Mechanism Of Photochemistry Research Articles

Resolving Component Overlap in Multiwavelength Kinetic Spectroscopy: Application to Raman Scattering from Intermediates in Triplet‐State Photoreactions

Abstract— Understanding of reaction mechanisms in photochemistry is advanced both by kinetic measurements to determine rates of reaction and by spectroscopic studies of the structures of precursors and photoproducts. When kinetics and spectroscopy are combined in a time‐resolved, multiwavelength spectroscopic measurement on a reacting system, spectra and structures of intermediates can also be determined. In this paper, the application of multidimensional least‐squares and factor analysis techniques for resolving overlapped spectra from intermediates in photochemical kinetics are discussed. The methods are employed specifically to resolve Raman spectra of intermediates in triplet‐state photoreactions. By varying excitation intensity, spectra of excited‐triplet states are resolved from ground states and solvent. By varying the concentration of a triplet quencher in the sample, the Raman spectrum of a sensitizer excited state (benzophe‐none) can be resolved from those of acceptor‐triplet states or radical photoproducts. Applications of these concepts in other areas of photochemical kinetics are addressed.

Mechanisms in photochemistry on metal surfaces

Fundamental mechanisms for photochemistry at metal surfaces are discussed. Experiments probing these mechanisms are presented for molecular oxygen adsorbed on palladium(111). In particular the dependence of these processes on photon energy and its relation to hot carrier dynamics is discussed.

Photodynamics on Surfaces Revealed by Laser Studies

AbstractFundamental mechanisms for photochemistry at metal and semiconductor surfaces are discussed. Experiments probing these mechanism are presented discussed for molecular oxygen adsorbed on palladium(111). Isotope effects in photodesorption and photodissociation are shown to provide insights into the excitation transfer mechanisms and the probability of nonquenching events.

A conical intersection mechanism for the photochemistry of butadiene. A MC-SCF study

The excited state (2 1 Ag) reaction paths involved in the photochemical transformations of butadiene have been studied via ab initio MC-SCF methods. It is demonstrated that the reaction funnel assumes the form of a conical intersection region where the ground (1 1 Ag) and first excited (2 1 Ag) potential energy surfaces are degenerate. This mechanism is consistent with experimental results for the photochemical isomerization and is also consistent with the observed absence of fluorescence from the 2 1 Ag state. Thus the currently accepted mechanisms for butadiene photochemistry which involve radiationless decay at avoided crossing minima need to be replaced with a model that involves fully efficient return to the ground state via a conical intersection

Fundamental mechanisms of surface photochemistry

The fundamental mechanisms of photochemistry of molecules adsorbed on solid surfaces are revealed from results obtained by a combination of optical techniques, surface probes, and gas phase analysis. While photon-induced processes similar to those in the gas and liquid phase are observed for the adsorbed molecules, the presence of the substrate introduces important channels for energy exchange, dissipation, and adsorbate photochemistry.

Photoracemization/substitution of optically active rhodium(III) complexes, cis-L-[Rh(en)2(OH)Xn+

The photochemistry of cis-L-Rh(en)/sub 2/(H/sub 2/O)(OH)/sup 2 +/ and cis-L-Rh(en)/sub 2/(OH)/sub 2//sup +/ in aqueous solution is reported. Irradiation at 313 nm results in a photoracemization quantum yield of 0.05 +/- 0.01 and 0.008 +/- 0.002 mol/einstein, respectively. The results of this work and previous studies on the photochemistry of cis- and trans-Rh(en)/sub 2/(OH)X/sup n+/ (X = OH, H/sub 2/O) and cis- and trans-Rh(en)/sub 2/(H/sub 2/O)/sub 2//sup 3 +/ are consistent with a photochemistry mechanism involving excitation, ligand labilization, rearrangement of an excited-state, five-coordinate fragment, relaxation, and solvent addition. Ratios of the photochemical quantum yields for cis-L to cis-rac and cis to trans conversions agree with the conclusion that Rh(en)/sub 2/(OH)/sup 2 +/* is the species undergoing rearrangement in both the dihydroxo and aquo hydroxo systems. 24 references, 2 tables.

Basic Mechanisms in Photochemistry and Photobiology. Proceedings of an International Symposium Held at Caracas, Venezuela, December 4-8, 1967.J. W. Longworth

Previous articleNext article No AccessNew Biological BooksBasic Mechanisms in Photochemistry and Photobiology. Proceedings of an International Symposium Held at Caracas, Venezuela, December 4-8, 1967. J. W. Longworth Beatrice M. SweeneyBeatrice M. Sweeney Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The Quarterly Review of Biology Volume 45, Number 1Mar., 1970 Published in association with Stony Brook University Article DOIhttps://doi.org/10.1086/406483 Views: 1Total views on this site Copyright 1970 Stony Brook Foundation, Inc.PDF download Crossref reports no articles citing this article.

Mechanism of photochemistry of alkanones with .gamma.- hydrogens

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMechanism of photochemistry of alkanones with .gamma.- hydrogensNien-Chu Yang, Steven P. Elliott, and Bongsub KimCite this: J. Am. Chem. Soc. 1969, 91, 26, 7551–7553Publication Date (Print):December 1, 1969Publication History Published online1 May 2002Published inissue 1 December 1969https://doi.org/10.1021/ja01054a079RIGHTS & PERMISSIONSArticle Views97Altmetric-Citations42LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (390 KB) Get e-Alerts Get e-Alerts