The solid state photo-CIDNP effect

Photochemically induced dynamic nuclear polarization (photo-CIDNP) is non-Boltzmann nuclear magnetization which can be observed by magic angle spinning NMR spectroscopy as enhanced absorptive or emissive signals. In solids, photo-CIDNP has been observed since its discovery in 1994 in various photosynthetic reaction centers. In natural photosynthetic charge separation, electron-electron interactions are fine-tuned to lead to highly efficient electron transfer. Nanosecond laser-flash photo-CIDNP magic-angle spinning NMR allows for determination of the nuclear polarizations and hyperfine interactions with atomic selectivity and with a resolution of a few microseconds. The build-up of nuclear polarization in reaction centers of Rhodobacter sphaeroides is found to depend on the presence and lifetimes of the molecular triplet states of the donor and carotenoid. Time-resolved 13C photo-CIDNP MAS NMR spectroscopy is used to map the electronic structure of the donor. In the dark state, maximum electron density is localized in the center of the special pair. In contrast, in the light state, the maximum of the electron spin density is localized at the periphery of the two cofactors. The balance of electron spin density between the two bacteriochlorophyll cofactors is shifted in favor of the L branch of the protein by the ratio of 7:3. We show that the asymmetry is induced by both geometric differences between the two cofactors and non-covalent interactions with the protein.EMBO, NWO, Spectraphysics-Newport, Bruker BiospinUBL - phd migration 201

Action Spectroscopy on Dense Samples of Photosynthetic Reaction Centers of Rhodobacter sphaeroides WT Based on Nanosecond Laser-Flash 13C Photo-CIDNP MAS NMR

Photochemically induced dynamic nuclear polarization magic-angle spinning nuclear magnetic resonance (photo-CIDNP MAS NMR) allows for the investigation of the electronic structure of the photochemical machinery of photosynthetic reaction centers (RCs) at atomic resolution. For such experiments, either continuous radiation from white xenon lamps or green laser pulses are applied to optically dense samples. In order to explore their optical properties, optically thick samples of isolated and quinone-removed RCs of the purple bacteria of Rhodobacter sphaeroides wild type are studied by nanosecond laser-flash 13C photo-CIDNP MAS NMR using excitation wavelengths between 720 and 940 nm. Action spectra of both the transient nuclear polarization as well as the nuclear hyperpolarization, remaining in the electronic ground state at the end of the photocycle, are obtained. It is shown that the signal intensity is limited by the amount of accessible RCs and that the different mechanisms of the photo-CIDNP production rely on the same photophysical origin, which is the photocycle induced by one single photon

Nanosecond-Flash N-15 Photo-CIDNP MAS NMR on reaction centers of Rhodobacter sphaeroides R26

Solid state NMR/Biophysical Organic ChemistryBiological and Soft Matter Physic

Historical Overview of the Human Population-Genetic Studies in Bosnia and Herzegovina: Small Country, Great Diversity

Modern Bosnia and Herzegovina is a multinational and multi-religious country, situated in the western part of the Balkan Peninsula in South-eastern Europe. According to recent archaeological findings, Bosnia and Herzegovina has been occupied by modern humans since the Palaeolithic period. The structure of Bosnia-Herzegovina’s human populations is very complex and specific, due to which it is interesting for various population-genetic surveys. The population of Bosnia and Herzegovina has been the focus of bio-anthropological and population genetics studies since the 19th century. The first known bio-anthropological analyses of Bosnia-Herzegovina population were primarily based on the observation of some phenotypic traits. Later examinations included cytogenetic and DNA based molecular markers. The results of all studies which have been done up to date showed no accented genetic difference among the populations (based on geographical regions) with quite high diversity within them. Human population of Bosnia and Herzegovina is closely related to other populations in the Balkans. However, there are still many interesting features hidden within the existing diversity of local human populations that are still waiting to be discovered and described

Spectral editing through laser-flash excitation in two-dimensional photo-CIDNP MAS NMR experiments

Solid state NMR/Biophysical Organic Chemistr

Observation of the solid-state photo-CIDNP effect in entire cells of cyanobacteria Synechocystis

Cyanobacteria are widely used as model organism of oxygenic photosynthesis due to being the simplest photosynthetic organisms containing both photosystem I and II (PSI and PSII). Photochemically induced dynamic nuclear polarization (photo-CIDNP) 13C magic-angle spinning (MAS) NMR is a powerful tool in understanding the photosynthesis machinery down to atomic level. Combined with selective isotope enrichment this technique has now opened the door to study primary charge separation in whole living cells. Here, we present the first photo-CIDNP observed in whole cells of the cyanobacterium Synechocystis

The Grizzly, October 15, 1982

Students for Peace and Progress Get Started • Homecoming 1982 • Annual Parents Day a Success • Letters to the Editor • Opinion: Sorority Rushing Needs Revision • Lantern Format Undecided • Dance-a-Thon for Lupus • Japan: Big and Real • New Art at Myrin • Bear Booters Win Three • Now Hold it Just a Minute! • Grizzlies Win Third Straight • X-Country Wins • Penn Blasts Lady Bears 3-0https://digitalcommons.ursinus.edu/grizzlynews/1084/thumbnail.jp

The Grizzly, December 3, 1982

Graterford Prisoners Counseled • Phi Psi Sponsors Santa • Chem Society Rated Outstanding • Renowned Professor Dies • Steinbright Scholarships Offered • News Briefs: Sigma Pi Sigma Inducts New Members; Operation Native Talent; New Evening School Class; Winterfest II Schedules Events; Going for Baroque • Commuters Don\u27t Get No Respect! • Letters to the Editor • Is Tuition Increase Justified? • Recent Thefts and Attacks Prompt Security Questions • Cheating at Ursinus? • A Last Squeeze Before Departing • The Missionary: A Blessing • Roving Reporter: How Do You Feel About the New Security System in the Quad? • Challenge Yourself at Outward Bound • The Perfect Man • UC Faculty Not Burnt Out • Sports Profile: Mullahy and Bazow, Football Captains • Women\u27s Basketball Tops Aggies in Opener: Jankauskas Scoring and Rebounding Was Key • UC Making a Contribution to Olympic Efforthttps://digitalcommons.ursinus.edu/grizzlynews/1090/thumbnail.jp

The solid-state photo-CIDNP effect

The solid-state photo-CIDNP effect is the occurrence of a non-Boltzmann nuclear spin polarization in rigid samples upon illumination. For solid-state NMR, which can detect this enhanced nuclear polarization as a strong modification of signal intensity, the effect allows for new classes of experiments. Currently, the photo- and spin-chemical machinery of various RCs is studied by photo-CIDNP MAS NMR in detail. Until now, the effect has only been observed at high magnetic fields with 13C and 15N MAS NMR and in natural photosynthetic RC preparations in which blocking of the acceptor leads to cyclic electron transfer. In terms of irreversible thermodynamics, the high-order spin structure of the initial radical pair can be considered as a transient order phenomenon emerging under non-equilibrium conditions and as a first manifestation of order in the photosynthetic process. The solid-state photo-CIDNP effect appears to be an intrinsic property of natural RCs. The conditions of its occurrence seem to be conserved in evolution. The effect may be based on the same fundamental principles as the highly optimized electron transfer. Hence, the effect may allow for guiding artificial photosynthesis

The Grizzly, February 11, 1983

Bookstore Explains Pricing Policy • Scottish Scholarships Offered to Sophomores • Weekend Alcohol Policy: Campus is Dry • Ursinus Gets Bucks From Sears Roebuck • President\u27s Corner • Visser Fills Exhibits in Corson • Letters to the Editor: Professor Laments Social Conditions at UC; I.F.C. President Irate; President\u27s Response; Bitter About Policy • Varying Viewpoints • Stravinsky to End Winterfest • U.C. Flu Flattens Students • Reaganomics Forum • Key Shooting Aids Lady Hoopsters\u27 Record • Basketball Laments Second Half Loss • Swimmers Glide to Third Straight Victory • Grapplers Deemed Tough • Basketball: End of an Era?? • Swimmers Stroke for Two Wins • Gymnasts Win by 0.75https://digitalcommons.ursinus.edu/grizzlynews/1093/thumbnail.jp