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    Abstract:
    If matter absorbs a photon of sufficient energy it emits an electron. The question of the duration of the emission process has intrigued scientists for decades. With the advent of attosecond metrology, experiments addressing such ultrashort intervals became possible. While these types of studies require attosecond experimental precision, we present here a novel measurement approach that avoids those experimental difficulties. We instead extract the emission delay from the interference pattern generated as the emitted photoelectron is diffracted by the parent ion's potential. Targeting core electrons in CO, we measured a 2d map of photoelectron emission delays in the molecular frame over a wide range of electron energies. The measured emission times depend drastically on the emission direction and exhibit characteristic changes along the shape resonance of the molecule. Our approach can be routinely extended to other electron orbitals and more complex molecules.
    Keywords:
    Attosecond
    Photon energy
    Interference effects produced by the superposition of the light beams from two independent single-mode lasers have been investigated experimentally. It is found that interference takes place even under conditions in which the light intensities are so low that, with high probability, one photon is absorbed before the next one is emitted by one or the other source. Since the average number of registered photons per trial was only about 10, photon correlation techniques were required to demonstrate the interference. The interpretation of the experiment, and the question whether it demonstrates interference between two photons, are discussed.
    Citations (275)
    It has been considered to be difficult to calculate the energy quantity, which is transfered to photons composing materials from incident photons, by means of present absorption coefficients. The ratio of transfered energy to photons composing water layer from incident photons (effective energy absorption ratio) was calculated theoretically. Consequently, the ratio of total exit energy to total incident energy as a function of thickness of layer was represented a sigmoid curve on semilogarithmic scale, and was saturated to the value of energy emerged from the layer by back scattered photons. It can be able to calculate the effective energy absorption ratio for given photon energy and for given thickness of layer by following equation, which is a function of photon energy and "effective energy absorption ratio coefficients" (k, n), obtained from the graphs. (effective energy absorption ratio) =1-k×E^n (E : primary photon energy [keV])
    Photon energy
    Two-Photon Absorption
    Abstract We report calculated cross sections and asymmetry parameters for photoionization out of the outermost valence orbital 2 b 2 u of C 2 F 4 for photon energies ranging from near‐threshold to 19 eV. We also report asymmetry parameters for photoionization out of the eight outermost orbitals of C 2 F 4 at the He I radiation energy (21.23 eV). The iterative Schwinger variational method at the exact static‐exchange level is used to obtain the continuum photoelectron orbitals. Our calculated results are compared with experimental results available in the literature. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
    Photon energy
    Quantum defect
    Citations (2)
    We report a two-photon interference experiment in which the detected photons have very different properties. The interference is observed even when no effort is made to mask the distinguishing features before the photons are detected. The results can only be explained in terms of indistinguishable two-photon amplitudes.
    Quantum interference
    The goal of attosecond physics is to probe and control matter on its natural time scale, which for electronic motion in atoms, molecules, and solids is measured in attoseconds (= 10−18 sec). Both single attosecond pulses and attosecond pulse trains can be produced. Such pulses have opened new avenues for time-domain studies of multi-electron dynamics in atoms, molecules, and solids on their natural time scale and at dimensions shorter than molecular and even atomic dimensions. They promise a revolution in our microscopic knowledge and understanding of matter. At present the intensities of isolated attosecond pulses are very weak, so that perturbation theory is sufficient to describe the interaction of attosecond pulses with matter. Consequently, they can only be used either to initiate (“pump”) a physical process or to probe a process already under way by other means. Experimental efforts currently aim to increase the intensities of isolated attosecond pulses by orders of magnitude. Intense attosecond pulses will open the regime of nonlinear attosecond physics, in which pump/probe processes with isolated attosecond pulses will become possible and in which the broad bandwidth of isolated few-cycle attosecond pulses will enable significant control over electron motion.
    Attosecond
    Citations (0)
    The goal of 'attosecond dynamic imaging' is to follow electronic and nuclear dynamics in atoms and molecules with attosecond temporal resolution, with the dream of accomplishing this goal for isolated molecules. Attosecond dynamic imaging also includes the idea of combining attosecond temporal and Angstrom-scale spatial resolution that is, making movies of electronic and nuclear dynamics in individual molecules. One can try several approaches to realize this dream, and this tutorial will focus on one such route: the author will describe the main theoretical and experimental ideas that form the basis of using intense infrared (IR) laser fields for attosecond dynamic imaging, with or without the assistance of attosecond XUV pulses.
    Attosecond
    Temporal resolution
    Extreme ultraviolet
    Using Monte Carlo simulation, reconstruction of photon conversions is studied, and the detection efficiency and energy resolution as a function of photon energy are obtained. The dE/dx correction for the electrons from photon conversions and the energy scale for the photons are calibrated with BES II data. An improved Crystal Ball function describes well the energy distribution of the photons. Photon energy resolutions in the range from 2.3 to 3.8MeV are found for the photons with energy from 100 to 260MeV at the BES II detector.
    Photon energy
    Citations (0)