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Your search keyword '"Prince, K. C."' showing total 10 results
Start Over Author "Prince, K. C." Publisher uppsala universitet, molekyl- och kondenserade materiens fysik
10 results on '"Prince, K. C."'

1. Acetylacetone photodynamics at a seeded free-electron laser

Author

Squibb, R. J., Sapunar, M., Ponzi, A., Richter, R., Kivimaki, A., Plekan, O., Finetti, P., Sisourat, N., Zhaunerchyk, V., Marchenko, T., Journel, L., Guillemin, R., Cucini, R., Coreno, M., Grazioli, C., Di Fraia, M., Callegari, C., Prince, K. C., Decleva, P., Simon, M., Eland, J. H. D., Doslic, N., Feifel, R., Piancastelli, Maria Novella, Squibb, R. J., Sapunar, M., Ponzi, A., Richter, R., Kivimaki, A., Plekan, O., Finetti, P., Sisourat, N., Zhaunerchyk, V., Marchenko, T., Journel, L., Guillemin, R., Cucini, R., Coreno, M., Grazioli, C., Di Fraia, M., Callegari, C., Prince, K. C., Decleva, P., Simon, M., Eland, J. H. D., Doslic, N., Feifel, R., and Piancastelli, Maria Novella

Abstract

The first steps in photochemical processes, such as photosynthesis or animal vision, involve changes in electronic and geometric structure on extremely short time scales. Time-resolved photoelectron spectroscopy is a natural way to measure such changes, but has been hindered hitherto by limitations of available pulsed light sources in the vacuum-ultraviolet and soft Xray spectral region, which have insufficient resolution in time and energy simultaneously. The unique combination of intensity, energy resolution, and femtosecond pulse duration of the FERMI-seeded free-electron laser can now provide exceptionally detailed information on photoexcitation-deexcitation and fragmentation in pump-probe experiments on the 50-femtosecond time scale. For the prototypical system acetylacetone we report here electron spectra measured as a function of time delay with enough spectral and time resolution to follow several photoexcited species through well-characterized individual steps, interpreted using state-of-the-art static and dynamics calculations. These results open the way for investigations of photochemical processes in unprecedented detail.

Published
2018
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2. Covariance mapping of two-photon double core hole states in C2H2 and C2H6 produced by an x-ray free electron laser

Author

Mucke, Melanie, Zhaunerchyk, Vitali, Frasinski, L. J., Squibb, Richard J., Siano, M., Eland, John H. D., Linusson, P., Salen, P., v d Meulen, P., Thomas, R. D., Larsson, M., Foucar, L., Ullrich, J., Motomura, K., Mondal, S., Ueda, K., Osipov, T., Fang, L., Murphy, B. F., Berrah, N., Bostedt, C., Bozek, J. D., Schorb, S., Messerschmidt, M., Glownia, J. M., Cryan, J. P., Coffee, R. N., Takahashi, O., Wada, S., Piancastelli, Maria Novella, Richter, R., Prince, K. C., Feifel, Raimund, Mucke, Melanie, Zhaunerchyk, Vitali, Frasinski, L. J., Squibb, Richard J., Siano, M., Eland, John H. D., Linusson, P., Salen, P., v d Meulen, P., Thomas, R. D., Larsson, M., Foucar, L., Ullrich, J., Motomura, K., Mondal, S., Ueda, K., Osipov, T., Fang, L., Murphy, B. F., Berrah, N., Bostedt, C., Bozek, J. D., Schorb, S., Messerschmidt, M., Glownia, J. M., Cryan, J. P., Coffee, R. N., Takahashi, O., Wada, S., Piancastelli, Maria Novella, Richter, R., Prince, K. C., and Feifel, Raimund

Abstract

Few-photon ionization and relaxation processes in acetylene (C2H2) and ethane (C2H6) were investigated at the linac coherent light source x-ray free electron laser (FEL) at SLAC, Stanford using a highly efficient multi-particle correlation spectroscopy technique based on a magnetic bottle. The analysis method of covariance mapping has been applied and enhanced, allowing us to identify electron pairs associated with double core hole (DCH) production and competing multiple ionization processes including Auger decay sequences. The experimental technique and the analysis procedure are discussed in the light of earlier investigations of DCH studies carried out at the same FEL and at third generation synchrotron radiation sources. In particular, we demonstrate the capability of the covariance mapping technique to disentangle the formation of molecular DCH states which is barely feasible with conventional electron spectroscopy methods.

Published
2015
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3. A study of the dynamical energy flow in uracil

Author

Bolognesi, P., O'Keeffe, P., Mazza, T., Bozek, J., Coffee, R., Bostedt, C., Schorb, S., Carron, S., Feifel, Raimund, Mucke, Melanie, Guehr, M., Sistrunk, E. F., Grilj, J., McFarland, B. K., Koch, M., Larsson, M., Salem, P., Berrah, N., Fang, L., Osipov, T., Murphy, B., Lucchese, R. R., Meyer, M., Piancastelli, Maria Novella, Ueda, K., Mondal, S., Miron, C., Richter, R., Prince, K. C., Takahashi, O., Avaldi, L., Bolognesi, P., O'Keeffe, P., Mazza, T., Bozek, J., Coffee, R., Bostedt, C., Schorb, S., Carron, S., Feifel, Raimund, Mucke, Melanie, Guehr, M., Sistrunk, E. F., Grilj, J., McFarland, B. K., Koch, M., Larsson, M., Salem, P., Berrah, N., Fang, L., Osipov, T., Murphy, B., Lucchese, R. R., Meyer, M., Piancastelli, Maria Novella, Ueda, K., Mondal, S., Miron, C., Richter, R., Prince, K. C., Takahashi, O., and Avaldi, L.

Abstract

The time resolved photoionization of C 1s in uracil following excitation of the neutral molecule by 260 nm pulses has been studied at LCLS.

Published
2015
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4. Disentangling formation of multiple-core holes in aminophenol molecules exposed to bright X-FEL radiation

Author

Zhaunerchyk, Vitali, Kaminska, Magdalena, Mucke, Melanie, Squibb, R. J., Eland, John H. D., Piancastelli, Maria Novella, Frasinski, L. J., Grilj, J., Koch, M., McFarland, B. K., Sistrunk, E., Guehr, M., Coffee, R. N., Bostedt, C., Bozek, J. D., Salen, P., Meulen, P. V. D., Linusson, P., Thomas, R. D., Larsson, M., Foucar, L., Ullrich, J., Motomura, K., Mondal, S., Ueda, K., Richter, R., Prince, K. C., Takahashi, O., Osipov, T., Fang, L., Murphy, B. F., Berrah, N., Feifel, Raimund, Zhaunerchyk, Vitali, Kaminska, Magdalena, Mucke, Melanie, Squibb, R. J., Eland, John H. D., Piancastelli, Maria Novella, Frasinski, L. J., Grilj, J., Koch, M., McFarland, B. K., Sistrunk, E., Guehr, M., Coffee, R. N., Bostedt, C., Bozek, J. D., Salen, P., Meulen, P. V. D., Linusson, P., Thomas, R. D., Larsson, M., Foucar, L., Ullrich, J., Motomura, K., Mondal, S., Ueda, K., Richter, R., Prince, K. C., Takahashi, O., Osipov, T., Fang, L., Murphy, B. F., Berrah, N., and Feifel, Raimund

Abstract

Competing multi-photon ionization processes, some leading to the formation of double core hole states, have been examined in 4-aminophenol. The experiments used the linac coherent light source (LCLS) x-ray free electron laser, in combination with a time-of-flight magnetic bottle electron spectrometer and the correlation analysis method of covariance mapping. The results imply that 4-aminophenol molecules exposed to the focused x-ray pulses of the LCLS sequentially absorb more than two x-ray photons, resulting in the formation of multiple core holes as well as in the sequential removal of photoelectrons and Auger electrons (so-called PAPA sequences).

Published
2015
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5. High resolution multiphoton spectroscopy by a tunable free-electron-laser light

Author

Zitnik, M, Mihelič, A, Bučar, K, Kavčič, M, Rubensson, Jan-Erik, Svanqvist, Mattias, Söderström, Johan, Feifel, Raimund, Såthe, C, Ovcharenko, Y, Lyamayev, V, Mazza, T, Meyer, M, Simon, M, Journel, L, Lüning, J, Plekan, O, Coreno, M, Devetta, M, Di Fraia, M, Finetti, P, Richter, R, Grazioli, C, Prince, K C, Callegari, C, Zitnik, M, Mihelič, A, Bučar, K, Kavčič, M, Rubensson, Jan-Erik, Svanqvist, Mattias, Söderström, Johan, Feifel, Raimund, Såthe, C, Ovcharenko, Y, Lyamayev, V, Mazza, T, Meyer, M, Simon, M, Journel, L, Lüning, J, Plekan, O, Coreno, M, Devetta, M, Di Fraia, M, Finetti, P, Richter, R, Grazioli, C, Prince, K C, and Callegari, C

Abstract

Seeded free electron lasers theoretically have the intensity, tunability, and resolution required for multiphoton spectroscopy of atomic and molecular species. Using the seeded free electron laser FERMI and a novel detection scheme, we have revealed the two-photon excitation spectra of dipole-forbidden doubly excited states in helium. The spectral profiles of the lowest (-1,0)^{+1} ^{1}S^{e} and (0,1)^{0} ^{1}D^{e} resonances display energy shifts in the meV range that depend on the pulse intensity. The results are explained by an effective two-level model based on calculated Rabi frequencies and decay rates.

Published
2014
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6. Double core-hole formation in small molecules at the LCLS free electron laser

Author

Larsson, M., Salen, P., van der Meulen, P., Schmidt, H. T., Thomas, R. D., Feifel, Raimund, Piancastelli, Maria Novella, Fang, L., Murphy, B. F., Osipov, T., Berrah, N., Kukk, E., Ueda, K., Bozek, J. D., Bostedt, C., Wada, S., Richter, R., Feyer, V., Prince, K. C., Larsson, M., Salen, P., van der Meulen, P., Schmidt, H. T., Thomas, R. D., Feifel, Raimund, Piancastelli, Maria Novella, Fang, L., Murphy, B. F., Osipov, T., Berrah, N., Kukk, E., Ueda, K., Bozek, J. D., Bostedt, C., Wada, S., Richter, R., Feyer, V., and Prince, K. C.

Abstract

We have investigated nonlinear processes in small molecules by x-ray photoelectron spectroscopy using the Linac Coherent Light Source free electron laser, and by simulations. The main focus of the experiments was the formation of the two-site double core-hole (tsDCH) states in the molecules CO2, N2O and N-2. These experiments are described in detail and the results are compared with simulations of the photoelectron spectra. The double core-hole states, and in particular the tsDCH states, have been predicted to be highly sensitive to the chemical environment. The theory behind this chemical sensitivity is validated by the experiments. Furthermore, our simulations of the relative integrated intensities of the peaks associated with the nonlinear processes show that this type of simulation, in combination with experimental data, provides a useful tool for estimating the duration of ultra-short x-ray pulses.

Published
2013
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7. Using covariance mapping to investigate the dynamics of multi-photon ionization processes of Ne atoms exposed to X-FEL pulses

Author

Zhaunerchyk, Vitali, Mucke, Melanie, Salen, P., vd Meulen, P., Kaminska, Magdalena, Squibb, Richard J., Frasinski, L. J., Siano, M., Eland, John H. D., Linusson, P., Thomas, R. D., Larsson, M., Foucar, L., Ullrich, J., Motomura, K., Mondal, S., Ueda, K., Osipov, T., Fang, L., Murphy, B. F., Berrah, N., Bostedt, C., Bozek, J. D., Schorb, S., Messerschmidt, M., Glownia, J. M., Cryan, J. P., Coffee, R. N., Takahashi, O., Wada, S., Piancastelli, Maria Novella, Richter, R., Prince, K. C., Feifel, Raimund, Zhaunerchyk, Vitali, Mucke, Melanie, Salen, P., vd Meulen, P., Kaminska, Magdalena, Squibb, Richard J., Frasinski, L. J., Siano, M., Eland, John H. D., Linusson, P., Thomas, R. D., Larsson, M., Foucar, L., Ullrich, J., Motomura, K., Mondal, S., Ueda, K., Osipov, T., Fang, L., Murphy, B. F., Berrah, N., Bostedt, C., Bozek, J. D., Schorb, S., Messerschmidt, M., Glownia, J. M., Cryan, J. P., Coffee, R. N., Takahashi, O., Wada, S., Piancastelli, Maria Novella, Richter, R., Prince, K. C., and Feifel, Raimund

Abstract

We report on a detailed investigation into the electron emission processes of Ne atoms exposed to intense femtosecond x-ray pulses, provided by the Linac Coherent Light Source Free Electron Laser (FEL) at Stanford. The covariance mapping technique is applied to analyse the data, and the capability of this approach to disentangle both linear and nonlinear correlation features which may be hidden on coincidence maps of the same data set is demonstrated. Different correction techniques which enable improvements on the quality of the spectral features extracted from the covariance maps are explored. Finally, a method for deriving characteristics of the x-ray FEL pulses based on covariance mapping in combination with model simulations is presented.

Published
2013
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8. Dynamics of Hollow Atom Formation in Intense X-Ray Pulses Probed by Partial Covariance Mapping

Author

Frasinski, L. J., Zhaunerchyk, Vitali, Mucke, Melanie, Squibb, Richard J., Siano, M., Eland, John H. D., Linusson, P., v. d. Meulen, P., Salen, P., Thomas, R. D., Larsson, M., Foucar, L., Ullrich, J., Motomura, K., Mondal, S., Ueda, K., Osipov, T., Fang, L., Murphy, B. F., Berrah, N., Bostedt, C., Bozek, J. D., Schorb, S., Messerschmidt, M., Glownia, J. M., Cryan, J. P., Coffee, R. N., Takahashi, O., Wada, S., Piancastelli, Maria Novella, Richter, R., Prince, K. C., Feifel, Raimund, Frasinski, L. J., Zhaunerchyk, Vitali, Mucke, Melanie, Squibb, Richard J., Siano, M., Eland, John H. D., Linusson, P., v. d. Meulen, P., Salen, P., Thomas, R. D., Larsson, M., Foucar, L., Ullrich, J., Motomura, K., Mondal, S., Ueda, K., Osipov, T., Fang, L., Murphy, B. F., Berrah, N., Bostedt, C., Bozek, J. D., Schorb, S., Messerschmidt, M., Glownia, J. M., Cryan, J. P., Coffee, R. N., Takahashi, O., Wada, S., Piancastelli, Maria Novella, Richter, R., Prince, K. C., and Feifel, Raimund

Abstract

When exposed to ultraintense x-radiation sources such as free electron lasers (FELs) the innermost electronic shell can efficiently be emptied, creating a transient hollow atom or molecule. Understanding the femtosecond dynamics of such systems is fundamental to achieving atomic resolution in flash diffraction imaging of noncrystallized complex biological samples. We demonstrate the capacity of a correlation method called "partial covariance mapping'' to probe the electron dynamics of neon atoms exposed to intense 8 fs pulses of 1062 eV photons. A complete picture of ionization processes competing in hollow atom formation and decay is visualized with unprecedented ease and the map reveals hitherto unobserved nonlinear sequences of photoionization and Auger events. The technique is particularly well suited to the high counting rate inherent in FEL experiments.

Published
2013
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9. Angular effects in autoionization of 3 P doubly excited states in He

Author

Alagia, M, Coreno, M, Farrokhpour, H, Franceschi, P, Mihelič, A, Moise, A, Omidyan, R, Prince, K C, Richter, R, Söderström, Johan, Stranges, S, Tabrizchi, M, Åœitnik, M, Alagia, M, Coreno, M, Farrokhpour, H, Franceschi, P, Mihelič, A, Moise, A, Omidyan, R, Prince, K C, Richter, R, Söderström, Johan, Stranges, S, Tabrizchi, M, and Åœitnik, M

Abstract

The first members of dipole allowed 3 P o doubly excited series in helium have been observed in resonant photoexcitation of 1 s 2 s 3 S e metastable atoms. A good agreement measured relative photoionization cross sections is achieved when theory includes the radiation damping and, also important, the effects of spin-orbit multiplet splitting on electron angular distribution.

Published
2009

10. High resolution multiphoton spectroscopy by a tunable free-electron-laser light

Author

Carlo Callegari, Cesare Grazioli, Paola Finetti, Conny Såthe, Marcello Coreno, Kevin C. Prince, Jan-Erik Rubensson, Jan Lüning, Tommaso Mazza, Johan Söderström, Robert Richter, Moritz Meyer, Raimund Feifel, A. Mihelič, M. Devetta, Klemen Bučar, V. Lyamayev, Y. Ovcharenko, Matjaž Kavčič, Marc Simon, Oksana Plekan, M. Di Fraia, M. Svanquist, M. Žitnik, L. Journel, Žitnik, M., Mihelič, A., Bučar, K., Kavčič, M., Rubensson, J. E., Svanquist, M., Söderström, J., Feifel, R., Såthe, C., Ovcharenko, Y., Lyamayev, V., Mazza, T., Meyer, M., Simon, M., Journel, L., Lüning, J., Plekan, O., Coreno, M., Devetta, M., DI FRAIA, Michele, Finetti, P., Richter, R., Grazioli, C., Prince, K. . C., and Callegari, C.

Subjects
Free electron model, FEL, spectroscopy, Materials science, Resolution (electron density), Free-electron laser, General Physics and Astronomy, chemistry.chemical_element, helium, Laser, law.invention, chemistry, law, Excited state, Physical Sciences, ddc:550, Fysik, Physics::Atomic Physics, Atomic physics, Spectroscopy, Helium, Energy (signal processing)
Abstract

Seeded free electron lasers theoretically have the intensity, tunability, and resolution required for multiphoton spectroscopy of atomic and molecular species. Using the seeded free electron laser FERMI and a novel detection scheme, we have revealed the two-photon excitation spectra of dipole-forbidden doubly excited states in helium. The spectral profiles of the lowest (-1,0)^{+1} ^{1}S^{e} and (0,1)^{0} ^{1}D^{e} resonances display energy shifts in the meV range that depend on the pulse intensity. The results are explained by an effective two-level model based on calculated Rabi frequencies and decay rates.

Published
2014
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