Magnetic Bottle Electron Spectrometer Research Articles

Dissociation following the Auger decay of xenon difluoride molecules.

This study investigated the dissociation after the Xe 4d Auger decay of weak-bonding XeF2 molecules by multielectron-ion coincidence spectroscopy using a magnetic bottle electron spectrometer. Fragmentations from the XeF22+ states were clarified in the Auger spectra coincident with individual ion species. It was observed that the two-hole population led by the Auger decay was not directly inherited during the fragmentation of XeF22+. Furthermore, the dissociations of XeF23+ states produced by the double Auger decay were investigated.

Metastability and fragmentation of the OCS3+ states produced by S 2p double Auger decay.

The metastability and the dissociation processes of the OCS3+ states produced by the S 2p double Auger decay of OCS are investigated by multi-electron-ion coincidence spectroscopy using a magnetic bottle electron spectrometer. The spectra of the OCS3+ states filtered for the production of individual ions are derived by four-fold (or five-fold) coincidence among three electrons and a product ion (or two ions). The ground OCS3+ state is confirmed to be metastable in the 10 µs regime. The OCS3+ states relevant to the individual channels of two- and three-body dissociations are clarified.

Sequential quadruple Auger decay pathways from the Xe 4s core-hole state

The sequential quadruple Auger decay of the Xe $4s$ core-hole state has been investigated by multielectron-ion coincidence spectroscopy using a magnetic bottle electron spectrometer. The high collection efficiency for electrons and ions enables sixfold coincidence measurement of all the emitted electrons and the product ${\mathrm{Xe}}^{5+}$ ion. While the Auger electrons emitted in the different Auger steps greatly overlap each other in energy, step-by-step analysis of the energy correlation among Auger electrons in coincidence discloses two important quadruple Auger decay pathways.

Resonant two-photon ionization of helium atoms studied by attosecond interferometry

We study resonant two-photon ionization of helium atoms via the 1s3p, 1s4p and 1s5p1P1 states using the 15th harmonic of a titanium-sapphire laser for the excitation and a weak fraction of the laser field for the ionization. The phase of the photoelectron wavepackets is measured by an attosecond interferometric technique, using the 17th harmonic. We perform experiments with angular resolution using a velocity map imaging spectrometer and with high energy resolution using a magnetic bottle electron spectrometer. Our results are compared to calculations using the two-photon random phase approximation with exchange to account for electron correlation effects. We give an interpretation for the multiple π-rad phase jumps observed, both at and away from resonance, as well as their dependence on the emission angle.

Construction of a Magnetic Bottle Electron Spectrometer for Electron Energy Measurement in BISER X-Rays and Xe Interaction

Construction of a Magnetic Bottle Electron Spectrometer for Electron Energy Measurement in BISER X-Rays and Xe Interaction

Multi-electron–ion coincidence spectrometer with a high-efficiency microchannel plate detector

A microchannel plate detector with a large open area ratio (nominally 90%) has been installed in a magnetic bottle electron spectrometer in order to improve the coincidence efficiency in multi-electron−ion coincidence measurements. The overall detection efficiency of the magnetic bottle spectrometer is determined to be ~70% for electrons with kinetic energies of up to at least 530 eV and ~85% for XeZ+ (Z > 3) ions. The usefulness of the improved detection efficiency in multi-electron−ion coincidence spectroscopy is demonstrated by a six-fold coincidence measurement about the quadruple Auger decay of the Xe 3d5/2 core-hole state.

A modified magnetic bottle electron spectrometer for the detection of multiply charged ions in coincidence with all correlated electrons: decay pathways to Xe3+ above xenon-4d ionization threshold

New magnet design of a magnetic bottle electron spectrometer allowing the detection of multiply charged ions in coincidence with n electrons. Electrons spectra obtained without and with filtering by coincidence with Xen+ ions.

A multipurpose end-station for atomic, molecular and optical sciences and coherent diffractive imaging at ELI beamlines

We report on the status of a users’ end-station, MAC: a Multipurpose station for Atomic, molecular and optical sciences and Coherent diffractive imaging, designed for studies of structure and dynamics of matter in the femtosecond time-domain. MAC is located in the E1 experimental hall on the high harmonic generation (HHG) beamline of the ELI Beamlines facility. The extreme ultraviolet beam from the HHG beamline can be used at the MAC end-station together with a synchronized pump beam (which will cover the NIR/Vis/UV or THz range) for time-resolved experiments on different samples. Sample delivery systems at the MAC end-station include a molecular beam, a source for pure or doped clusters, ultrathin cylindrical or flat liquid jets, and focused beams of substrate-free nanoparticles produced by an electrospray or a gas dynamic virtual nozzle combined with an aerodynamic lens stack. We further present the available detectors: electron/ion time-of-flight and velocity map imaging spectrometers and an X-ray camera, and discuss future upgrades: a magnetic bottle electron spectrometer, production of doped nanodroplets and the planned developments of beam capabilities at the MAC end-station.

Design and characterization of a magnetic bottle electron spectrometer for time-resolved extreme UV and X-ray photoemission spectroscopy of liquid microjets

We describe a magnetic bottle time-of-flight electron spectrometer designed for time-resolved photoemission spectroscopy of a liquid microjet using extreme UV and X-ray radiation. The spectrometer can be easily reconfigured depending on experimental requirements and the energy range of interest. To improve the energy resolution at high electron kinetic energy, a retarding potential can be applied either via a stack of electrodes or retarding mesh grids, and a flight-tube extension can be attached to increase the flight time. A gated electron detector was developed to reject intense parasitic signal from light scattered off the surface of the cylindrically shaped liquid microjet. This detector features a two-stage multiplication with a microchannel plate plus a fast-response scintillator followed by an image-intensified photon detector. The performance of the spectrometer was tested at SPring-8 and SACLA, and time-resolved photoelectron spectra were measured for an ultrafast charge transfer to solvent reaction in an aqueous NaI solution with a 200 nm UV pump pulses from a table-top ultrafast laser and the 5.5 keV hard X-ray probe pulses from SACLA.

URSA-PQ: A Mobile and Flexible Pump-Probe Instrument for Gas Phase Samples at the FLASH Free Electron Laser

We present a highly flexible and portable instrument to perform pump-probe spectroscopy with an optical and an X-ray pulse in the gas phase. The so-called URSA-PQ (German for ‘Ultraschnelle Röntgenspektroskopie zur Abfrage der Photoenergiekonversion an Quantensystemen’, Engl. ‘ultrafast X-ray spectroscopy for probing photoenergy conversion in quantum systems’) instrument is equipped with a magnetic bottle electron spectrometer (MBES) and tools to characterize the spatial and temporal overlap of optical and X-ray laser pulses. Its adherence to the CAMP instrument dimensions allows for a wide range of sample sources as well as other spectrometers to be included in the setup. We present the main design and technical features of the instrument. The MBES performance was evaluated using Kr M4,5NN Auger lines using backfilled Kr gas, with an energy resolution ΔE/E ≅ 1/40 in the integrating operative mode. The time resolution of the setup at FLASH 2 FL 24 has been characterized with the help of an experiment on 2-thiouracil that is inserted via the instruments’ capillary oven. We find a time resolution of 190 fs using the molecular 2p photoline shift and attribute this to different origins in the UV-pump—the X-ray probe setup.

Magnetic bottle electron spectrometer driven by electron pulses.

We report an electron scattering experiment on argon gas where a keV electron beam is used as a probe and electrons are collected with a magnetic bottle spectrometer. For this purpose, we have built a thermionic gun that produces electron pulses with nanosecond duration by sweeping the beam across a small aperture. To reach the target, electrons must pass through the hole in an axially symmetric arrangement of strong permanent magnets required to operate the magnetic bottle. From the recorded multi-hit sequence of electron arrival times on the microchannel plate detector, a kinetic energy spectrum is built that allows an analysis of the elastic and inelastic electron scattering channels by means of the coincidence technique. After a description of the instrumental configuration and discussion of suitable working parameters, the results of an angle-integrated (e, 2e) experiment are presented for 800 eV electron scattering on argon atoms.

A virtual stretch of light pulse interval by pulsed electron extraction introduced into a magnetic bottle electron spectrometer.

A pulsed extraction of electrons associated with a single light pulse is introduced into electron time-of-flight measurement by using a magnetic bottle electron spectrometer. The pulsed extraction enables us to observe long times-of-flight of electrons with synchrotron radiation pulses of short periods. The feasibility and the performance of this method are demonstrated by multielectron coincidence measurements for Xe 4d excitation/ionization.

Electron emission relevant to inner-shell photoionization of condensed water studied by multi-electron coincidence spectroscopy

Multi-electron coincidence spectroscopy using a magnetic-bottle electron spectrometer has been applied to the study of the Auger decay following O1s photoionization of condensed H2O molecules. Coincidence Auger spectra are obtained for three different photoelectron energy ranges. In addition, the energy distribution of the slow electrons ejected in the Auger decay of the O1s core hole is deduced from three-fold coincidences.

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

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).

High resolution electron spectrometers for characterizing the contrast of isolated 25 as pulses

We quantify the effects of the energy resolution of a magnetic bottle electron spectrometer in an attosecond streak camera on the accuracy of measuring the relative amplitudes of satellite pulses around the main attosecond pulse. Our numerical simulations show that the spectral resolution can be significantly improved by restricting the acceptance angle using a pinhole located near the source of the photoelectrons. The intensity of the pre- and post-pulses which are 1% and 10% of a main 25 as pulse can potentially be measured with less than 10% error by two practical time-of-flight spectrometer designs.

Multi-electron coincidence spectroscopy: double photoionization from molecular inner-shell orbitals

We have studied double photoionization from molecular inner-shell orbitals and investigated the properties of the resultant double core-hole states in molecules, by multi-electron coincidence spectroscopy with a magnetic bottle electron spectrometer. A brief summary of our previous studies is presented.

A high-resolution magnetic bottle electron spectrometer and its application to a photoelectron–Auger electron coincidence measurement of the L2,3VV Auger decay in CS2

The energy resolution and the detection efficiency of a magnetic bottle electron spectrometer equipped with an electrostatic retarder are examined, with a particular focus on its application to electron coincidence measurements. The electrostatic retardation properly improves the energy resolving power of the spectrometer. No significant decrease in detection efficiency is observed when retardation voltages are applied. Photoelectron–Auger electron coincidence measurement of the L2,3VV Auger decay in CS2 is performed by using the magnetic bottle spectrometer, which reveals Auger transition intensities varying for the different core holes.

Site-specific Auger electron spectra of ethyl trifluoroacelate molecules studied by magnetic bottle electron spectrometer

We performed multielectron coincidence measurements for inner-shell photoionizations of ethyl trifluoroacelate molecules (C4H5F3O2) using a magnetic bottle electron spectrometer. From a two dimensional coincidence map between a photoelectron and Auger electron for C 1s ionizations, we extracted site-specific Auger electron spectra for each carbon site and corresponding binding energy of doubly charged states.

A magnetic-bottle multi-electron-ion coincidence spectrometer

A novel multi-electron-ion coincidence spectrometer developed on the basis of a 1.5 m-long magnetic-bottle electron spectrometer is presented. Electrons are guided by an inhomogeneous magnetic field to a detector at the end of the flight tube, while a set of optics is used to extract counterpart ions to the same detector, by a pulsed inhomogeneous electric field. This setup allows ion detection with high mass resolution, without impairing the high collection efficiency for electrons. The performance of the coincidence spectrometer was tested with double ionization of carbon disulfide, CS(2) → CS(2)(2+) + e(-) + e(-), in ultrashort intense laser fields (2.8 × 10(13) W/cm(2), 280 fs, 1030 nm) to clarify the electron correlation below the rescattering threshold.

Photoelectron spectroscopy ofO−at 266 nm: Ratio of ground- and excited-state atomic oxygen production and channel-resolved photoelectron anisotropy parameters

The photodetachment dynamics of the atomic oxygen anion ${\mathrm{O}}^{\ensuremath{-}}$ has been investigated at 266 nm (4.67 eV) by photoelectron detection in a crossed-beam experiment using a magnetic-bottle electron spectrometer. Taking explicit advantage of the Doppler shift imposed by the moving ion beam on the photoelectron energies, we report both the final-state branching ratio and photoelectron angular distributions. After photoabsorption at 266 nm, the formed electron-oxygen scattering state disintegrates, forming either the excited ${}^{1}D$ or the ground ${}^{3}P$ state of oxygen with a partition of ${}^{1}D$:${}^{3}P=0.32$ $\ifmmode\pm\else\textpm\fi{}$ 0.06. The detachment leading to the production of O(${}^{3}P$) shows an angular distribution of photoelectrons characterized by ${\ensuremath{\beta}}_{P}=0.00$ $\ifmmode\pm\else\textpm\fi{}$ 0.10 mimicking a pure s-wave detachment, while the detachment into excited O(${}^{1}D$) occurs with ${\ensuremath{\beta}}_{D}=\ensuremath{-}0.90\ifmmode\pm\else\textpm\fi{}0.10$, giving direct evidence of interference between the outgoing $s$ and $d$ waves.