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Ralph Sherman Becker

Bio: Ralph Sherman Becker is an academic researcher. The author has contributed to research in topics: Phosphorescence. The author has an hindex of 1, co-authored 1 publications receiving 304 citations.

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Book ChapterDOI
TL;DR: The chapter discusses FRET specifying the physical parameters that are available from a variety of fluorescence measurements, and some basic considerations and experimental procedures are described that are necessary to make reliable FRET measurements.
Abstract: Publisher Summary Fluorescence resonance energy transfer (FRET) is a spectroscopic process by which energy is passed nonradiatively among molecules over long distances. The “donor” molecule, which must be a fluorophore, absorbs a photon and transfer this energy nonradiatively to the “acceptor” molecule. Energy can be transferred over distances on the order of common macromolecular dimensions. This chapter discusses the applications of FRET to nucleic acid molecules conjugated to dye molecules; but in general, the donor-acceptor pairs can be free in solution, one or both bound to a macromolecule, or be an inherent part of the structure. The chapter discusses FRET specifying the physical parameters that are available from a variety of fluorescence measurements. In the chapter, some basic considerations and experimental procedures are described that are necessary to make reliable FRET measurements. It also discusses some difficulties that can arise in the experimental proceedings and data analysis and the sources of experimental error are pointed out.

766 citations

Journal ArticleDOI
TL;DR: The substitution of isoelectronic B-N units for C-C units in aromatic hydrocarbons produces novel heterocycles with structural similarities to the all-carbon frameworks, but with fundamentally different properties.
Abstract: The substitution of isoelectronic B–N units for C–C units in aromatic hydrocarbons produces novel heterocycles with structural similarities to the all-carbon frameworks, but with fundamentally alte...

441 citations

Journal ArticleDOI
TL;DR: A particular system is discussed--the cataractous lens--where UV photo-oxidation may play a role in the aetiology of the disease, and tryptophan-derived metabolites act as UV filters.
Abstract: Proteins comprise approximately 68% of the dry weight of cells and tissues and are therefore potentially major targets for photo-oxidation. Two major types of processes can occur with proteins. The first of these involves direct photo-oxidation arising from the absorption of UV radiation by the protein, or bound chromophore groups, thereby generating excited states (singlet or triplets) or radicals via photo-ionisation. The second major process involves indirect oxidation of the protein via the formation and subsequent reactions of singlet oxygen generated by the transfer of energy to ground state (triplet) molecular oxygen by either protein-bound, or other, chromophores. The basic principles behind these mechanisms of photo-oxidation of amino acids, peptides and proteins and the potential selectivity of damage are discussed. Emphasis is placed primarily on the intermediates that are generated on amino acids and proteins, and the subsequent reactions of these species, and not the identity or chemistry of the sensitizer itself, unless the sensitizing group is itself intrinsic to the protein. A particular system is then discussed – the cataractous lens – where UV photo-oxidation may play a role in the aetiology of the disease, and tryptophan-derived metabolites act as UV filters.

421 citations

Book
01 Jan 1999
TL;DR: The Origin of Fluorescence and its Applications as discussed by the authors The origin of fluorescence is discussed in detail in Section 2.3.2.1. Measurement of the Fluorescence Spectra.
Abstract: The Origin of Fluorescence. Environmental Effects on Fluorescence. Measurement of Fluorescence Spectra. Time and Phase Resolved Fluorimeters. Fluorescence Analytical Methods and Their Applications. Index.

330 citations

Journal ArticleDOI
TL;DR: The previous databases for 150 compounds have been expanded to encompass 339 compounds for which absorption spectra, fluorescence spectra and references to the primary literature have been included where available (552 spectra altogether).
Abstract: The design of new molecules for photochemical studies typically requires knowledge of spectral features of pertinent chromophores beginning with the absorption spectrum (λabs ) and accompanying molar absorption coefficient (e, m-1 cm-1 ) and often extending to the fluorescence spectrum (λem ) and fluorescence quantum yield (Φf ), where the fluorescence properties may be of direct relevance or useful as proxies to gain insight into the nature of the first excited singlet state. PhotochemCAD databases, developed over a period of 30 years, are described here. The previous databases for 150 compounds have been expanded to encompass 339 compounds for which absorption spectra (including e values), fluorescence spectra (including Φf values) and references to the primary literature have been included where available (552 spectra altogether). The compounds exhibit spectra in the ultraviolet, visible and/or near-infrared spectral regions. The compound classes and number of members include acridines (21), aromatic hydrocarbons (41), arylmethane dyes (11), azo dyes (18), biomolecules (18), chlorins/bacteriochlorins (16), coumarins (14), cyanine dyes (19), dipyrrins (7), heterocycles (26), miscellaneous dyes (13), oligophenylenes (13), oligopyrroles (6), perylenes (5), phthalocyanines (11), polycyclic aromatic hydrocarbons (16), polyenes/polyynes (10), porphyrins (34), quinones (24) and xanthenes (15). A database of 31 solar spectra also is included.

307 citations