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PHOTOELECTRON QUANTUM YIELD SPECTRUM AND PHOTOELECTRON MICROSCOPY OF β‐CAROTENE
Author(s) -
Brown Hugh M.,
Kingzett Paul C.,
Griffith O. Hayes
Publication year - 1978
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1978.tb07627.x
Subject(s) - x ray photoelectron spectroscopy , arachidic acid , quantum yield , carotene , chemistry , photoemission spectroscopy , analytical chemistry (journal) , materials science , optics , physics , nuclear magnetic resonance , fluorescence , chromatography , biochemistry , fatty acid , organic chemistry , palmitic acid
—The absolute photoelectron quantum yield spectrum for β‐carotene in the wavelength range 180–230 nm is reported. β‐Carotene is very photoemissive over this wavelength region with photoelectron quantum yields on the order of 2 × 10 ‐ ‐ 3 electrons per incident photon at 180 nm, 4 × 10 ‐ ‐ 4 at 210 nm, and 3 × 10 ‐ ‐ 5 at 230 nm. At wavelengths longer than 240 nm, β‐carotene photoemission dropped off monotonically with increasing wavelength. The photoelectron quantum yield spectrum of β‐carotene is very similar to that of chlorophyll a . A photoelectron micrograph of β‐carotene deposited on a thin layer of the fatty acid arachidic acid demonstrates the marked photoemission contrast between β‐carotene and membrane lipid. Photoelectron micrographs of samples with β‐carotene and Chl a in the same field show that prolonged (1 h) illumination in vacuo causes β‐carotene to markedly fade while leaving the Chl a photoemissive. This differential bleaching of β‐carotene may allow it to be distinguished from Chl in high magnification photoelectron micrographs of photosynthetic membranes.