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144 results on '"Gaffney, K J"'

1. Probing ultrafast \pi\pi*/n\pi* internal conversion in organic chromophores via K-edge resonant absorption

Author

Wolf, T. J. A., Myhre, R. H., Cryan, J. P., Coriani, S., Squibb, R. J., Battistoni, A., Berrah, N., Bostedt, C., Bucksbaum, P., Coslovich, G., Feifel, R., Gaffney, K. J., Grilj, J., Martinez, T. J., Miyabe, S., Moeller, S. P., Mucke, M., Natan, A., Obaid, R., Osipov, T., Plekan, O., Wang, S., Koch, H., and Gühr, M.

Subjects
Physics - Chemical Physics
Abstract

Organic chromophores with heteroatoms possess an important excited state relaxation channel from an optically allowed {\pi}{\pi}* to a dark n{\pi}*state. We exploit the element and site specificity of soft x-ray absorption spectroscopy to selectively follow the electronic change during the {\pi}{\pi}*/n{\pi}* internal conversion. As a hole forms in the n orbital during {\pi}{\pi}*/n{\pi}* internal conversion, the near edge x-ray absorption fine structure (NEXAFS) spectrum at the heteroatom K-edge exhibits an additional resonance. We demonstrate the concept with the nucleobase thymine, a prototypical heteroatomic chromophore. With the help of time resolved NEXAFS spectroscopy at the oxygen K-edge, we unambiguously show that {\pi}{\pi}*/n{\pi}* internal conversion takes place within (60 \pm 30) fs. High-level coupled cluster calculations on the isolated molecules used in the experiment confirm the superb electronic structure sensitivity of this new method for excited state investigations.

Published
2016
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2. Atomic-Scale Visualization of Inertial Dynamics

Author

Lindenberg, A. M., Larsson, J., Sokolowski-Tinten, K., Gaffney, K. J., Blome, C., Synnergren, O., Sheppard, J., Caleman, C., MacPhee, A. G., Weinstein, D., Lowney, D. P., Allison, T. K., Matthews, T., Falcone, R. W., Cavalieri, A. L., Fritz, D. M., Lee, S. H., Bucksbaum, P. H., Reis, D. A., Rudati, J., Fuoss, P. H., Kao, C. C., Siddons, D. P., Pahl, R., Als-Nielsen, J., Duesterer, S., Ischebeck, R., Schlarb, H., Schulte-Schrepping, H., Schneider, J., von der Linde, D., Hignette, O., Sette, F., Chapman, H. N., Lee, R. W., Hansen, T. N., Techert, S., Wark, J. S., Bergh, M., Huldt, G., van der Spoel, D., Timneanu, N., Hajdu, J., Akre, R. A., Bong, E., Krejcik, P., Arthur, J., Brennan, S., Luening, K., and Hastings, J. B.

Published
2005

10. Ultrafast Bond Softening in Bismuth: Mapping a Solid's Interatomic Potential with X-Rays

Author

Fritz, D. M., Reis, D. A., Adams, B., Akre, R. A., Arthur, J., Blome, C., Bucksbaum, P. H., Cavalieri, A. L., Engemann, S., Fahy, S., Falcone, R. W., Fuoss, P. H., Gaffney, K. J., George, M. J., Hajdu, J., Hertlein, M. P., Hillyard, P. B., Hoegen, M. Horn-von, Kammler, M., Kaspar, J., Kienberger, R., Krejcik, P., Lee, S. H., Lindenberg, A. M., McFarland, B., Meyer, D., Montagne, T., Murray, É. D., Nelson, A. J., Nicoul, M., Pahl, R., Rudati, J., Schlarb, H., Siddons, D. P., Sokolowski-Tinten, K., Tschentscher, Th., von der Linde, D., and Hastings, J. B.

Published
2007
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11. Excited Electron Dynamics at Benzene/Ag(111)

Author

Harris, C. B., McNeill, J. D., Ge, N.-H., Wong, C. M., Gaffney, K. J., Liu, S. H., Miller, A. D., Schäfer, F. P., editor, Toennies, J. P., editor, Zinth, Wolfgang, editor, Elsaesser, Thomas, Fujimoto, James G., and Wiersma, Douwe A.

Published
1998
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14. Hydrogen bond breaking and reformation in alcohol oligomers following vibrational relaxation of a non-hydrogen-bond donating hydroxyl stretch

Author

Gaffney, K. J., Piletic, I. R., and Fayer, M. D.

Subjects
Hydrogen bonding -- Research, Oligomers -- Research, Alcohols -- Chemical properties, Chemicals, plastics and rubber industries
Abstract

The vibrational relaxation in methanol-d, ethanol-d, and 1-propanol-d dissolved in CCl4 calculated with ultra-fast infrared pump-probe experiment is presented. A model in which hydrogen bond dissociation, subsequent to vibrational relaxation, raises the concentration of non-hydrogen bond donating hydroxyl clusters.

Published
2002

17. Evolution of a two-dimensional band structure at a self-assembling interface

Author

Miller, A. D., Gaffney, K. J., Liu, S. H., Szymanski, P., Harris, C. B., Garrett-Roe, S., and Wong, C. M.

Subjects
Methane -- Research, Photons -- Usage, Photoemission -- Usage, Chemicals, plastics and rubber industries
Abstract

The interfacial band structure of the methanethiolate/Ag(111) interface is studied using two-photon photoemisssion. Two adsorbate-induced electronic states, occupied and unoccupied excited state are observed.

Published
2002

18. LCLS Ultrafast Science Instruments:Conceptual Design Report

Author

Arthur, J., primary, Boutet, S., additional, Castagna, J-C., additional, Chapman, H., additional, Feng, Y., additional, Foyt, W., additional, Fritz, D. M., additional, Gaffney, K. J., additional, Gruebel, G., additional, Hajdu, J., additional, Hastings, J. B., additional, Kurita, N., additional, Larsson, J., additional, Ludwig, K., additional, Messerschmidt, M., additional, Miao, J., additional, Reis, D. A., additional, Robert, A., additional, Stephenson, G. B., additional, Tschentscher, Th., additional, and van Bakel, N., additional

Published
2007
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19. Photodissociation of aqueous I3− observed with liquid-phase ultrafast mega-electron-volt electron diffraction.

Author

Ledbetter, K., Biasin, E., Nunes, J. P. F., Centurion, M., Gaffney, K. J., Kozina, M., Lin, M.-F., Shen, X., Yang, J., Wang, X. J., Wolf, T. J. A., and Cordones, A. A.

Subjects
PHOTODISSOCIATION, ELECTRON diffraction, ELECTRON sources, STRUCTURAL dynamics, LASER pulses, VACUUM
Abstract

Developing femtosecond resolution methods for directly observing structural dynamics is critical to understanding complex photochemical reaction mechanisms in solution. We have used two recent developments, ultrafast mega-electron-volt electron sources and vacuum compatible sub-micron thick liquid sheet jets, to enable liquid-phase ultrafast electron diffraction (LUED). We have demonstrated the viability of LUED by investigating the photodissociation of tri-iodide initiated with a 400 nm laser pulse. This has enabled the average speed of the bond expansion to be measured during the first 750 fs of dissociation and the geminate recombination to be directly captured on the picosecond time scale. [ABSTRACT FROM AUTHOR]

Published
2020
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20. Structural dynamics of hydrogen bonded methanol oligomers: Vibrational transient hole burning studies of spectral diffusion.

Author

Piletic, I. R., Gaffney, K. J., and Fayer, M. D.

Subjects
*METHANOL, *OLIGOMERS, *DIFFUSION, *ABSORPTION, *SOLUTION (Chemistry), *MOLECULAR spectroscopy
Abstract

Frequency resolved pump-probe experiments have been conducted on the deuterated hydroxyl stretch of methanol-d in a solution containing 0.8% methanol-d/23% methanol-h in carbon tetrachloride. Methanol-d molecules that both donate and receive hydrogen bonds have an inhomogeneously broadened hydroxyl stretch absorption line centered at 2487 cm[SUP-1]. With a laser tuned to 2513 cm[SUP-1], the high-frequency side of the absorption spectrum is excited. The equilibration of the excited state peak and the ground-state hole results in the time-dependent shift in the frequency of the signal, which is used to monitor the dynamics of spectral diffusion. Model calculations were conducted to address the influence of spectral diffusion in the ground and excited states on the experimental observables when the vibrational lifetime is comparable to the spectral diffusion time. The model calculations illustrate the influence on the signal of absorbers in the ground state that have relaxed from the excited state. This aspect of the problem has not been addressed in previous descriptions of frequency resolved pump-probe spectroscopy. The calculations were used to fit the time-dependent peak maximum, resulting in a bi-exponential frequency-frequency correlation function, with a fast time constant of roughly 0.1 ps and a slower time constant of 1.6 ± 0.3 ps. The observed dynamics have been compared with the predictions of dielectric continuum theory. The inability of a simple dielectric continuum theory to predict the observed spectral diffusion dynamics suggests that these dynamics do not result from the long-wavelength, collective orientational relaxation of the solvent. Instead the dynamics are attributed to fluctuations in the local hydrogen bond network, which is consistent with recent molecular-dynamics simulations of vibrational transient hole burning in water. [ABSTRACT FROM AUTHOR]

Published
2003
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21. Orientational relaxation and vibrational excitation transfer in methanol–carbon tetrachloride solutions.

Author

Gaffney, K. J., Piletic, I. R., and Fayer, M. D.

Subjects
*RELAXATION (Nuclear physics), *VIBRATIONAL spectra
Abstract

Time and polarization resolved ultrafast infrared vibrational spectroscopy of the hydroxyl stretch of methanol dissolved in carbon tetrachloride has been utilized to investigate orientational relaxation and vibrational excitation transfer. The anisotropy decay of the deuterated hydroxyl stretch of methanol-d was measured in two solutions: Isotopically mixed 0.8 mol % methanol-d 23 mol % methanol-h in CCl[SUB4] and isotopically pure methanol-dat 26 mol % in CCl[SUB4]. The anisotropy decay in the isotopically mixed methanol solution is a biexponential characterized by 1.7±0.7 ps and 17±3 ps time constants, with 40±10% of the decay occurring with the slower time constant. The biexponential anisotropy decay has been analyzed with a restricted orientational diffusion model that involves fast orientational diffusion within a cone of semi-angle Θ[SUBc] followed by slower, full orientational relaxation. The fast orientational relaxation occurs within a cone semi-angle of Θ[SUBc]=45°±5°, with a diffusion coefficient of D[SUP-1,SUBc]=13±5 ps. The slower anisotropy decay results from the full orientational diffusion and occurs with a diffusion coefficient of D[SUP-1,SUBTheta;]=100±20 ps. The anisotropy decay for isotopically pure methanol-d in CCl[SUB4] is much faster because of vibrational excitation transfer in addition to the orientational relaxation. The excitation transfer has been successfully analyzed as transition dipole-transition dipole mediated transfer using a theory developed for randomly distributed chromophores. [ABSTRACT FROM AUTHOR]

Published
2003
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22. Probing ultrafast ����*/n��* internal conversion in organic chromophores via K-edge resonant absorption

Author

Wolf, T. J. A., Myhre, R. H., Cryan, J. P., Coriani, S., Squibb, R. J., Battistoni, A., Berrah, N., Bostedt, C., Bucksbaum, P., Coslovich, G., Feifel, R., Gaffney, K. J., Grilj, J., Martinez, T. J., Miyabe, S., Moeller, S. P., Mucke, M., Natan, A., Obaid, R., Osipov, T., Plekan, O., Wang, S., Koch, H., and G��hr, M.

Subjects
Chemical Physics (physics.chem-ph), FOS: Physical sciences
Abstract

Organic chromophores with heteroatoms possess an important excited state relaxation channel from an optically allowed ����* to a dark n��*state. We exploit the element and site specificity of soft x-ray absorption spectroscopy to selectively follow the electronic change during the ����*/n��* internal conversion. As a hole forms in the n orbital during ����*/n��* internal conversion, the near edge x-ray absorption fine structure (NEXAFS) spectrum at the heteroatom K-edge exhibits an additional resonance. We demonstrate the concept with the nucleobase thymine, a prototypical heteroatomic chromophore. With the help of time resolved NEXAFS spectroscopy at the oxygen K-edge, we unambiguously show that ����*/n��* internal conversion takes place within (60 \pm 30) fs. High-level coupled cluster calculations on the isolated molecules used in the experiment confirm the superb electronic structure sensitivity of this new method for excited state investigations.

Published
2016
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23. Probing ultrafast ππ*/nπ* internal conversion in organic chromophores via K-edge resonant absorption

Author

Wolf, T. J. A., primary, Myhre, R. H., additional, Cryan, J. P., additional, Coriani, S., additional, Squibb, R. J., additional, Battistoni, A., additional, Berrah, N., additional, Bostedt, C., additional, Bucksbaum, P., additional, Coslovich, G., additional, Feifel, R., additional, Gaffney, K. J., additional, Grilj, J., additional, Martinez, T. J., additional, Miyabe, S., additional, Moeller, S. P., additional, Mucke, M., additional, Natan, A., additional, Obaid, R., additional, Osipov, T., additional, Plekan, O., additional, Wang, S., additional, Koch, H., additional, and Gühr, M., additional

Published
2017
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24. Probing molecular photoinduced dynamics by ultrafast soft x-rays

Author

Wolf, T. J. A., primary, Myhre, R. H., additional, Cryan, J. P., additional, Coriani, S., additional, Squibb, R. J., additional, Battistoni, A., additional, Berrah, N., additional, Bostedt, C., additional, Bucksbaum, P., additional, Coslovich, G., additional, Feifel, R., additional, Gaffney, K. J., additional, Grilj, J., additional, Martinez, T. J., additional, Miyabe, S., additional, Moeller, S. P., additional, Mucke, M., additional, Natan, A., additional, Obaid, R., additional, Osipov, T., additional, Plekan, O., additional, Wang, S., additional, Koch, H., additional, and Guhr, M., additional

Published
2017
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Author

Wolf, T. J. A., Myhre, Rolf H., Cryan, J. P., Coriani, Sonia, Squibb, R. J., Battistoni, A., Berrah, N., Bostedt, C., Bucksbaum, P., Coslovich, G., Feifel, R., Gaffney, K. J., Grilj, J., Martinez, T. J., Miyabe, S., Moeller, S. P., Mucke, M., Natan, A., Obaid, R., Osipov, T., Plekan, O., Wang, S., Koch, H., Güehr, M., Wolf, T. J. A., Myhre, Rolf H., Cryan, J. P., Coriani, Sonia, Squibb, R. J., Battistoni, A., Berrah, N., Bostedt, C., Bucksbaum, P., Coslovich, G., Feifel, R., Gaffney, K. J., Grilj, J., Martinez, T. J., Miyabe, S., Moeller, S. P., Mucke, M., Natan, A., Obaid, R., Osipov, T., Plekan, O., Wang, S., Koch, H., and Güehr, M.

Published
2017

26. Probing molecular photoinduced dynamics by ultrafast soft x-rays

Author

Wolf, T. J. A., Myhre, R. H., Cryan, J. P., Coriani, S., Squibb, R. J., Battistoni, A., Berrah, N., Bostedt, C., Bucksbaum, P., Coslovich, G., Feifel, R., Gaffney, K. J., Grilj, J., Martinez, T. J., Miyabe, S., Moeller, S. P., Mucke, Melanie, Natan, A., Obaid, R., Osipov, T., Plekan, O., Wang, S., Koch, H., Guehr, M., Wolf, T. J. A., Myhre, R. H., Cryan, J. P., Coriani, S., Squibb, R. J., Battistoni, A., Berrah, N., Bostedt, C., Bucksbaum, P., Coslovich, G., Feifel, R., Gaffney, K. J., Grilj, J., Martinez, T. J., Miyabe, S., Moeller, S. P., Mucke, Melanie, Natan, A., Obaid, R., Osipov, T., Plekan, O., Wang, S., Koch, H., and Guehr, M.

Published
2017
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27. Probing ultrafast pi pi*/n pi* internal conversion in organic chromophores via K-edge resonant absorption

Author

Wolf, T. J. A., Myhre, R. H., Cryan, J. P., Coriani, S., Squibb, R. J., Battistoni, A., Berrah, N., Bostedt, C., Bucksbaum, P., Coslovich, G., Feifel, R., Gaffney, K. J., Grilj, J., Martinez, T. J., Miyabe, S., Moeller, S. P., Mucke, Melanie, Natan, A., Obaid, R., Osipov, T., Plekan, O., Wang, S., Koch, H., Gühr, M., Wolf, T. J. A., Myhre, R. H., Cryan, J. P., Coriani, S., Squibb, R. J., Battistoni, A., Berrah, N., Bostedt, C., Bucksbaum, P., Coslovich, G., Feifel, R., Gaffney, K. J., Grilj, J., Martinez, T. J., Miyabe, S., Moeller, S. P., Mucke, Melanie, Natan, A., Obaid, R., Osipov, T., Plekan, O., Wang, S., Koch, H., and Gühr, M.

Abstract

Many photoinduced processes including photosynthesis and human vision happen in organic molecules and involve coupled femtosecond dynamics of nuclei and electrons. Organic molecules with heteroatoms often possess an important excited-state relaxation channel from an optically allowed pi pi* to a dark n pi* state. The pi pi*/n pi* internal conversion is difficult to investigate, as most spectroscopic methods are not exclusively sensitive to changes in the excited-state electronic structure. Here, we report achieving the required sensitivity by exploiting the element and site specificity of near-edge soft X-ray absorption spectroscopy. As a hole forms in the n orbital during pi pi*/n pi* internal conversion, the absorption spectrum at the heteroatom K-edge exhibits an additional resonance. We demonstrate the concept using the nucleobase thymine at the oxygen K-edge, and unambiguously show that pi pi*/n pi* internal conversion takes place within (60 +/- 30) fs. High-level-coupled cluster calculations confirm the method's impressive electronic structure sensitivity for excited-state investigations.

Published
2017
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28. Identification of the dominant photochemical pathways and mechanistic insights to the ultrafast ligand exchange of Fe(CO)5 to Fe(CO)4EtOH

Author

Kunnus, K., Josefsson, I., Rajkovic, I., Schreck, S., Quevedo, W., Beye, M., Weniger, C., Grübel, S., Scholz, M., Nordlund, D., Zhang, W., Hartsock, R. W., Gaffney, K. J., Schlotter, W. F., Turner, J. J., Kennedy, B., Hennies, F., De Groot, F. M F, Techert, S., Odelius, M., Wernet, Ph, Föhlisch, A., Kunnus, K., Josefsson, I., Rajkovic, I., Schreck, S., Quevedo, W., Beye, M., Weniger, C., Grübel, S., Scholz, M., Nordlund, D., Zhang, W., Hartsock, R. W., Gaffney, K. J., Schlotter, W. F., Turner, J. J., Kennedy, B., Hennies, F., De Groot, F. M F, Techert, S., Odelius, M., Wernet, Ph, and Föhlisch, A.

Abstract

We utilized femtosecond time-resolved resonant inelastic X-ray scattering and ab initio theory to study the transient electronic structure and the photoinduced molecular dynamics of a model metal carbonyl photocatalyst Fe(CO)5 in ethanol solution. We propose mechanistic explanation for the parallel ultrafast intra-molecular spin crossover and ligation of the Fe(CO)4 which are observed following a charge transfer photoexcitation of Fe(CO)5 as reported in our previous study [Wernet et al., Nature 520, 78 (2015)]. We find that branching of the reaction pathway likely happens in the 1A1 state of Fe(CO)4. A sub-picosecond time constant of the spin crossover from 1B2 to 3B2 is rationalized by the proposed 1B2 → 1A1 → 3B2 mechanism. Ultrafast ligation of the 1B2 Fe(CO)4 state is significantly faster than the spin-forbidden and diffusion limited ligation process occurring from the 3B2 Fe(CO)4 ground state that has been observed in the previous studies. We propose that the ultrafast ligation occurs via 1B2 → 1A1 → 1A' Fe(CO)4EtOH pathway and the time scale of the 1A1 Fe(CO)4 state ligation is governed by the solute-solvent collision frequency. Our study emphasizes the importance of understanding the interaction of molecular excited states with the surrounding environment to explain the relaxation pathways of photoexcited metal carbonyls in solution.

Published
2016

29. Identification of the dominant photochemical pathways and mechanistic insights to the ultrafast ligand exchange of Fe(CO)5 to Fe(CO)4EtOH

Author

Sub Inorganic Chemistry and Catalysis, Inorganic Chemistry and Catalysis, Kunnus, K., Josefsson, I., Rajkovic, I., Schreck, S., Quevedo, W., Beye, M., Weniger, C., Grübel, S., Scholz, M., Nordlund, D., Zhang, W., Hartsock, R. W., Gaffney, K. J., Schlotter, W. F., Turner, J. J., Kennedy, B., Hennies, F., De Groot, F. M F, Techert, S., Odelius, M., Wernet, Ph, Föhlisch, A., Sub Inorganic Chemistry and Catalysis, Inorganic Chemistry and Catalysis, Kunnus, K., Josefsson, I., Rajkovic, I., Schreck, S., Quevedo, W., Beye, M., Weniger, C., Grübel, S., Scholz, M., Nordlund, D., Zhang, W., Hartsock, R. W., Gaffney, K. J., Schlotter, W. F., Turner, J. J., Kennedy, B., Hennies, F., De Groot, F. M F, Techert, S., Odelius, M., Wernet, Ph, and Föhlisch, A.

Published
2016

30. Initial metal–metal bond breakage detected by fs X-ray scattering in the photolysis of Ru3(CO)12 in cyclohexane at 400 nm.

Author

Kong, Q. Y., Laursen, M. G., Haldrup, K., Kjær, K. S., Khakhulin, D., Biasin, E., van Driel, T. B., Wulff, M., Kabanova, V., Vuilleumier, R., Bratos, S., Nielsen, M. M., Gaffney, K. J., Weng, T. C., and Koch, M. H. J.

Subjects
METAL bonding, X-ray scattering, PHOTOLYSIS (Chemistry), CYCLOHEXANE, RUTHENIUM compounds
Abstract

Using femtosecond resolution X-ray solution scattering at a free electron laser we were able to directly observe metal–metal bond cleavage upon photolysis at 400 nm of Ru3(CO)12, a prototype for the photochemistry of transition metal carbonyls. This leads to the known single intermediate Ru3(CO)11(μ-CO)*, with a bridging ligand (μCO) and where the asterisk indicates an open Ru3-ring. This loses a CO ligand on a picosecond time scale yielding a newly observed triple bridge intermediate, Ru3(CO)8(μ-CO)3*. This loses another CO ligand to form the previously observed Ru3(CO)10, which returns to Ru3(CO)12via the known single-bridge Ru3(CO)10(μ-CO). These results indicate that contrary to long standing hypotheses, metal–metal bond breakage is the only chemical reaction immediately following the photolysis of Ru3(CO)12 at 400 nm. Combined with previous picosecond resolution X-ray scattering data and time resolved infrared spectroscopy these results yield a new mechanism for the photolysis of Ru3(CO)12. [ABSTRACT FROM AUTHOR]

Published
2019
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31. Identification of the dominant photochemical pathways and mechanistic insights to the ultrafast ligand exchange of Fe(CO)5 to Fe(CO)4EtOH

Author

Kunnus, K., primary, Josefsson, I., additional, Rajkovic, I., additional, Schreck, S., additional, Quevedo, W., additional, Beye, M., additional, Weniger, C., additional, Grübel, S., additional, Scholz, M., additional, Nordlund, D., additional, Zhang, W., additional, Hartsock, R. W., additional, Gaffney, K. J., additional, Schlotter, W. F., additional, Turner, J. J., additional, Kennedy, B., additional, Hennies, F., additional, de Groot, F. M. F., additional, Techert, S., additional, Odelius, M., additional, Wernet, Ph., additional, and Föhlisch, A., additional

Published
2016
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32. Orbital-specific mapping of the ligand exchange dynamics of Fe(CO)(5) in solution

Author

Inorganic Chemistry and Catalysis, Sub Inorganic Chemistry and Catalysis, Wernet, Ph., Kunnus, K., Josefsson, I., Rajkovic, I., Quevedo, W., Beye, M., Schreck, S., Gruebel, S., Scholz, M., Nordlund, D., Zhang, W., Hartsock, R. W., Schlotter, W. F., Turner, J. J., Kennedy, B., Hennies, F., de Groot, F. M. F., Gaffney, K. J., Techert, S., Odelius, M., Foehlisch, A., Inorganic Chemistry and Catalysis, Sub Inorganic Chemistry and Catalysis, Wernet, Ph., Kunnus, K., Josefsson, I., Rajkovic, I., Quevedo, W., Beye, M., Schreck, S., Gruebel, S., Scholz, M., Nordlund, D., Zhang, W., Hartsock, R. W., Schlotter, W. F., Turner, J. J., Kennedy, B., Hennies, F., de Groot, F. M. F., Gaffney, K. J., Techert, S., Odelius, M., and Foehlisch, A.

Published
2015

33. Ultrafast X-ray Auger probing of photoexcited molecular dynamics

Author

McFarland, B. K., Farrell, J. P., Miyabe, S., Tarantelli, F., Aguilar, A., Berrah, N., Bostedt, C., Bozek, J. D., Bucksbaum, P. H., Castagna, J. C., Coffee, R. N., Cryan, J. P., Fang, L., Feifel, Raimund, Gaffney, K. J., Glownia, J. M., Martinez, T. J., Mucke, Melanie, Murphy, B., Natan, A., Osipov, T., Petrovic, V. S., Schorb, S., Schultz, Th., Spector, L. S., Swiggers, M., Tenney, I., Wang, S., White, J. L., White, W., Guehr, M., McFarland, B. K., Farrell, J. P., Miyabe, S., Tarantelli, F., Aguilar, A., Berrah, N., Bostedt, C., Bozek, J. D., Bucksbaum, P. H., Castagna, J. C., Coffee, R. N., Cryan, J. P., Fang, L., Feifel, Raimund, Gaffney, K. J., Glownia, J. M., Martinez, T. J., Mucke, Melanie, Murphy, B., Natan, A., Osipov, T., Petrovic, V. S., Schorb, S., Schultz, Th., Spector, L. S., Swiggers, M., Tenney, I., Wang, S., White, J. L., White, W., and Guehr, M.

Abstract

Molecules can efficiently and selectively convert light energy into other degrees of freedom. Disentangling the underlying ultrafast motion of electrons and nuclei of the photoexcited molecule presents a challenge to current spectroscopic approaches. Here we explore the photoexcited dynamics of molecules by an interaction with an ultrafast X-ray pulse creating a highly localized core hole that decays via Auger emission. We discover that the Auger spectrum as a function of photoexcitation-X-ray-probe delay contains valuable information about the nuclear and electronic degrees of freedom from an element-specific point of view. For the nucleobase thymine, the oxygen Auger spectrum shifts towards high kinetic energies, resulting from a particular C-O bond stretch in the pi pi* photoexcited state. A subsequent shift of the Auger spectrum towards lower kinetic energies displays the electronic relaxation of the initial photoexcited state within 200 fs. Ab-initio simulations reinforce our interpretation and indicate an electronic decay to the n pi* state.

Published
2014
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34. Ultrafast X-ray Auger probing of photoexcited molecular dynamics

Author

McFarland, B. K., primary, Farrell, J. P., additional, Miyabe, S., additional, Tarantelli, F., additional, Aguilar, A., additional, Berrah, N., additional, Bostedt, C., additional, Bozek, J. D., additional, Bucksbaum, P. H., additional, Castagna, J. C., additional, Coffee, R. N., additional, Cryan, J. P., additional, Fang, L., additional, Feifel, R., additional, Gaffney, K. J., additional, Glownia, J. M., additional, Martinez, T. J., additional, Mucke, M., additional, Murphy, B., additional, Natan, A., additional, Osipov, T., additional, Petrović, V. S., additional, Schorb, S., additional, Schultz, Th., additional, Spector, L. S., additional, Swiggers, M., additional, Tenney, I., additional, Wang, S., additional, White, J. L., additional, White, W., additional, and Gühr, M., additional

Published
2014
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35. Experimental strategies for optical pump – soft x-ray probe experiments at the LCLS

Author

McFarland, B K, primary, Berrah, N, additional, Bostedt, C, additional, Bozek, J, additional, Bucksbaum, P H, additional, Castagna, J C, additional, Coffee, R N, additional, Cryan, J P, additional, Fang, L, additional, Farrell, J P, additional, Feifel, R, additional, Gaffney, K J, additional, Glownia, J M, additional, Martinez, T J, additional, Miyabe, S, additional, Mucke, M, additional, Murphy, B, additional, Natan, A, additional, Osipov, T, additional, Petrovic, V S, additional, Schorb, S, additional, Schultz, Th, additional, Spector, L S, additional, Swiggers, M, additional, Tarantelli, F, additional, Tenney, I, additional, Wang, S, additional, White, J L, additional, White, W, additional, and Gühr, M, additional

Published
2014
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36. H-bond switching and ligand exchange dynamics in aqueous ionic solution

Author

Gaffney, K. J., Ji, M., Odelius, Michael, Park, S., Sun, Z., Gaffney, K. J., Ji, M., Odelius, Michael, Park, S., and Sun, Z.

Abstract

Aqueous ionic solutions lubricate the chemical machinery of the environment and life. Understanding the impact of ions on the properties of aqueous solutions and how these modified properties influence chemical and conformational dynamics remains an important and elusive objective of physical chemistry research. Here we discuss recent advances in our understanding that have been derived from ultrafast vibrational spectroscopy and molecular dynamics simulations., authorCount :5

Published
2011
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37. X-ray diffuse scattering measurements of nucleation dynamics at femtosecond resolution.

Author

Lindenberg, A. M., Engemann, S., Gaffney, K. J., Sokolowski-Tinten, K., Larsson, J., Hillyard, P. B., Reis, D. A., Fritz, D. M., Arthur, J., Akre, R. A., George, M. J., Deb, A., Bucksbaum, P. H., Hajdu, Janos, Meyer, D. A., Nicoul, M., Blome, C., Tschentscher, Th., Cavalieri, A. L., Falcone, R. W., Lee, S. H., Pahl, R., Rudati, J., Fuoss, P. H., Nelson, A. J., Krejcik, P., Siddons, D. P., Lorazo, P., Hastings, J. B., Lindenberg, A. M., Engemann, S., Gaffney, K. J., Sokolowski-Tinten, K., Larsson, J., Hillyard, P. B., Reis, D. A., Fritz, D. M., Arthur, J., Akre, R. A., George, M. J., Deb, A., Bucksbaum, P. H., Hajdu, Janos, Meyer, D. A., Nicoul, M., Blome, C., Tschentscher, Th., Cavalieri, A. L., Falcone, R. W., Lee, S. H., Pahl, R., Rudati, J., Fuoss, P. H., Nelson, A. J., Krejcik, P., Siddons, D. P., Lorazo, P., and Hastings, J. B.

Abstract

Femtosecond time-resolved small and wide angle x-ray diffuse scattering techniques are applied to investigate the ultrafast nucleation processes that occur during the ablation process in semiconducting materials. Following intense optical excitation, a transient liquid state of high compressibility characterized by large-amplitude density fluctuations is observed and the buildup of these fluctuations is measured in real time. Small-angle scattering measurements reveal snapshots of the spontaneous nucleation of nanoscale voids within a metastable liquid and support theoretical predictions of the ablation process.

Published
2008
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38. Carrier-density-dependent lattice stability in InSb

Author

Hillyard, P. B., Gaffney, K. J., Lindenberg, A. M., Engemann, S., Akre, R. A., Arthur, J., Blome, C., Bucksbaum, P. H., Cavalieri, A. L., Deb, A., Falcone, R. W., Fritz, D. M., Fuoss, P. H., Hajdu, Janos, Krejcik, P., Larsson, J., Lee, S. H., Meyer, D. A., Nelson, A. J., Pahl, R., Reis, D. A., Rudati, J., Siddons, D. P., Sokolowski-Tinten, K., von der Linde, D., Hastings, J. B., Hillyard, P. B., Gaffney, K. J., Lindenberg, A. M., Engemann, S., Akre, R. A., Arthur, J., Blome, C., Bucksbaum, P. H., Cavalieri, A. L., Deb, A., Falcone, R. W., Fritz, D. M., Fuoss, P. H., Hajdu, Janos, Krejcik, P., Larsson, J., Lee, S. H., Meyer, D. A., Nelson, A. J., Pahl, R., Reis, D. A., Rudati, J., Siddons, D. P., Sokolowski-Tinten, K., von der Linde, D., and Hastings, J. B.

Abstract

The ultrafast decay of the x-ray diffraction intensity following laser excitation of an InSb crystal has been utilized to observe carrier dependent changes in the potential energy surface. For the first time, an abrupt carrier dependent onset for potential energy surface softening and the appearance of accelerated atomic disordering for a very high average carrier density have been observed. Inertial dynamics dominate the early stages of crystal disordering for a wide range of carrier densities between the onset of crystal softening and the appearance of accelerated atomic disordering.

Published
2007
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39. Identification of the dominant photochemical pathways and mechanistic insights to the ultrafast ligand exchange of Fe(CO)5 to Fe(CO)4EtOH.

Author

Kunnus, K., Josefsson, I., Rajkovic, I., Schreck, S., Quevedo, W., Beye, M., Weniger, C., Grübel, S., Scholz, M., Nordlund, D., Zhang, W., Hartsock, R. W., Gaffney, K. J., Schlotter, W. F., Turner, J. J., Kennedy, B., Hennies, F., de Groot, F. M. F., Techert, S., and Odelius, M.

Subjects
PHOTOCHEMICAL oxidants, LIGAND exchange reactions, METAL carbonyls
Abstract

We utilized femtosecond time-resolved resonant inelastic X-ray scattering and ab initio theory to study the transient electronic structure and the photoinduced molecular dynamics of a model metal carbonyl photocatalyst Fe(CO)5 in ethanol solution. We propose mechanistic explanation for the parallel ultrafast intra-molecular spin crossover and ligation of the Fe(CO)4 which are observed following a charge transfer photoexcitation of Fe(CO)5 as reported in our previous study [Wernet et al., Nature 520, 78 (2015)]. We find that branching of the reaction pathway likely happens in the 1A1 state of Fe(CO)4. A sub-picosecond time constant of the spin crossover from 1B2 to 3B2 is rationalized by the proposed 1B2 → 1A1 → 3B2 mechanism. Ultrafast ligation of the 1B2 Fe(CO)4 state is significantly faster than the spin-forbidden and diffusion limited ligation process occurring from the 3B2 Fe(CO)4 ground state that has been observed in the previous studies. We propose that the ultrafast ligation occurs via 1B2 → 1A1 → 1A0 Fe(CO)4EtOH pathway and the time scale of the 1A1 Fe(CO)4 state ligation is governed by the solute-solvent collision frequency. Our study emphasizes the importance of understanding the interaction of molecular excited states with the surrounding environment to explain the relaxation pathways of photoexcited metal carbonyls in solution. [ABSTRACT FROM AUTHOR]

Published
2016
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40. Observation of structural anisotropy and the onset of liquidlike motion during the nonthermal melting of InSb.

Author

Gaffney, K J, Lindenberg, A M, Larsson, J, Sokolowski-Tinten, K, Blome, C, Synnergren, O, Sheppard, J, Caleman, C, MacPhee, A G, Weinstein, D, Lowney, D P, Allison, T, Matthews, T, Falcone, R W, Cavalieri, A L, Fritz, D M, Lee, S H, Bucksbaum, P H, Reis, D A, Rudati, J, Macrander, A T, Fuoss, P H, Kao, C C, Siddons, D P, Pahl, R, Moffat, K, Als-Nielsen, J, Duesterer, S, Ischebeck, R, Schlarb, H, Schulte-Schrepping, H, Schneider, J, von der Linde, D, Hignette, O, Sette, F, Chapman, H N, Lee, R W, Hansen, T N, Wark, J S, Bergh, M, Huldt, G, van der Spoel, D, Timneanu, N, Hajdu, J, Akre, R A, Bong, E, Krejcik, P, Arthur, J, Brennan, S, Luening, K, Hastings, J B, Gaffney, K J, Lindenberg, A M, Larsson, J, Sokolowski-Tinten, K, Blome, C, Synnergren, O, Sheppard, J, Caleman, C, MacPhee, A G, Weinstein, D, Lowney, D P, Allison, T, Matthews, T, Falcone, R W, Cavalieri, A L, Fritz, D M, Lee, S H, Bucksbaum, P H, Reis, D A, Rudati, J, Macrander, A T, Fuoss, P H, Kao, C C, Siddons, D P, Pahl, R, Moffat, K, Als-Nielsen, J, Duesterer, S, Ischebeck, R, Schlarb, H, Schulte-Schrepping, H, Schneider, J, von der Linde, D, Hignette, O, Sette, F, Chapman, H N, Lee, R W, Hansen, T N, Wark, J S, Bergh, M, Huldt, G, van der Spoel, D, Timneanu, N, Hajdu, J, Akre, R A, Bong, E, Krejcik, P, Arthur, J, Brennan, S, Luening, K, and Hastings, J B

Published
2005

41. Clocking femtosecond X rays.

Author

Cavalieri, A L, Fritz, D M, Lee, S H, Bucksbaum, P H, Reis, D A, Rudati, J, Mills, D M, Fuoss, P H, Stephenson, G B, Kao, C C, Siddons, D P, Lowney, D P, Macphee, A G, Weinstein, D, Falcone, R W, Pahl, R, Als-Nielsen, J, Blome, C, Düsterer, S, Ischebeck, R, Schlarb, H, Schulte-Schrepping, H, Tschentscher, Th, Schneider, J, Hignette, O, Sette, F, Sokolowski-Tinten, K, Chapman, H N, Lee, R W, Hansen, T N, Synnergren, O, Larsson, J, Techert, S, Sheppard, J, Wark, J S, Bergh, M, Caleman, C, Huldt, G, van der Spoel, D, Timneanu, N, Hajdu, J, Akre, R A, Bong, E, Emma, P, Krejcik, P, Arthur, J, Brennan, S, Gaffney, K J, Lindenberg, A M, Luening, K, Hastings, J B, Cavalieri, A L, Fritz, D M, Lee, S H, Bucksbaum, P H, Reis, D A, Rudati, J, Mills, D M, Fuoss, P H, Stephenson, G B, Kao, C C, Siddons, D P, Lowney, D P, Macphee, A G, Weinstein, D, Falcone, R W, Pahl, R, Als-Nielsen, J, Blome, C, Düsterer, S, Ischebeck, R, Schlarb, H, Schulte-Schrepping, H, Tschentscher, Th, Schneider, J, Hignette, O, Sette, F, Sokolowski-Tinten, K, Chapman, H N, Lee, R W, Hansen, T N, Synnergren, O, Larsson, J, Techert, S, Sheppard, J, Wark, J S, Bergh, M, Caleman, C, Huldt, G, van der Spoel, D, Timneanu, N, Hajdu, J, Akre, R A, Bong, E, Emma, P, Krejcik, P, Arthur, J, Brennan, S, Gaffney, K J, Lindenberg, A M, Luening, K, and Hastings, J B

Abstract

Linear-accelerator-based sources will revolutionize ultrafast x-ray science due to their unprecedented brightness and short pulse duration. However, time-resolved studies at the resolution of the x-ray pulse duration are hampered by the inability to precisely synchronize an external laser to the accelerator. At the Sub-Picosecond Pulse Source at the Stanford Linear-Accelerator Center we solved this problem by measuring the arrival time of each high energy electron bunch with electro-optic sampling. This measurement indirectly determined the arrival time of each x-ray pulse relative to an external pump laser pulse with a time resolution of better than 60 fs rms.

Published
2005

42. Atomic-scale visualization of inertial dynamics.

Author

Lindenberg, A M, Larsson, J, Sokolowski-Tinten, K, Gaffney, K J, Blome, C, Synnergren, O, Sheppard, J, Caleman, C, Macphee, A G, Weinstein, D, Lowney, D P, Allison, T K, Matthews, T, Falcone, R W, Cavalieri, A L, Fritz, D M, Lee, S H, Bucksbaum, P H, Reis, D A, Rudati, J, Fuoss, P H, Kao, C C, Siddons, D P, Pahl, R, Als-Nielsen, J, Duesterer, S, Ischebeck, R, Schlarb, H, Schulte-Schrepping, H, Tschentscher, Th, Schneider, J, von der Linde, D, Hignette, O, Sette, F, Chapman, H N, Lee, R W, Hansen, T N, Techert, S, Wark, J S, Bergh, M, Huldt, G, van der Spoel, D, Timneanu, N, Hajdu, J, Akre, R A, Bong, E, Krejcik, P, Arthur, J, Brennan, S, Luening, K, Hastings, J B, Lindenberg, A M, Larsson, J, Sokolowski-Tinten, K, Gaffney, K J, Blome, C, Synnergren, O, Sheppard, J, Caleman, C, Macphee, A G, Weinstein, D, Lowney, D P, Allison, T K, Matthews, T, Falcone, R W, Cavalieri, A L, Fritz, D M, Lee, S H, Bucksbaum, P H, Reis, D A, Rudati, J, Fuoss, P H, Kao, C C, Siddons, D P, Pahl, R, Als-Nielsen, J, Duesterer, S, Ischebeck, R, Schlarb, H, Schulte-Schrepping, H, Tschentscher, Th, Schneider, J, von der Linde, D, Hignette, O, Sette, F, Chapman, H N, Lee, R W, Hansen, T N, Techert, S, Wark, J S, Bergh, M, Huldt, G, van der Spoel, D, Timneanu, N, Hajdu, J, Akre, R A, Bong, E, Krejcik, P, Arthur, J, Brennan, S, Luening, K, and Hastings, J B

Abstract

The motion of atoms on interatomic potential energy surfaces is fundamental to the dynamics of liquids and solids. An accelerator-based source of femtosecond x-ray pulses allowed us to follow directly atomic displacements on an optically modified energy landscape, leading eventually to the transition from crystalline solid to disordered liquid. We show that, to first order in time, the dynamics are inertial, and we place constraints on the shape and curvature of the transition-state potential energy surface. Our measurements point toward analogies between this nonequilibrium phase transition and the short-time dynamics intrinsic to equilibrium liquids.

Published
2005

46. X-Ray Diffuse Scattering Measurements of Nucleation Dynamics at Femtosecond Resolution

Author

Lindenberg, A. M., primary, Engemann, S., additional, Gaffney, K. J., additional, Sokolowski-Tinten, K., additional, Larsson, J., additional, Hillyard, P. B., additional, Reis, D. A., additional, Fritz, D. M., additional, Arthur, J., additional, Akre, R. A., additional, George, M. J., additional, Deb, A., additional, Bucksbaum, P. H., additional, Hajdu, J., additional, Meyer, D. A., additional, Nicoul, M., additional, Blome, C., additional, Tschentscher, Th., additional, Cavalieri, A. L., additional, Falcone, R. W., additional, Lee, S. H., additional, Pahl, R., additional, Rudati, J., additional, Fuoss, P. H., additional, Nelson, A. J., additional, Krejcik, P., additional, Siddons, D. P., additional, Lorazo, P., additional, and Hastings, J. B., additional

Published
2008
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47. Publisher’s Note: Carrier-Density-Dependent Lattice Stability in InSb [Phys. Rev. Lett.98, 125501 (2007)]

Author

Hillyard, P. B., primary, Gaffney, K. J., additional, Lindenberg, A. M., additional, Engemann, S., additional, Akre, R. A., additional, Arthur, J., additional, Blome, C., additional, Bucksbaum, P. H., additional, Cavalieri, A. L., additional, Deb, A., additional, Falcone, R. W., additional, Fritz, D. M., additional, Fuoss, P. H., additional, Hajdu, J., additional, Krejcik, P., additional, Larsson, J., additional, Lee, S. H., additional, Meyer, D. A., additional, Nelson, A. J., additional, Pahl, R., additional, Reis, D. A., additional, Rudati, J., additional, Siddons, D. P., additional, Sokolowski-Tinten, K., additional, von der Linde, D., additional, and Hastings, J. B., additional

Published
2007
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48. Carrier-Density-Dependent Lattice Stability in InSb

Author

Hillyard, P. B., primary, Gaffney, K. J., additional, Lindenberg, A. M., additional, Engemann, S., additional, Akre, R. A., additional, Arthur, J., additional, Blome, C., additional, Bucksbaum, P. H., additional, Cavalieri, A. L., additional, Deb, A., additional, Falcone, R. W., additional, Fritz, D. M., additional, Fuoss, P. H., additional, Hajdu, J., additional, Krejcik, P., additional, Larsson, J., additional, Lee, S. H., additional, Meyer, D. A., additional, Nelson, A. J., additional, Pahl, R., additional, Reis, D. A., additional, Rudati, J., additional, Siddons, D. P., additional, Sokolowski-Tinten, K., additional, von der Linde, D., additional, and Hastings, J. B., additional

Published
2007
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49. Orbital-specific mapping of the ligand exchange dynamics of Fe(CO)5 in solution.

Author

Wernet, Ph., Kunnus, K., Josefsson, I., Rajkovic, I., Quevedo, W., Beye, M., Schreck, S., Grübel, S., Scholz, M., Nordlund, D., Zhang, W., Hartsock, R. W., Schlotter, W. F., Turner, J. J., Kennedy, B., Hennies, F., de Groot, F. M. F., Gaffney, K. J., Techert, S., and Odelius, M.

Subjects
LIGAND exchange reactions, ORBITAL mechanics, TRANSITION metals, SOLAR energy conversion, CARBON-hydrogen bonds
Abstract

Transition-metal complexes have long attracted interest for fundamental chemical reactivity studies and possible use in solar energy conversion. Electronic excitation, ligand loss from the metal centre, or a combination of both, creates changes in charge and spin density at the metal site that need to be controlled to optimize complexes for photocatalytic hydrogen production and selective carbon-hydrogen bond activation. An understanding at the molecular level of how transition-metal complexes catalyse reactions, and in particular of the role of the short-lived and reactive intermediate states involved, will be critical for such optimization. However, suitable methods for detailed characterization of electronic excited states have been lacking. Here we show, with the use of X-ray laser-based femtosecond-resolution spectroscopy and advanced quantum chemical theory to probe the reaction dynamics of the benchmark transition-metal complex Fe(CO)5 in solution, that the photo-induced removal of CO generates the 16-electron Fe(CO)4 species, a homogeneous catalyst with an electron deficiency at the Fe centre, in a hitherto unreported excited singlet state that either converts to the triplet ground state or combines with a CO or solvent molecule to regenerate a penta-coordinated Fe species on a sub-picosecond timescale. This finding, which resolves the debate about the relative importance of different spin channels in the photochemistry of Fe(CO)5 (refs 4, 16,17,18,19 and 20), was made possible by the ability of femtosecond X-ray spectroscopy to probe frontier-orbital interactions with atom specificity. We expect the method to be broadly applicable in the chemical sciences, and to complement approaches that probe structural dynamics in ultrafast processes. [ABSTRACT FROM AUTHOR]

Published
2015
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50. Ultrafast Optical and X-ray Measurements of Femtosecond Lattice Dynamics in Photoexcited Bismuth

Author

Fritz, D. M., primary, Adams, B., additional, Blome, C., additional, Bucksbaum, P.H., additional, Cavalieri, A., additional, Engemann, S., additional, Fahy, S., additional, Fuoss, P. H., additional, Gaffney, K. J., additional, Hillyard, P., additional, Hoegen, M. Horn-von, additional, Kammler, M., additional, Kaspar, J., additional, Lindenberg, A. M., additional, Lee, S. H., additional, McFarland, B., additional, Meyer, D., additional, Murray, E., additional, Nicoul, M., additional, Pahl, R., additional, Rudati, J., additional, Siddons, D. P., additional, Sokolowski-Tinten, K., additional, von der Linde, D., additional, Wahlstrand, J. K., additional, Hastings, J. B., additional, and Reis, D.A., additional

Published
2006
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