1,721,009 research outputs found
Controlling the angular momentum composition of a Rydberg electron wave packet
No full textSequences of phase-locked laser pulses have been employed to control the orbital angular momentum character of an electron wave packet, which is initially created from a superposition of s and d Rydberg series. By an intelligent choice of phase, which depends on the excitation energy and the quantum defects, we are able to selectively pump down either all or a fraction of one or other angular momentum component, and by employing multichannel quantum-defect theory we are able to analyze the quantum-state distribution in detail
Controlling the radial dynamics of Rydberg wavepackets in Xe using phase-locked optical pulse sequences
No full textWe employ a sequence of two phase-locked optical pulses, separated by half a classical orbit period, to control the radial dynamics of electron wavepackets in Xe. We eliminate either even or odd principal quantum number states from the wavepacket and distinguish between these systems by looking at the wavepacket spectrum at different partial revivals. The experimentally observed dynamics are compared with calculations based on multichannel quantum defect theory and the observations are interpreted in terms of the time and phase evolution of the population amplitudes of the Rydberg states contributing to the wavepacke
Optical control of the rotational angular momentum of a molecular Rydberg wave packet
Full text linkAn intuitive scheme for controlling the rotational quantum state of a Rydberg molecule is demonstrated experimentally. We determine the accumulated phase difference between the various components of a molecular electron wave packet, and then employ a sequence of phase-locked optical pulses to selectively enhance or depopulate specific rotational states. The angular momentum composition of the resulting wave packet, and the efficiency of the control scheme, is determined by calculating the multipulse response of the time-dependent Rydberg populations
Observation and control of dissociating and autoionizing Rydberg electron wave packets in NO
No full textThe dynamics of predissociating Rydberg electron wave packets are observed using the optical Ramsey method. The time-resolved spectra are hydrogenic and are very well modeled by assuming that only one p Rydberg series contributes to the dynamics. This is in contrast with previous observations of autoionizing Rydberg electron wave packets [Phys. Rev. Lett. 83, 2552 (1999)], which show quite dramatic deviations from hydrogenic behavior above the Born–Oppenheimer limit. The origin of these deviations lies in the interplay between electronic and molecular phase. By exploiting these phases we are able to control the ratio of predissociaton to autoionization
Femtosecond spectroscopy of cluster anions: insights into condensed-phase phenomena from the gas-phase
No full textUnraveling the decarboxylation dynamics of the fluorescein dianion with fragment action spectroscopy
Full text linkThe decarboxylation dynamics of the doubly deprotonated fluorescein dianion, Fl2−, are investigated by recording fragment action spectra for the anion, Fl−, and its decarboxylated analog, Fl–CO2−, using a new reflectron secondary mass spectrometer. The formation of the anion, Fl−, is directly investigated by photoelectron imaging. The Fl− and Fl–CO2− action spectra indicate that, for λ 400 nm, decarboxylation only proceeds following electron loss via a sequential two-photon process. The primary decarboxylation pathway is the ready loss of CO2 from the relatively short-lived intermediate excited state, Fl−[D1], which is formed by electron loss from the dianion via resonant tunneling through the repulsive Coloumb barrier associated with a high-lying excited dianion state, Fl2−[S2]
Photoelectron spectroscopy of the model GFP chromophore anion
Full text linkA photoelectron spectroscopy study of the anionic model chromophore of the green fluorescent protein is presented. From the photoelectron spectra taken at 3.496 eV, 4.62 eV, and 6.15 eV the vertical and adiabatic detachment energies are determined to be 2.8 ± 0.1 eV and 2.6 ± 0.2 eV, respectively. The vertical detachment energy is higher than the S1 ← S0 absorption maximum (2.57 eV) and indicates that the S1 state is bound with respect to electron detachment in the Franck–Condon region. The photoelectron spectrum taken at 6.15 eV, together with TD-DFT calculations, are used to assign a number of excited states in the neutral radical that correspond to electron loss from occupied orbitals in the anion. The photoelectron spectrum at 2.58 eV shows evidence for electrons formed by thermionic emission, suggesting that internal conversion is the dominant relaxation pathway following S1 ← S0 excitation
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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