荧光和荧光光谱.ppt

Fluorescence & Spectroscopy 荧光和荧光光谱?良好的天平可测出 10 -5克的物质,微量化学分析可测出 10 -9克的物质,光谱分析可测出 10 -10克的物质,荧光分析可测出 10 -11~10 -12克物质, 一般的放射分则可测出 10 -18 ~10 -19克的物质?(请参见:任时仁编著“生物学中的放射必核技术”,北京大学出版社, 1997 : P173 ; ?潘中允主编“简明核医学”,北京医科大与中国协和医科大联合出版社, 1990 : P139) 。?因此,荧光分析法和放射分析法,尤其是后者,是目前最好的可用于对超微量物质进行高灵敏性测定的分析方法。 10 -18 10 -16荧光光谱法特点灵敏度高、选择性强、用样少、方法简便以及能提供较多的物理参数等优点。用途广泛, 如可用于研究溶液中蛋白质构象。 By Felix A. Carroll, Perspectives on Structure and Mechanism anic chemistry Brooks/Cole pany, 1998 KASHA RULE Polyatomic molecular entities luminesce with appreciable yield only from the lowest excited state of a given multiplicity. There are exceptions to this rule. KASHA-VAVILOV RULE The quantum yield of luminescence is independent of the wavelength of exciting radiation. There are exceptions to this rule. Anomalous Fluorescence Patterns in Corals We have noticed several kinds of anomalous patterns in corals that show up clearly in fluorescence but are not visible under white-light illumination. These include: ? bright or dark patches within areas of more uniform fluorescence ? isolated patches of fluorescent color ? color patterns that are only seen in fluorescence The significance of these effects pletely unknown, but they almost certainly point to underlying differences in internal chemistry. White-light (left) and fluorescence (right) photographs of a coral, Roatan , Honduras. Note the yellow-fluorescent area in the photograph on the right that is not evident in the other image.