Cosmic-ray-driven electron-induced reactions of halogenated molecules adsorbed on ice surfaces: Implications for atmospheric ozone depletion and global climate change

Lu, Qing‐Bin

doi:10.1016/j.physrep.2009.12.002

Cited by 61 publications

(112 citation statements)

References 135 publications

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“…29 In part, this has been circumvented by decoupling by rare gas buffer layers. 3 The recent discovery of much longer living electrons at the vacuum interface of supported ice crystallites with excited state lifetimes up to minutes 41,42 now crosses the bridge between the surface science approach and the gas phase cluster anion studies: The excess electrons are created by charge transfer from the metal substrate as in previous surface science studies; however, they are trapped at preexisting sites at the surface of the ice crystallites. In these deep traps, the electrons are strongly screened and very efficiently decoupled electronically from the metal.…”

Section: Intoductionmentioning

confidence: 99%

Dynamics and Reactivity of Trapped Electrons on Supported Ice Crystallites

2011

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The solvation dynamics and reactivity of localized excess electrons in aqueous environments have attracted great attention in many areas of physics, chemistry, and biology. This manifold attraction results from the importance of water as a solvent in nature as well as from the key role of low-energy electrons in many chemical reactions. One prominent example is the electron-induced dissociation of chlorofluorocarbons (CFCs). Low-energy electrons are also critical in the radiation chemistry that occurs in nuclear reactors. Excess electrons in an aqueous environment are localized and stabilized by the local rearrangement of the surrounding water dipoles. Such solvated or hydrated electrons are known to play an important role in systems such as biochemical reactions and atmospheric chemistry. Despite numerous studies over many years, little is known about the microscopic details of these electron-induced chemical processes, and interest in the fundamental processes involved in the reactivity of trapped electrons continues. In this Account, we present a surface science study of the dynamics and reactivity of such localized low-energy electrons at D(2)O crystallites that are supported by a Ru(001) single crystal metal surface. This approach enables us to investigate the generation and relaxation dynamics as well as dissociative electron attachment (DEA) reaction of excess electrons under well-defined conditions. They are generated by photoexcitation in the metal template and transferred to trapping sites at the vacuum interface of crystalline D(2)O islands. In these traps, the electrons are effectively decoupled from the electronic states of the metal template, leading to extraordinarily long excited state lifetimes on the order of minutes. Using these long-lived, low-energy electrons, we study the DEA to CFCl(3) that is coadsorbed at very low concentrations (∼10(12) cm(-2)). Using rate equations and direct measurement of the change of surface dipole moment, we estimated the electron surface density for DEA, yielding cross sections that are orders of magnitude higher than the electron density measured in the gas phase.

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Section: Intoductionmentioning

confidence: 99%

Dynamics and Reactivity of Trapped Electrons on Supported Ice Crystallites

2011

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“…biophysics | physical biology | chemical biology | biological chemistry E lectron-transfer reactions play key roles in diverse processes in chemistry, physics, and biology, ranging from photo-induced reactions (1,2), electron tunneling in proteins (3), and electron transport in DNA (4) to the ozone hole formation (5) and reductive DNA damage (6,7). Electron-transfer reactions in molecular systems have therefore been the subject of intense experimental and theoretical studies.…”

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confidence: 99%

Electron transfer-based combination therapy of cisplatin with tetramethyl- p -phenylenediamine for ovarian, cervical, and lung cancers

Luo

Nguyen

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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The platinum-based chemotherapy is the standard treatment for several types of cancer. However, cancer cells often become refractory with time and most patients with serious cancers die of drug resistance. Recently, we have discovered a unique dissociative electron-transfer mechanism of action of cisplatin, the first and most widely used platinum-based anticancer drug. Here, we show that the combination of cisplatin with an exemplary biological electron donor, N,N,N′,N′-tetramethyl-p-phenylenediamine (TMPD), may overcome the resistance of cancer cells to cisplatin. Our steady-state absorption and fluorescence spectroscopic measurements confirm the effective dissociative electron-transfer reaction between TMPD and cisplatin. More significantly, we found that the combination of 100 μM TMPD with cisplatin enhances double-strand breaks of plasmid DNA by a factor of approximately 3.5 and dramatically reduces the viability of cisplatin-sensitive human cervical (HeLa) cancer cells and highly cisplatin-resistant human ovarian (NIH:OVCAR-3) and lung (A549) cancer cells. Furthermore, this combination enhances apoptosis and DNA fragmentation by factors of 2-5 compared with cisplatin alone. These results demonstrate that this combination treatment not only results in a strong synergetic effect, but also makes resistant cancer cells sensitive to cisplatin. Because cisplatin is the cornerstone agent for the treatment of a variety of human cancers (including testicular, ovarian, cervical, bladder, head/neck, and lung cancers), our results show both the potential to improve platinum-based chemotherapy of various human cancers and the promise of femtomedicine as an emerging frontier in advancing cancer therapy.biophysics | physical biology | chemical biology | biological chemistry E lectron-transfer reactions play key roles in diverse processes in chemistry, physics, and biology, ranging from photo-induced reactions (1, 2), electron tunneling in proteins (3), and electron transport in DNA (4) to the ozone hole formation (5) and reductive DNA damage (6, 7). Electron-transfer reactions in molecular systems have therefore been the subject of intense experimental and theoretical studies. Following the pioneering contribution of Zewail (8), the advent of femtosecond time-resolved laser spectroscopy (fs-TRLS; 1 fs ¼ 10 −15 s) provided an unprecedented capacity in techniques of observing molecular reactions, including electron transfer. Its application to the study of chemical and biological systems led to the birth of new scientific subfields: femtochemistry and femtobiology (8). Recently, Lu (9) further proposed that integrating ultrafast laser techniques with biomedical methods to advance fundamental understandings and treatments of major human diseases might lead to the opening of a new frontier called femtomedicine. Regarding the latter, we have recently unraveled unique dissociative electron-transfer (DET) mechanisms of reductive DNA damage (6, 7) and several anticancer agents for radiotherapy and chemotherapy (10)(11)(12)(13)(14...

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“…Perhaps the most pronounced example is the stratospheric ozone depletion process, where the ice particles in polar stratospheric clouds (PSC) play a key role (Peter, 1997; Solomon, 1999; Prenni and Tolbert, 2001; Lu, 2010). The investigations of small nanometer-size particles directly in the atmosphere are difficult thus such studies are yet scarce, and large ambiguities exist in this size region.…”

Section: Introductionmentioning

confidence: 99%

Atmospheric processes on ice nanoparticles in molecular beams

Fárnı́k

Poterya

2014

Front. Chem.

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This review summarizes some recent experiments with ice nanoparticles (large water clusters) in molecular beams and outlines their atmospheric relevance: (1) Investigation of mixed water–nitric acid particles by means of the electron ionization and sodium doping combined with photoionization revealed the prominent role of HNO3 molecule as the condensation nuclei. (2) The uptake of atmospheric molecules by water ice nanoparticles has been studied, and the pickup cross sections for some molecules exceed significantly the geometrical sizes of the ice nanoparticles. (3) Photodissociation of hydrogen halides on water ice particles has been shown to proceed via excitation of acidically dissociated ion pair and subsequent biradical generation and H3O dissociation. The photodissociation of CF2Cl2 molecules in clusters is also mentioned. Possible atmospheric consequences of all these results are briefly discussed.

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Cosmic-ray-driven electron-induced reactions of halogenated molecules adsorbed on ice surfaces: Implications for atmospheric ozone depletion and global climate change

Cited by 61 publications

References 135 publications

Dynamics and Reactivity of Trapped Electrons on Supported Ice Crystallites

Dynamics and Reactivity of Trapped Electrons on Supported Ice Crystallites

Electron transfer-based combination therapy of cisplatin with tetramethyl- p -phenylenediamine for ovarian, cervical, and lung cancers

Atmospheric processes on ice nanoparticles in molecular beams

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