Lin, Milo M., Meinhold, Lars, Shorokhov, Dmitry, Zewail, Ahmed H.
A 2D free-energy landscape model is presented to describe the (un)folding transition of DNA/RNA hairpins, together with molecular dynamics simulations and experimental findings. The dependence of the...
4D visualization of embryonic, structural crystallization by single-pulse microscopy (2008)
Kwon, Oh-Hoon, Barwick, Brett, Park, Hyun Soon, Baskin, J. Spencer, Zewail, Ahmed H.
4D electron imaging: principles and perspectives (2008)
Shorokhov, Dmitry, Zewail, Ahmed H.
In this perspective we highlight developments and concepts in the field of 4D electron imaging. With spatial and temporal resolutions reaching the picometer and femtosecond, respectively, the field...
Gahlmann, Andreas, Park, Sang Tae, Zewail, Ahmed H.
Pulsed electron beams allow for the direct atomic-scale observation of structures with femtosecond to picosecond temporal resolution in a variety of fields ranging from materials science to chemistry...
Structural Preablation Dynamics of Graphite Observed by Ultrafast Electron Crystallography (2008)
Carbone, Fabrizio, Baum, Peter, Rudolf, Petra, Zewail, Ahmed H.
By means of time-resolved electron crystallography, we report direct observation of the structural dynamics of graphite, providing new insights into the processes involving coherent lattice motions...
Structural Preablation Dynamics of Graphite Observed by Ultrafast Electron Crystallography (2008)
Carbone, Fabrizio, Baum, Peter, Rudolf, Petra, Zewail, Ahmed H.
By means of time-resolved electron crystallography, we report direct observation of the structural dynamics of graphite, providing new insights into the processes involving coherent lattice motions...
Attosecond electron pulses for 4D diffraction and microscopy (2007)
In this contribution, we consider the advancement of ultrafast electron diffraction and microscopy to cover the attosecond time domain. The concept is centered on the compression of femtosecond...
Meinhold, Lars, Smith, Jeremy C., Kitao, Akio, Zewail, Ahmed H.
Microscopic statistical pressure fluctuations can, in principle, lead to corresponding fluctuations in the shape of a protein energy landscape. To examine this, nanosecond molecular dynamics...
Ultrafast light-induced response of photoactive yellow protein chromophore analogues (2007)
Espagne, Agathe, Paik, Daniel H., Changenet-Barret, Pascale, Plaza, Pascal, Martin, Monique M., Zewail, Ahmed H.
The fluorescence decays of several analogues of the photoactive yellow protein (PYP) chromophore in aqueous solution have been measured by femtosecond fluorescence up-conversion and the corresponding...
Double proton transfer dynamics of model DNA base pairs in the condensed phase (2007)
Kwon, Oh-Hoon, Zewail, Ahmed H.
The dynamics of excited-state double proton transfer of model DNA base pairs, 7-azaindole dimers, is reported using femtosecond fluorescence spectroscopy. To elucidate the nature of the transfer in...
DNA folding and melting observed in real time redefine the energy landscape (2007)
Ma, Hairong, Wan, Chaozhi, Wu, Aiguo, Zewail, Ahmed H.
We report real-time observations of the folding and melting of DNA by probing two active sites of a hairpin structure, the bases and the stem end, and using an ultrafast T-jump. Studies at different...
Four-dimensional ultrafast electron microscopy of phase transitions (2006)
Grinolds, Michael S., Lobastov, Vladimir A., Weissenrieder, Jonas, Zewail, Ahmed H.
Reported here is direct imaging (and diffraction) by using 4D ultrafast electron microscopy (UEM) with combined spatial and temporal resolutions. In the first phase of UEM, it was possible to obtain...
Breaking resolution limits in ultrafast electron diffraction and microscopy (2006)
Ultrafast electron microscopy and diffraction are powerful techniques for the study of the time-resolved structures of molecules, materials, and biological systems. Central to these approaches is the...
Ultrafast vectorial and scalar dynamics of ionic clusters: Azobenzene solvated by oxygen (2006)
Paik, D. Hem, Baskin, J. Spencer, Kim, Nam Joon, Zewail, Ahmed H.
The ultrafast dynamics of clusters of trans-azobenzene anion (A–) solvated by oxygen molecules was investigated using femtosecond time-resolved photoelectron spectroscopy. The time scale for...
Protein surface hydration mapped by site-specific mutations (2006)
Qiu, Weihong, Kao, Ya-Ting, Zhang, Luyuan, Yang, Yi, Wang, Lijuan, Stites, Wesley E., ...
Water motion at protein surfaces is fundamental to protein structure, stability, dynamics, and function. By using intrinsic tryptophans as local optical probes, and with femtosecond resolution, it is...
Dynamics of clusters: From elementary to biological structures (2006)
Cheng, Po-Yuan, Baskin, J. Spencer, Zewail, Ahmed H.
Between isolated atoms or molecules and bulk materials there lies a class of unique structures, known as clusters, that consist of a few to hundreds of atoms or molecules. Within this range of...
Park, Sang Tae, Feenstra, Jonathan S., Zewail, Ahmed H.
The photophysics and photochemistry of molecules with complex electronic structures, such as aromatic carbonyls, involve dark structures of radiationless processes. With ultrafast electron...
4D ultrafast electron diffraction, crystallography, and microscopy (2006)
In this review, we highlight the progress made in the development of 4D ultrafast electron diffraction (UED), crystallography (UEC), and microscopy (UEM) with a focus on concepts, methodologies, and...
Lee, I-Ren, Lee, Wonchul, Zewail, Ahmed H.
The cycle of the photoactive yellow protein (PYP) has been extensively studied, but the dynamics of the isolated chromophore responsible for transduction is unknown. Here, we present real-time...
Ultrafast Chemical Dynamics of Reactions in Beams (2006)
The research in this proposal focused on the development of femtosecond laser techniques and their applications in the studies of molecular dynamics in real time. The research resulted in some...
Qiu, Weihong, Zhang, Luyuan, Okobiah, Oghaghare, Yang, Yi, Wang, Lijuan, Zhong, Dongping, ...
Author Institution: Departments of Physics, Chemistry, and Biochemistry, Programs of Biophysics, Chemical Physics, and Biochemistry, The Ohio State University, Columbus, OH 43210; Laboratory of...
Feenstra, Jonathan S., Park, Sang Tae, Zewail, Ahmed H.
In this communication, we report on the use of ultrafast electron diffraction to determine structural dynamics of excited states and reaction products of isolated aromatic carbonyls, acetophenone and...
Xia, Tianbing, Wan, Chaozhi, Roberts, Richard W., Zewail, Ahmed H.
The transcription antiterminator IN protein from bacteriophage x uses its arginine-rich motif to specifically bind a stem-loop RNA hairpin (boxB) as a bent alpha-helix. A single stacking interaction...
Chen, Songye, Seidel, Marco T., Zewail, Ahmed H.
The structure and dynamics of a biological model bilayer are reported with atomic-scale resolution by using ultrafast electron crystallography. The bilayer was deposited as a Langmuir-Blodgett...
Four-dimensional ultrafast electron microscopy (2005)
Lobastov, Vladimir A., Srinivasan, Ramesh, Zewail, Ahmed H.
Electron microscopy is arguably the most powerful tool for spatial imaging of structures. As such, 2D and 3D microscopies provide static structures with subnanometer and increasingly with...
Human myoglobin recognition of oxygen: Dynamics of the energy landscape (2004)
Wang, Yuhong, Baskin, J. Spencer, Xia, Tianbing, Zewail, Ahmed H.
Femtosecond to nanosecond dynamics of O2 rebinding to human WT myoglobin and its mutants, V68F and I107F, have been studied by using transient absorption. The results are compared with NO rebinding....
Ultrafast hydration dynamics in protein unfolding: Human serum albumin (2004)
Kamal, J. K. Amisha, Zhao, Liang, Zewail, Ahmed H.
We report studies of unfolding and ultrafast hydration dynamics of the protein human serum albumin. Unique in this study is our ability to examine different domains of the same protein and the...
Ruan, Chong-Yu, Vigliotti, Franco, Lobastov, Vladimir A., Chen, Songye, Zewail, Ahmed H.
The static structure of macromolecular assemblies can be mapped out with atomic-scale resolution by using electron diffraction and microscopy of crystals. For transient nonequilibrium structures,...
Site- and sequence-selective ultrafast hydration of DNA (2003)
Pal, Samir Kumar, Zhao, Liang, Xia, Tianbing, Zewail, Ahmed H.
Water molecules in the DNA grooves are critical for maintaining structural integrity, conformational changes, and molecular recognition. Here we report studies of site- and sequence-specific...
Xia, Tianbing, Becker, Hans-Christian, Wan, Chaozhi, Frankel, Adam, Roberts, Richard W., Zewail, Ahmed H.
The N protein from bacteriophage {lambda} is a key regulator of transcription antitermination. It specifically recognizes a nascent mRNA stem loop termed boxB, enabling RNA polymerase to read through...
Water at DNA surfaces: Ultrafast dynamics in minor groove recognition (2003)
Pal, Samir Kumar, Zhao, Liang, Zewail, Ahmed H.
Water molecules at the surface of DNA are critical to its equilibrium structure, DNA–protein function, and DNA–ligand recognition. Here we report direct probing of the dynamics of hydration, with...
FEMTOSECOND CORRELATION SPECTROSCOPY (2003)
Zhong, Dongping, Zewail, Ahmed H.
Author Institution: Departments of Physics, Chemistry and Biochemistry, The Ohio State University; Laboratory for Molecular Sciences, Arthur Amos Noyes Laboratory of Chemical Physics, California...
Pal, Samir Kumar, Peon, Jorge, Zewail, Ahmed H.
We report studies of hydration dynamics at the surface of the enzyme protein bovine pancreatic {alpha}-chymotrypsin. The probe is the well known 1-anilinonaphthalene-8-sulfonate, which binds...
Hydration at the surface of the protein Monellin: Dynamics with femtosecond resolution (2002)
Peon, Jorge, Pal, Sumir Kumar, Zewail, Ahmed H.
We have studied the femtosecond hydration dynamics of Monellin, a protein with a single tryptophan residue at its surface. Tryptophan was selectively used as a probe of the dynamics, and through...
Zou, Shouzhong, Baskin, J. Spencer, Zewail, Ahmed H.
Molecular recognition by biological macromolecules involves many elementary steps, usually convoluted by diffusion processes. Here we report studies of the dynamics, from the femtosecond to the...
Pal, Samir Kumar, Peon, Jorge, Zewail, Ahmed H.
Biological water at the interface of proteins is critical to their equilibrium structures and enzyme function and to phenomena such as molecular recognition and protein-protein interactions. To...
Zhong, Dongping, Pal, Sumir Kumar, Zhang, Deqiang, Chan, Sunney I., Zewail, Ahmed H.
We report here studies of tryptophan (Trp) solvation dynamics in water and in the Pyrococcus furiosus rubredoxin protein, including the native and its apo and denatured forms. We also report results...
Qu, Xiaogang, Wan, Chaozhi, Becker, Hans-Christian, Zhong, Dongping, Zewail, Ahmed H.
The anthracycline-DNA complex, which is a potent agent for cancer chemotherapy, has a unique intercalating molecular structure with preference to the GC bases of DNA, as shown by Rich's group in...
Zhong, Dongping, Pal, Samir Kumar, Wan, Chaozhi, Zewail, Ahmed H.
In this contribution, we report studies of the primary dynamics of the drug-protein complexes of daunomycin with apo riboflavin-binding protein. With femtosecond resolution, we observed the ultrafast...
Zhong, Dongping, Zewail, Ahmed H.
Flavoproteins can function as hydrophobic sites for vitamin B2 (riboflavin) or, in other structures, with cofactors for catalytic reactions such as glucose oxidation. In this contribution, we report...
Ruan, Chong-Yu, Lobastov, Vladimir A., Srinivasan, Ramesh, Goodson, Boyd M., Ihee, Hyotcherl, Zewail, Ahmed H.
Studies of molecular structures at or near their equilibrium configurations have long provided information on their geometry in terms of bond distances and angles. Far-from-equilibrium structures are...
Femtosecond studies of protein-ligand hydrophobic binding and dynamics: Human serum albumin (2000)
Zhong, Dongping, Douhal, Abderrazzak, Zewail, Ahmed H.
In this contribution, we report studies of the nature of the dynamics and hydrophobic binding in protein-ligand complexes of human serum albumin with 2-(2'-hydroxyphenyl)-4-methyloxazole. With...
Femtosecond direct observation of charge transfer between bases in DNA (2000)
Wan, Chaozhi, Fiebig, Torsten, Schiemann, Olav, Barton, Jacqueline K., Zewail, Ahmed H.
Charge transfer in supramolecular assemblies of DNA is unique because of the notion that the pi-stacked bases within the duplex may mediate the transport, possibly leading to damage and/or repair....
Önfelt, Björn, Lincoln, Per, Nordén, Bengt, Baskin, J. Spencer, Zewail, Ahmed H.
The DNA-intercalating chromophore [Ru(phen)2dppz]2+ has unique photophysical properties, the most striking of which is the "light-switch" characteristic when binding to DNA. As a dimer, it acts as a...
Diau, Eric W.-G., Casanova, Joseph, Roberts, John D., Zewail, Ahmed H.
In this communication, we report our femtosecond real-time observation of the dynamics for the three didehydrobenzene molecules (p-, m-, and o-benzyne) generated from 1,4-, 1,3-, and...
Femtosecond dynamics of hydrogen elimination: benzene formation from cyclohexadiene (2000)
De Feyter, Steven, Diau, Eric W.-G., Zewail, Ahmed H.
Using femtosecond-resolved mass spectrometry in a molecular beam, we report real-time study of the hydrogen elimination reaction of 1,4-cyclohexadiene. The experimental observation of the ultrafast...
Femtosecond dynamics of DNA-mediated electron transfer (1999)
Wan, Chaozhi, Fiebig, Torsten, Kelley, Shana O., Treadway, Christopher R., Barton, Jacqueline K., Zewail, Ahmed H.
Diverse biophysical and biochemical studies have sought to understand electron transfer (ET) in DNA in part because of its importance to DNA damage and its repair. However, the dynamics and...
Zhong, Dongping, Zewail, Ahmed H.
With fs time, speed, and angular resolution of the elementary steps in electron transfer reactions, we report direct observation of reversible and dissociative processes for dative bonding involving...
Fiebig, Torsten, Wan, Chaozhi, Kelley, Shana O., Barton, Jacqueline K., Zewail, Ahmed H.
Ethidium (E) is a powerful probe of DNA dynamics and DNA-mediated electron transfer (ET). Molecular dynamical processes, such as solvation and orientation, are important on the time scale of ET....
Cao, Jianming, Ihee, Hyotcherl, Zewail, Ahmed H.
Ultrafast electron diffraction is a unique method for the studies of structural changes of complex molecular systems. In this contribution, we report direct ultrafast electron diffraction study of...
Ultrafast Chemical Dynamics of Reactions in Beams. (1998)
The purpose of this research was to initiate the field of femtochemistry by interfacing state-of-the-art femtosecond laser systems to a beam system. This plan allowed us to study, for the first time,...
Ultrafast Dynamics of Chemical Reactions (1998)
The research in this proposal focused on the development of femtosecond laser techniques and their applications in the studies of molecular dynamics in real time. The research culminated in some...
Femtosecond Dynamics of Chemical Reactions (1998)
We proposed to use this grant to undertake research in the following three major areas: (a) Dynamics of elementary steps in complex systems. (b) Dynamics of reactions under extreme environment...
The research was focused on two major areas. The first area is the advancement of new techniques to elucidate elementary steps of reactions in complex molecular systems. In the second area, the...
Ultrafast Dynamics of Chemical Reactions. (1997)
The research and efforts mentioned above describe our accomplishments and new findings in three areas: (a) fundamental R/D; (b) new technologies and techniques; and (c) educational and training of...
Theoretical Studies of the Rydberg State Predissociation of Methyl Iodide (1994)
$^{1}$. M. H. M. Janssen, M. Dantus, H. Guo and A. H. Zewail, Chem. Phys. Lett., 214, 281 (1993).
Femtosecond transition-state dynamics (1991)
This article presents the progress made in probing femtosecond transition–state dynamics of elementary reactions. Experiments demonstrating the dynamics in systems characterized by a transition...
Ultrafast molecular reaction dynamics in real-time: progress over a decade (1990)
Khundkar, Lutfur R., Zewail, Ahmed H.
One of the goals of researchers in the field of reaction dynamics is to develop an understanding of the elementary steps involved in a chemical reaction on a molecular level (see e.g. Ref. 1). The...
Femtosecond real-time probing of reactions. IV. The reactions of alkali halides (1989)
Rose, Todd S., Rosker, Mark J., Zewail, Ahmed H.
The photodissociation dynamics of some alkali halides are explored via the method of femtosecond transition-state spectroscopy (FTS). The alkali halide dissociation reaction is influenced by the...
Femtochemistry: the role of alignment and orientation (1989)
Some aspects of alignment and orientation have been considered for femtochemistry experiments. Elementary theoretical descriptions of the time evolution of alignment and angular momenta have been...
Bernstein, Richard B., Zewail, Ahmed H.
Femtosecond transition-state spectroscopy (FTS) of elementary reactions [M. Dantus, M. J. Rosker, and A. H. Zewail, J. Chem. Phys. 87, 2395 (1987)] provides real-time observations of photofragments...
Practical Broad-Band Tuning of Dye Lasers by Solvent Shifting (1986)
Grenci, Susan M., Bird, George R., Keelan, Brian W., Zewail, Ahmed H.
We have operated a dye laser over a broad wavelength range (593.8-667.0nm) by shifting the dye emission profile with incremental changes of solvent composition. This was accomplished with the laser...
The development of the picosecond-jet technique is presented. The applications of the technique to the studies of coherence (quantum beats), photodissociation, isomerization and partial solvation of...
Picosecond Laser Chemistry in Supersonic Jet Beams (1983)
In this review we describe the development and the applications of the picosecond-jet technique, which utilizes a picosecond laser and a supersonically-cold jet beam of large molecules. The...
Phase Coherence in Multiple Pulse Optical Spectroscopy (1983)
Warren, Warren S., Zewail, Ahmed H.
In this paper we describe a new technique for the generation of multiple pulse phase coherent sequences in optical spectroscopy. The technique is an extension of the acousto-optic modulation and...
Thesis (Ph. D.)--University of Pennsylvania, 1975.
LOW AND ZERO FIELD MAGNETIC RESONANCE AND OPTICAL STUDIES OF ORGANIC KETONES (1973)
Hochstrasser, Robin M., Scott, Gary W., Zewail, Ahmed H.
$^{1}$ R.M. Hochstrasser, G.W. Scott and A.H. Zewail, J. Chem. Phys. 58, 393 (1973).
Ultrafast electron diffraction and direct observation of transient structures in a chemical reaction
Cao, Jianming, Ihee, Hyotcherl, Zewail, Ahmed H.
Ultrafast electron diffraction is a unique method for the studies of structural changes of complex molecular systems. In this contribution, we report direct ultrafast electron diffraction study of...
Fiebig, Torsten, Wan, Chaozhi, Kelley, Shana O., Barton, Jacqueline K., Zewail, Ahmed H.
Ethidium (E) is a powerful probe of DNA dynamics and DNA-mediated electron transfer (ET). Molecular dynamical processes, such as solvation and orientation, are important on the time scale of ET....
Zhong, Dongping, Zewail, Ahmed H.
With fs time, speed, and angular resolution of the elementary steps in electron transfer reactions, we report direct observation of reversible and dissociative processes for dative bonding involving...
Önfelt, Björn, Lincoln, Per, Nordén, Bengt, Baskin, J. Spencer, Zewail, Ahmed H.
The DNA-intercalating chromophore [Ru(phen)2dppz]2+ has unique photophysical properties, the most striking of which is the “light-switch” characteristic when binding to DNA. As a dimer, it acts...
Femtosecond direct observation of charge transfer between bases in DNA
Wan, Chaozhi, Fiebig, Torsten, Schiemann, Olav, Barton, Jacqueline K., Zewail, Ahmed H.
Charge transfer in supramolecular assemblies of DNA is unique because of the notion that the π-stacked bases within the duplex may mediate the transport, possibly leading to damage and/or repair....
Femtosecond studies of protein–ligand hydrophobic binding and dynamics: Human serum albumin
Zhong, Dongping, Douhal, Abderrazzak, Zewail, Ahmed H.
In this contribution, we report studies of the nature of the dynamics and hydrophobic binding in protein–ligand complexes of human serum albumin with 2-(2′-hydroxyphenyl)-4-methyloxazole. With...
Diau, Eric W.-G., Casanova, Joseph, Roberts, John D., Zewail, Ahmed H.
In this communication, we report our femtosecond real-time observation of the dynamics for the three didehydrobenzene molecules (p-, m-, and o-benzyne) generated from 1,4-, 1,3-, and...
Femtosecond dynamics of DNA-mediated electron transfer
Wan, Chaozhi, Fiebig, Torsten, Kelley, Shana O., Treadway, Christopher R., Barton, Jacqueline K., Zewail, Ahmed H.
Diverse biophysical and biochemical studies have sought to understand electron transfer (ET) in DNA in part because of its importance to DNA damage and its repair. However, the dynamics and...
Ultrafast diffraction and structural dynamics: The nature of complex molecules far from equilibrium
Ruan, Chong-Yu, Lobastov, Vladimir A., Srinivasan, Ramesh, Goodson, Boyd M., Ihee, Hyotcherl, Zewail, Ahmed H.
Studies of molecular structures at or near their equilibrium configurations have long provided information on their geometry in terms of bond distances and angles. Far-from-equilibrium structures are...
Zhong, Dongping, Zewail, Ahmed H.
Flavoproteins can function as hydrophobic sites for vitamin B2 (riboflavin) or, in other structures, with cofactors for catalytic reactions such as glucose oxidation. In this contribution, we report...