine the chemical composition of the sun and stars.In 1854 Stokes theorised an explanation of the Fraunhofer lines in the solar spectrum.... The roots of absorption spectroscopy can be traced to 1802, when the English chemist William Hyde Wollaston observed what later became known as the Fraunhofer lines - the many dark lines seen in the spectrum of sunlight. We are shown clearly the bands of colors, but Rowland's more exacting analysis would spread this spectrum over sixty feet, revealing also the Fraunhofer lines: hundreds of dark lines interspersed throughout the spectrum.
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