TY - JOUR A1 - Wolf, Thomas J. A. A1 - Holzmeier, Fabian A1 - Wagner, Isabella A1 - Berrah, Nora A1 - Bostedt, Christoph A1 - Bozek, John A1 - Bucksbaum, Phil A1 - Coffee, Ryan A1 - Cryan, James A1 - Farrell, Joe A1 - Feifel, Raimund A1 - Martinez, Todd J. A1 - McFarland, Brian A1 - Mucke, Melanie A1 - Nandi, Saikat A1 - Tarantelli, Francesco A1 - Fischer, Ingo A1 - Gühr, Markus T1 - Observing Femtosecond Fragmentation Using Ultrafast X-ray-Induced Auger Spectra JF - Applied sciences N2 - Molecules often fragment after photoionization in the gas phase. Usually, this process can only be investigated spectroscopically as long as there exists electron correlation between the photofragments. Important parameters, like their kinetic energy after separation, cannot be investigated. We are reporting on a femtosecond time-resolved Auger electron spectroscopy study concerning the photofragmentation dynamics of thymine. We observe the appearance of clearly distinguishable signatures from thymines neutral photofragment isocyanic acid. Furthermore, we observe a time-dependent shift of its spectrum, which we can attribute to the influence of the charged fragment on the Auger electron. This allows us to map our time-dependent dataset onto the fragmentation coordinate. The time dependence of the shift supports efficient transformation of the excess energy gained from photoionization into kinetic energy of the fragments. Our method is broadly applicable to the investigation of photofragmentation processes. KW - ultrafast dynamics KW - Auger electron spectroscopy KW - photofragmentation KW - photochemistry Y1 - 2017 U6 - https://doi.org/10.3390/app7070681 SN - 2076-3417 VL - 7 IS - 7 PB - MDPI CY - Basel ER - TY - JOUR A1 - Kulesza, Alexander Jan A1 - Titov, Evgenii A1 - Daly, Steven A1 - Wlodarczyk, Radoslaw A1 - Megow, Jörg A1 - Saalfrank, Peter A1 - Choi, Chang Min A1 - MacAleese, Luke A1 - Antoine, Rodolphe A1 - Dugourd, Philippe T1 - Excited States of Xanthene Analogues: Photofragmentation and Calculations by CC2 and Time-Dependent Density Functional Theory JF - ChemPhysChem : a European journal of chemical physics and physical chemistry N2 - Action spectroscopy has emerged as an analytical tool to probe excited states in the gas phase. Although comparison of gas-phase absorption properties with quantum-chemical calculations is, in principle, straightforward, popular methods often fail to describe many molecules of interest-such as xanthene analogues. We, therefore, face their nano-and picosecond laser-induced photofragmentation with excited-state computations by using the CC2 method and time-dependent density functional theory (TDDFT). Whereas the extracted absorption maxima agree with CC2 predictions, the TDDFT excitation energies are blueshifted. Lowering the amount of Hartree-Fock exchange in the DFT functional can reduce this shift but at the cost of changing the nature of the excited state. Additional bandwidth observed in the photofragmentation spectra is rationalized in terms of multiphoton processes. Observed fragmentation from higher-lying excited states conforms to intense excited-to-excited state transitions calculated with CC2. The CC2 method is thus suitable for the comparison with photofragmentation in xanthene analogues. KW - density functional calculations KW - CC2 calculations KW - multiphoton processes KW - photofragmentation KW - xanthenes Y1 - 2016 U6 - https://doi.org/10.1002/cphc.201600650 SN - 1439-4235 SN - 1439-7641 VL - 17 SP - 3129 EP - 3138 PB - Wiley-VCH CY - Weinheim ER - TY - GEN A1 - Wolf, Thomas J. A. A1 - Holzmeier, Fabian A1 - Wagner, Isabella A1 - Berrah, Nora A1 - Bostedt, Christoph A1 - Bozek, John A1 - Bucksbaum, Philip H. A1 - Coffee, Ryan A1 - Cryan, James A1 - Farrell, Joe A1 - Feifel, Raimund A1 - Martinez, Todd J. A1 - McFarland, Brian A1 - Mucke, Melanie A1 - Nandi, Saikat A1 - Tarantelli, Francesco A1 - Fischer, Ingo A1 - Gühr, Markus T1 - Observing Femtosecond Fragmentation Using Ultrafast X-ray-Induced Auger Spectra N2 - Molecules often fragment after photoionization in the gas phase. Usually, this process can only be investigated spectroscopically as long as there exists electron correlation between the photofragments. Important parameters, like their kinetic energy after separation, cannot be investigated. We are reporting on a femtosecond time-resolved Auger electron spectroscopy study concerning the photofragmentation dynamics of thymine. We observe the appearance of clearly distinguishable signatures from thymine′s neutral photofragment isocyanic acid. Furthermore, we observe a time-dependent shift of its spectrum, which we can attribute to the influence of the charged fragment on the Auger electron. This allows us to map our time-dependent dataset onto the fragmentation coordinate. The time dependence of the shift supports efficient transformation of the excess energy gained from photoionization into kinetic energy of the fragments. Our method is broadly applicable to the investigation of photofragmentation processes. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 386 KW - Auger electron spectroscopy KW - photochemistry KW - photofragmentation KW - ultrafast dynamics Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-402692 ER - TY - JOUR A1 - Wolf, Thomas J. A. A1 - Holzmeier, Fabian A1 - Wagner, Isabella A1 - Berrah, Nora A1 - Bostedt, Christoph A1 - Bozek, John A1 - Bucksbaum, Philip H. A1 - Coffee, Ryan A1 - Cryan, James A1 - Farrell, Joe A1 - Feifel, Raimund A1 - Martinez, Todd J. A1 - McFarland, Brian A1 - Mucke, Melanie A1 - Nandi, Saikat A1 - Tarantelli, Francesco A1 - Fischer, Ingo A1 - Gühr, Markus T1 - Observing Femtosecond Fragmentation Using Ultrafast X-ray-Induced Auger Spectra JF - Applied Sciences N2 - Molecules often fragment after photoionization in the gas phase. Usually, this process can only be investigated spectroscopically as long as there exists electron correlation between the photofragments. Important parameters, like their kinetic energy after separation, cannot be investigated. We are reporting on a femtosecond time-resolved Auger electron spectroscopy study concerning the photofragmentation dynamics of thymine. We observe the appearance of clearly distinguishable signatures from thymine′s neutral photofragment isocyanic acid. Furthermore, we observe a time-dependent shift of its spectrum, which we can attribute to the influence of the charged fragment on the Auger electron. This allows us to map our time-dependent dataset onto the fragmentation coordinate. The time dependence of the shift supports efficient transformation of the excess energy gained from photoionization into kinetic energy of the fragments. Our method is broadly applicable to the investigation of photofragmentation processes. KW - ultrafast dynamics KW - Auger electron spectroscopy KW - photofragmentation KW - photochemistry Y1 - 2017 U6 - https://doi.org/10.3390/app7070681 SN - 2076-3417 VL - 7 IS - 7 PB - MDPI CY - Basel ER -