Download or read book Femtosecond Time resolved Pump probe Spectroscopy on Electron Transfer in Mono and Polynucleotides and in DNA written by Mark A. Day and published by . This book was released on 2004 with total page 446 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Femto to Nanosecond Time Resolved Pump Probe Spectroscopy on Electron Transfer in Ferrocenophanone Oxazine 1 Merocyanine 3 TiO2 and Acridine Modified DNA written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Special Issues of the ultrafast electron transfer dynamics in the following donor/acceptor-systems were investigated: (1) Ferrocenophanone/Oxazine-1 in methylene-chloride. It was shown that the time constants of the fs-time-resolved IR-absorption spectra were identical to the UV/VIS spectra. An alternative method to monitor the charge transfer processes was established which is suitable for the investigation of donor/acceptor-systems containing small molecules whose absorption in the UV is superimposed by other optical transitions. (2) Merocyanine-3/TiO2 in aqueous solution. The strongly dispersive recombination dyanmics in the ns-ms time window was studied and theoretical models for explanation were discussed. (3) Short acridine-modified DNA-double-strands in aqueous solution. The activation energy of the time-resolved oxidation-dyanmics of guanine was determined for the first time by temperature dependent measurements as a function of duplex sequence.
Download or read book Femto to Nanosecond Time Resolved Pump Probe Spectroscopy on Electron Transfer in Ferrocenophanone oxazine 1 Merocyanine 3 TiO 2 and Acridine modified DNA written by Reinhard Haselsberger and published by . This book was released on 2003 with total page 137 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Femtosecond UV and Infrared Time resolved Spectroscopy of DNA written by Kimberly Desneiges De La Harpe and published by . This book was released on 2011 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: DNA contains the genetic code for all life. The nucleic acid bases that comprise DNA readily absorb ultraviolet light, making them susceptible to photodamage that can lead to mutations and skin cancer. Knowledge of the pathways by which excess electronic energy is dissipated in DNA is important for understanding how photodamage to DNA occurs. The aim of this work is to understand the effect of sequence and secondary structure on the excited-state dynamics in a diverse set of DNA systems. The excited-state dynamics of various GC-containing oligonucleotides were studied by femtosecond transient absorption spectroscopy. Long-lived states with lifetimes at least an order of magnitude slower than the constituent monomers were observed in all the systems studied. Significantly altering the structural conformation of d(GC)9 d(GC)9 through the use of high ionic conditions and low pH revealed that long-lived excited state lifetimes were nearly independent of base stacking geometries and base pairing motifs. The electronic coupling for charge recombination in the long-lived exciplex states of d(GC)9 d(GC)9 is proposed to be large and not significantly altered by helix conformation. The driving force, rather than electronic coupling, for charge recombination is proposed to influence strongly the decay of the long-lived exciplex states in this duplex. Transient absorption experiments were carried out on a genomic DNA sequence to study the effect of sequence disorder on excite-state dynamics. Long-lived excited states were observed in the individual single strands as well as in the duplex of the ras61 oligodeoxynucleotide. The lifetimes of the individual strands were sensitive to composition, with a slower decay observed for the purine-rich strand compared to the pyrimidine-rich strand. In addition, a large ultrafast decay component was observed in the duplex suggesting monomer-like decay pathways are accessible in well-stacked DNA systems. This study shows that long-lived excited states are not an artifact of well-ordered model systems, but are also present in genomic DNA. Isotopic studies revealed a pronounced deuterium isotope effect on the excited-state dynamics of alternating GC-containing oligonucleotides that is not present in non-alternating GC-duplexes. This result parallels those of similar AT-DNAs and is proposed to involve interstrand proton transfer initiated by the formation of an exciplex state with significant charge transfer character. To investigate further the possibility of interstrand proton transfer in DNA duplexes, a series of A- and T-containing oligonucleotides were studied by UV-pump / mid-IR probe spectroscopy. Unique, strong positive bands are observed in alternating AT-DNA, but not in the single- and double-strand non-alternating AT-oligomers. These bands are proposed to be marker bands for proton transfer. Possible absorption bands for excimer states were also observed in (dA)1 in the spectral region of 1500 - 1800 cm−1, supporting previous measurements on polyA.
Download or read book Femtosecond Spectroscopy of Electron Transfer in DNA and Azsomethine Ylides written by Douglas James Whittaker and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Proceedings of the National Academy of Sciences of the United States of America written by National Academy of Sciences (U.S.) and published by . This book was released on 1999 with total page 1472 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Femtosecond Time resolved Spectroscopy in Studying Excited state Electron and Proton Transfer Reactions written by 謝承志 and published by . This book was released on 2010 with total page 209 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Index to Theses with Abstracts Accepted for Higher Degrees by the Universities of Great Britain and Ireland and the Council for National Academic Awards written by and published by . This book was released on 2006 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt: Theses on any subject submitted by the academic libraries in the UK and Ireland.
Download or read book Femtosecond Photoelectron Spectroscopy written by Benjamin Jefferys Greenblatt and published by . This book was released on 1999 with total page 554 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Femtosecond Time resolved Spectroscopy of Gas phase Anions written by I-Ren Lee and published by . This book was released on 2011 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents the studies of ultrafast dynamics of negatively charged molecules and clusters in the gas phase using femtosecond photoelectron spectroscopy. The core motifs of two distinct complex systems - solvated electrons and protein chromophores - were studied in the gas phase. For the solvated electron systems - hydrated electrons and ammoniated electrons - were studied in finite-sized clusters in the gas phase. Interestingly, the results show a significant difference. In the hydrated electron, ground-state vibrational cooling is evident by the transient photoelectron spectra, while, in the ammoniated electron, a coherent motion with a 500-fs relaxation is observed. The difference is attributed to the cage rigidity, which results in different solvent motions for the electron's interaction with water (libration) or ammonia (phonon-like). The photocycle of the photoactive yellow protein (PYP) has been studied extensively, but the dynamics of the isolated chromophore responsible for the transduction of phototacticity is less known. The anionic chromophore model molecule was investigated in the gas phase using femtosecond photoelectron spectroscopy and the results indicate that the protein function is in directing efficient conversion to the cis-structure and in impeding radical formation within the protein. Finally, a classic system of conformational twisting, stilbene, was studied in its anionic radical state. Ultrafast conversions from both trans- and cis- isomers are accompanied with coherent oscillation, in contrast to observations in the solution phase, and this suggests that a major solvent retardation take place. Dynamic studies of the photochemistry of gas-phase anions are very scarce due to the experimental difficulties. However, our results successfully resolve the photophysics and photochemistry of the isolated species and, thereby, elucidate the effect of solution.
Download or read book Monitoring Electron Transfer Reactions Using Ultrafast UV visible and Infrared Spectroscopy written by Lynetta M. Mier and published by . This book was released on 2012 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: The electron transfer processes in organic molecules were examined using ultrafast time resolved spectroscopies. The two-photon ionization of trans-stilbene was analyzed using femtosecond, excited state, electronic and vibrational spectroscopies. It was found that the ionization process occurs instantaneously, but the charge separation and the charge recombination are competing pathways. The charge separation was found to occur within 20 ps while the charge recombination occurs in 50 ps. To further characterize these processes in trans-stilbene and to measure the electron transfer processes between poly(3-hexylthiophene) (P3HT) and N, N'-dioctyl-3,4,9,10-perylenedicarboximide (PDI-C8) the technique of femtosecond stimulated Raman spectroscopy (FSRS) was developed in order to measure the excited state Raman spectrum. It was found that the excited state Raman spectrum contains many features from states and processes not associated with the excited state. Due to the complications with the measurement of the FSRS spectrum for molecules, the electron transfer dynamics between P3HT and PDI-C8 were measured using femtosecond, excited state, visible and infrared spectroscopies. It was found that no electron transfer occurs from the excited state of PDI-C8 to the P3HT. It was also found that from the excited state of P3HT and electron is transferred to PDI-C8 within the time resolution of the laser (
Download or read book Synthesis of Novel Photophysical Probes in Ultrafast DNA Dynamics Study written by Hai Liu and published by . This book was released on 2006 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: DNA functions and malfunctions through a variety of chemical reactions. To study ultrafast dynamics of DNA could help us to understand the environment DNA provides for its reactions; electron transfer and charge transfer involved chemical reaction; Physical properties of DNA and et al. TRSS, Time-Resolved Stokes Shift Spectroscopy, is the best established and most robust spectroscopic method to study electronic-state salvation dynamics. In our study, TRSS can be applied to study ultrafast dynamics of DNA by placing a fluorophore inside DNA, which is considered as its "solvent". Two new fluorescent probes have been designed, synthesized and characterized to be applied in TRSS experiments. Based on previous work developed in the Coleman group, coumarin phosphoramidite and anthracene phosphoramidite were synthesized via palladium catalyzed Heck reaction and were ready for solid-phase DNA synthesis.
Download or read book Femtosecond time resolved photoelectron spectroscopy in the extreme ultraviolet region written by Peter Šiffalovič and published by . This book was released on 2002 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Time Resolved Photoelectron Spectroscopy of DNA Molecules in Solution written by and published by . This book was released on 2015 with total page 125 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Femtosecond Pump probe Spectroscopy of Chemical Reactions in Liquids and Crystals written by Dutch D. Chung and published by . This book was released on 1998 with total page 205 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Femtosecond Time resolved Photoelectron Spectroscopy of Phenol written by Carolyn Patricia Schick and published by . This book was released on 2000 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Towards Femtosecond Time Resolved Electron Spectroscopy for Chemical Analysis written by Annette Pietzsch and published by . This book was released on 2008 with total page 89 pages. Available in PDF, EPUB and Kindle. Book excerpt:
