Surface-catalyzed photochemical reactions of physisorbed molecules

Chen, C. J.; Osgood, R. M.

doi:10.1007/bf00614950

Cited by 34 publications

(15 citation statements)

References 23 publications

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“…The basis orbital energies of our two fragments N and A are defined as A A = (*AI~~I*A); AN (*~Iffl*p,) (1) The interaction between both fragments is described by a parameter @: P = (*NIHI*A) ( 2 ) (3)…”

Section: Discussionmentioning

confidence: 99%

“…2 The counter example with a perpendicularly twisted Technical University of Berlin. 1 University of Heidelberg. amino group is 5-cyanobenzoquinuclidine which shows only the TICT but not the short-wavelength B* band.…”

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confidence: 98%

“…5 In the latter one with the larger rotational volume the TICT formation is slowed down by a factor of nearly 2 which clearly shows that a rotational motion is separating B* and A* state, and that the measurement of fluorescence kinetics is a powerful tool for studying reaction mechanisms. The study of this very fast intramolecular rotation in the excited state-within some picoseconds in ordinary solvents at room temperat~re-~-~ can give valuable information on the structure of liquids, because two (1) Figure 1. Schematic potential energy diagram for the angular dependence of ground state and of B* and A* excited states in p-cyano-N,Ndialkylanilines for the case of a slight hindrance to planarity.…”

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confidence: 99%

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Dependence of intramolecular rotation in p-cyano-N,N-dialkylanilines on the twist angle. A fluorescence, UV absorption, and photoelectron spectroscopic study

Rettig¹,

Gleiter²

1985

J. Phys. Chem.

109

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study the adsorption of aliphatic nitriles at the Hg-aqueous solution interface. They proposed that succinonitrile adsorbed flat on the Hg surface with the two nitrile groups slightly turned toward the solution. Such a configuration necessitated the succinonitrile molecule to assume the thermodynamically unstable cis conformation or a conformation slightly different from cis.36 The present work on the Cu-aqueous solution interface indicates that succinonitrile adsorbs on the Cu surface in both the gauche and trans conformations, and that one of the CEN groups lies close to the metal surface and r-bonding results. Our findings are markedly different from Trasatti's; however, two different metal systems were involved.In conclusion, two isomeric species of succinonitrile, the gauche ARTICLES and trans, have been identified at the copper-succinonitrile solution interface. This is the first report of the observation of two rotational isomers on metal surfaces in surface-enhanced Raman spectroscopy.The rate constant for formation of the twisted intramolecular charge transfer (TICT) excited state of several dual fluorescing p-cyano-N,N-dialkylanilines is measured by using fluorescence decay kinetics and compared to the spectroscoeic ground-state twist angle (cp) derived from photoelectron (PE) spectroscopy. With increasing (cp), the rate constant k also increases considerably, in accordance with a scheme involving an excited-state crossing. PE and UV spectroscopy are used to show that the angular distribution function of flexible compounds is very broad as compared to that of compounds with a rigid carbon skeleton.

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Section: Discussionmentioning

confidence: 99%

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confidence: 98%

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confidence: 99%

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Dependence of intramolecular rotation in p-cyano-N,N-dialkylanilines on the twist angle. A fluorescence, UV absorption, and photoelectron spectroscopic study

Rettig¹,

Gleiter²

1985

J. Phys. Chem.

109

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“…Since energy transfer from solid to reactant is known to be possible, it is likely that energy deposited in the bulk solid by penetrating energy sources, such as mechanical stress or ionizing radiation, should be well moderated to less high-energy forms before transfer to a distant interfacially adsorbed reactant. It is also the case that excess energy in the absorbed reactant can be transferred to the absorbing solid (Chen and Osgood, 1983). Thus, energy fields that in the gas phase would be as destructive as they are productive may be considerably more productive when applied to a solid-state mediator.…”

Section: Iia Surface Manifestationsmentioning

confidence: 97%

A possible energetic role of mineral surfaces in chemical evolution

Coyne

1985

Origins Life Evol Biosphere

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The postulated roles of clays and other minerals in chemical evolution and the origin of life are reconsidered in terms of the interaction of these minerals with penetrating sources of energy such as ionizing radiation and mechanical stress. This interaction, including such facets as excitation, degradation, storage, and transfer, is considered here with regard to its profound potential for altering the capabilities of minerals to serve both as substrates for prebiological chemistry and as inorganic prototypic life forms. The interaction of minerals and energy in relationship to surface chemistry is discussed in terms of the spectroscopic properties of minerals, the interaction of energy with condensed phases, some commonly accepted concepts of heterogeneous catalysis in the absence of electronic energy inputs, and some commonly accepted and novel means by which surface activity might be enhanced in the presence of energy inputs. An estimation is made of the potential contribution of two poorly characterized prebiotic energy sources, natural radioactive decay and triboelectric energy. These estimates place a conservative lower limit on their prebiotic abundance. Also some special properties of these energy sources, relative to solar energy, are pointed out which might give them particular suitability for driving reactions occurring under geological conditions. Skeletal support for this broadly defined framework of demonstrated and potential relationships between minerals, electronic excitation, and surface reactivity, as applied to chemical evolution, is provided from the results of our studies on 1/1 clays. We have discovered and partially characterized a number of novel luminescent properties of these clays, that indicate energy storage and transfer processes in clays. These luminescent properties are interpreted in relationship to the electron spin resonance phenomena, to provide a basis for estimating the potential significance of energy storage and transduction in monitoring or driving clay surface chemistry. Consideration of the electronic structure of abundant minerals in terms of band theory and localized defect centers provides a predictive theoretical framework from which to rationalize the capacity of these materials to store and transduce energy. The bulk crystal is seen as a collecting antenna for electronic energy, with the defect centers serving as storage sites. The clay properties produced by isomorphic substitution appear to be intimately associated with all of the life-mimetic chemical processes that have been attributed to clays.(ABSTRACT TRUNCATED AT 400 WORDS)

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“…However, the study of the electronically excited states of adsorbed molecules is important in fields such as photochemistry and photoluminescence at surfaces. [2][3][4] Furthermore, the study of excited states yields information about the changes in electronic structure that occur on adsorption, and this can provide additional insight into the adsorption process.…”

Section: Introductionmentioning

confidence: 99%

Theoretical study of the electronic spectroscopy of CO adsorbed on Pt(111)

Besley

2005

The Journal of Chemical Physics

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The excited states of CO adsorbed on the Pt(111) surface are studied using a time-dependent density functional theory formalism. To reduce the computational cost, electronic excitations are computed within a reduced single excitation space. Using cluster models of the surface, excitation energies are computed for CO in the on-top, threefold, and bridge binding sites. On adsorption, there is a lowering of the 5sigma orbital energy. This leads to a large blueshift in the 5sigma- -> pi(CO*) excitation energy for all adsorption sites. The 1pi and 4sigma orbital energies are lowered to a lesser extent, and smaller shifts in the corresponding excitation energies are predicted. For the larger clusters, pi* excitations at lower energies are observed. These transitions correspond to excitations to virtual orbitals of pi* character which lie below the pi* orbitals of gas phase CO. These orbitals are associated predominantly with the metal atoms of the cluster. The excitation energies are also found to be sensitive to changes in the adsorption geometry. The electronic spectrum of CO on Pt(111) is simulated and the assignment of the bands observed in experimental electron energy loss spectroscopy discussed.

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Surface-catalyzed photochemical reactions of physisorbed molecules

Cited by 34 publications

References 23 publications

Dependence of intramolecular rotation in p-cyano-N,N-dialkylanilines on the twist angle. A fluorescence, UV absorption, and photoelectron spectroscopic study

Dependence of intramolecular rotation in p-cyano-N,N-dialkylanilines on the twist angle. A fluorescence, UV absorption, and photoelectron spectroscopic study

A possible energetic role of mineral surfaces in chemical evolution

Theoretical study of the electronic spectroscopy of CO adsorbed on Pt(111)

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