Anisotropy parameters and cross section ratios of two-color two-photon above threshold ionization sidebands from argon are measured using photoelectron velocity map imaging with the selected 13th or 15th high-order harmonics in a perturbative 800 nm dressing field. A new data analysis technique determines accurate ...
PubMed
Photoelectron energy spectra for ionization in a strong laser field are calculated within the Floquet framework, for a one-electron model of argon and for other model potentials. The results indicate that, at least for linear polarization and not too short pulse durations, the plateau enhancements dominating high-order above-threshold ...
NASA Astrophysics Data System (ADS)
Energy-dependent photoelectron angular distributions from two-color two-photon above threshold ionizations are investigated to determine the partial-wave characteristics of free-free electronic transitions in helium. Sideband photoelectron energies ranging from 0.18 to 13.0 eV are measured with ...
Many nonlinear quantum phenomena of intense laser-atom physics can be intuitively explained with the concept of trajectory. In this paper, Bohmian mechanics (BM) is introduced to study a multiphoton process of atoms interacting with the intense laser field: above-threshold ionization (ATI). Quantum trajectory of an atomic electron in intense laser field is ...
E-print Network
frequency l. Immediately after being released from the atom in the ionization event, the electron wave above-threshold ionization photoelectron peaks in the strong-field (800 nm, 60 fs, 3.6 - 9.0 � 1013 W model based on calculated field ionization rates in an intense laser field. Finally, the ...
We explore the effects of multiple participating final ion states during strong field ionization (SFI) and high-harmonic generation (HHG) using a two-electron two-center reduced-dimensionality model. In particular, we propose to use above threshold ionization (ATI) photoelectron spectra to ...
Above-threshold ionization of atoms by XUV short laser pulses with frequencies close to the resonant 1s�2p transition is investigated. We present a theory based on a variational expression using trial wavefunctions for the final and the initial states. For the former we use a Coulomb�Volkov wavefunction, and for the latter a close-coupling solution of ...
Photoabsorption above the threshold ionization potential was observed for the photoelectron spectra of CO2 at relatively low laser intensity when resonant with several bound Rydberg states at the three-photon level. It is suggested that these results can be explained in terms of a resonance-enhanced above-threshold absorption (REATA) ...
We investigate high-order above-threshold ionization (HATI) of diatomic molecules having different symmetries by an elliptically polarized laser field using the modified molecular strong-field approximation. The yields of high-energy electrons contributing to the plateau region of the photoelectron spectra strongly depend on the ...
The large polycyclic aromatic hydrocarbon molecules coronene, benzo[GHI]perylene, and anthracene have been ionized with femtosecond laser pulses at low laser intensities and the ionization process studied with velocity map imaging spectroscopy, supplemented with ion yield measurements. The electron spectra of coronene and benzo[GHI]perylene are ...
We present energy-resolved angular distributions of photoelectrons generated in above-threshold ionization (ATI) of nonaligned diatomic molecules N2 and O2 in high-intensity short laser pulses, with emphasis on the most energetic part of the spectra. The angular distribution for photoelectrons with energy of 10U(p) (U(p): ponderomotive ...
We describe the results of experiments performed in Krypton to observe the effect of an isolated atomic level on harmonic generation at intensities above 10{sup 13} W/cm{sup 2}. We have measured the intensity of harmonics produced as a function of laser intensity and focal conditions as well as recorded the photoelectron energy spectra in complementary experiments. We discuss ...
Energy Citations Database
The very pronounced intensity-dependent enhancements of groups of peaks of high-order above-threshold-ionization spectra of rare-gas atoms are investigated using an improved version of the strong-field approximation, which realistically models the respective atom. Two types of enhancements are found and explained in terms of constructive interference of the contributions of a ...
We present the results of a set of quantal and classical calculations designed for simulating the photoelectron spectra observed when atoms are submitted to an intense laser field. We have concentrated the discussion on the range of parameters where conspicuous enhancements are observed in the high-energy part of the above-threshold ionization (ATI) ...
With the help of a suitably chosen momentum-space analysis, we study some of the basic mechanisms governing the physics of the processes occurring when atoms are submitted to intense infrared laser pulses, with peak intensities 10(14) W cm(-2)
A generalization of the analytical theory of above-threshold ionization in the single active electron approximation is developed while taking into account leading non-dipole and relativistic corrections in the starting Hamiltonian. Special interest is placed on the high energy part of the photoelectron spectrum which consists of a plateau and a ...
of the ionized electron wave packet calculated at a delay of 120 ps for ionization of Xe atoms preparedAbove-threshold ionization in a strong dc electric field Y. Ni,1 S. Zamith,1,2 F. L�pine,1 T received 3 November 2007; published 18 July 2008 High-lying Rydberg states of Xe have been ...
We apply a scattering theory of nonperturbative quantum electrodynamics to study the photoelectron angular distributions (PADs) of a hydrogen atom irradiated by linearly polarized laser light. The calculated PADs show main lobes and jetlike structure. Previous experimental studies reveal that in a set of above-threshold-ionization peaks when the ...
and the electron energy is Ee mec2 . It should be noted that this free-wave acceleration of ionized electronsAbove Threshold Ionization in Tightly Focused, Strongly Relativistic Laser Fields A. Maltsev and T September 2002; published 5 February 2003) The dynamics of electrons ionized from high ...
Two-color above threshold ionization of helium and xenon has been used to analyze the synchronization between individual pulses of the femtosecond extreme ultraviolet (XUV) free electron laser in Hamburg and an independent intense 120 fs mode-locked Ti:sapphire laser. Characteristic sidebands appear in the ...
We present a method for the calculation of multiphoton ionization, including above-threshold ionization and autoionization, which goes beyond the one-electron approximation. We illustrate the method with examples of calculations in He and Mg.
We study above-threshold ionization (ATI) of a one-dimensional model atom in a time-varying external laser field. The time-dependent Schroedinger equation is integrated in space and time using the Crank-Nicholson method, and the photoelectron energy spectrum is then computed by projecting the wave function onto the energy eigenstates ...
We study above-threshold ionization (ATI) of a one-dimensional model atom in a time-varying external laser field. The time-dependent Schr�dinger equation is integrated in space and time using the Crank-Nicholson method, and the photoelectron energy spectrum is then computed by projecting the wave function onto the energy eigenstates ...
We address the problem of calculating electromagnetic transition matrix elements between states of a particle in spherically symmetrical potentials with no assumed boundary conditions at finite distance (free-boundary-condition method). For this, the Schroedinger equation is solved in a finite box of radius R and bound and continuum states, appropriately normalized, are numerically represented, ...
Calculations based on the multiple-scattering method have been performed for the asymmetry parameter (..beta..) as a function of photon energy (from the ionization threshold to 2 Ry above threshold) for the gaseous molecules: N/sub 2/, CO, CO/sub 2/, COS, and CS/sub 2/. For the diatomic molecules N/sub 2/ and CO we have investigated ...
... Accession Number : ADA022036. Title : Photoelectron Spectroscopy of Liquids: External Ionization Energies. Descriptive Note : Technical rept.,. ...
DTIC Science & Technology
An electron imaging technique has been used to study the full angular distribution of valence photoelectrons produced from enantiomerically pure molecular beams of camphor when these are photoionized with circularly polarized light. In addition to the familiar ? parameter, this provides a new chiral term, taking the form of an additional cosine function in the angular ...
Using a frequency-domain theory, we demonstrate that an angle-resolved high-order above-threshold ionization (HATI) spectrum carries three pieces of important information: the fingerprint of the molecular wave function in the direct above-threshold-ionization amplitude, the geometrical structure of the molecule in the potential ...
We analyze the photoelectron emission spectrum in atomic above-threshold ionization by a linearly polarized short-laser pulse. Direct electrons can be characterized by both intracycle and intercycle interferences. The former results from the coherent superposition of two different electron trajectories released in the same optical ...
The development of a new class of laser systems: capable of producing intense radiation in the mid-infrared (MIR) regime (photon energies between 0.3 and 0.4 eV), opens the possibility of observing multiphoton processes in a new class of systems with lower ionization potentials than those previously studied. Of particular interest are the alkali metal atoms, which are true ...
A technique for calculating above-threshold bound-bound transitions of an atomic optical electron, based on the use of generalized Sturm expansion of the Green's function for a potential with a Coulomb asymptotics has been developed within the model-potential method. The dynamic polarizabilities of alkali-metal and noble gas atoms are calculated in the frequency range ...
The highly-nonlinear multiphoton phenomenon of high-energy above-threshold ionization (HATI) of an atomic system by an intense laser field is considered theoretically and studied numerically within frame of a new fully quantum-mechanical strong-field approach developed earlier for effective numerical calculation of high-order harmonic generation spectra ...
Using a triatomic molecular model, we show that the interference pattern in the high-order above-threshold ionization (HATI) spectrum depends dramatically on the charge distribution of the molecular ion. Therefore the charge distribution can be considered a crucial factor for imaging a molecular geometric structure. Based on this study, a general ...
Satellite structure in the Ar K-shell photoelectron spectrum due to M-shell excitations was recorded at X-ray energies 122-422 eV above threshold. Relativistic, multiconfiguration shake-theory calculations give a good overall match to the main satellite features, showing that electron correlation in this case is qualitatively well ...
The theoretical developments presented in a preceding companion paper by Wassaf et al. [Phys. Rev. A 67, 053405 (2003)], for simulating photoelectron spectra, are used to address several issues regarding the harmonic generation process. Both above-threshold Ionization (ATI) and high-order harmonic generation are observed when atoms are ...
We investigate the high-energy above-threshold ionization (HATI) plateau for Xe in a strong laser field at peak intensity of about 0.85�1014W/cm2 with wavelengths of 800, 1250, 1500, and 2000 nm. Numerical simulations are performed using a recently developed quantitative rescattering (QRS) model. According to the QRS model, the two-dimensional (2D) ...
When an electron from a diatomic molecule undergoes tunneling-rescattering ionization, a novel form of destructive interference can be realized that involves all four geometric orbits that are available to the electron when it is freed, because both ionization and rescattering may take place at the same or at different centers. We find experimentally and ...
A method is reported for the determination of ionization energies of liquids or solutions by means of photoelectron spectroscopy (PES). The method is based on the determination of second derivative of the quantum yield (with respect to retarding potential...
National Technical Information Service (NTIS)
... A pulsed-field ionization photoelectron secondary ion coincidence study of the H (X, ve = 0-15, N = 1) + He proton transfer reaction ...
High-order above-threshold ionization by few-cycle laser pulses is analyzed in terms of quantum orbits. For a given carrier-envelope phase, the number of contributing orbits and their ionization and rescattering times determine the shape of the angle-resolved spectrum in all detail. Conversely, analysis of a given spectrum reveals the ...
Ionization of atoms is the first step in many analytical procedures. The cross section for ionizing a particular atomic shell is essential for calculating the magnitude of analytical signals. Calculations using atomic wave functions for various shells of all elements relevant for X-ray microanalysis over a range of electron energies up to 400 keV were ...
The ionization of HCl by electron impact was studied in a mass spectrometer with a pseudomonoenergetic electron beam. The ionization potential of HCl was determined as 12.56 plus or minus 0.1 ev. The ionization curve at threshold exhibits excessive curvature which is attributed to the /sup 2/II/sub i/ doublet ground states ...
We present an application of the artificial-channel method to the calculation of multiphoton ionization rates under continuous-wave illumination conditions. We use the method to treat above-threshold ionization (ATI) of hydrogen in three dimensions with linearly and circularly polarized light at field intensities ranging from 10[sup 9] ...
In a high-intensity laser field an atom can absorb more photons than the minimum necessary for ionization. It is known as above threshold ionization (ATI). Theoretically it is the most difficult case to handle as we have to consider transitions in continuum. To study ATI we use the perturbation theory and Green's ...
... Accession Number : ADA129966. Title : Benzaldehyde Photochemistry Studied with Laser Ionization Mass and Photoelectron Spectroscopy,. ...
-order) above-threshold ionization (HATI) [3�5], nonsequential double (and multiple) ionization and high" (QRS) theory [3,5�9]. Related treatments of HATI without the explicit factorization but which include on the rescattering, or plateau (HATI), electrons whose behavior is calculable by QRS. The major goal of this part
back to its parent ion, off which in the case of high-order above-threshold ionization HATI, this is no longer so, and the additional freedom is reflected in the HATI electron spectrum 5,8 . Laser-atom physics, we will utilize it to analyze HATI by few-cycle pulses. We concentrate on high-order above
The process of above threshold ionization by plane polarized intense radiation fields has enabled cold ionized plasmas to be created. The final temperature depends on the heating process during the laser pulse. Collisional or inverse bremsstrahlung is a major effect at high density. It is argued that under these ...
This paper discusses recent theoretical results on above threshold ionization harmonic generation and high-frequency, high intensity suppression of ionization. These studies of multiphoton processes in atoms and molecules for short, intense pulsed optical lasers have been carried out using techniques which involve ...
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We have calculated the two-photon above-threshold-ionization cross sections of rare-gas atoms by extreme ultraviolet (xuv) photons in the extended framework of multichannel quantum defect theory. Since free-free dipole moments do not converge in the length gauge, we have made the combined use of the length gauge for small r and the acceleration gauge for large r. The ...
Gaseous C{sub 60} has been studied by photoionization mass spectrometry between the ionization threshold and 40.8 eV. An adiabatic threshold of 7.57{plus minus}0.01 eV is observed, which may be slightly low due to hot bands. The energy derivative of the photoion yield curve is in rough agreement with the He I photoelectron spectrum on the positions of some ...
We investigate the cutoff law for high-order above-threshold ionization (HATI) within a semiclassical framework. By explicitly adopting the tunneling effect and considering the initial position shift of the tunneled electron from the origin in the model, the cutoff energy position in HATI spectrum exhibits a well-defined upshift from the simple-man model ...
Total ionization and attachment cross sections have been measured in C/sub 3/F/sub 8/ at 330 K using an electron beam and a total ion collection technique, calibrated by similar measurements on N/sub 2/O and Xe. Our total ionization cross section is similar in general shape to a previous measurement of this type, but with typically half the magnitude. The ...
We theoretically study a process in which helium is doubly ionized by absorbing two soft x-ray (91.45 eV) photons from attosecond, intense high-order harmonic sources. We directly solve the time-dependent Schroedinger equation and obtain electron energy distribution in the double continuum. Our results show that between the two peaks in electron energy spectra, expected for ...
When an infrared laser pulse interacts with atoms or molecules, electrons which are released from the target earlier may be driven back by the laser field to recollide with the target ions. These recollisions incur the well-known strong field phenomena of high-order harmonic generation (HHG) as well as high-energy above-threshold ionization (HATI) ...
We describe the results of experiments performed in Krypton to observe the effect of an isolated atomic level on harmonic generation at intensities above 10(sup 13) W/cm(sup 2). We have measured the intensity of harmonics produced as a function of laser i...
that an angle-resolved high-order above-threshold ion- ization HATI spectrum carries three pieces of important-assisted collisions. As a result all main interference features in the HATI spectrum can be physically explained-threshold ionization HATI 4�8 processes. Odzak and Milosevic 2 showed that clear minima on HHG spectra reveal molecular
laser field. High-order harmonic generation (HHG) and high- energy above-threshold ionization (HATI. In HATI, the returning electrons are backscattered by the parent ion and emerge as high have shown that both HATI and HHG spectra can be accurately calculated using the so-called quantitative
We present molecular above-threshold ionization (MATI) spectra generated by ultrashort intense linearly and circularly polarized laser pulses from nonperturbative numerical solutions of the corresponding time-dependent Schr�dinger equation in the molecular-ion H2+. It is found that high-order MATI spectra with maximum kinetic energy 32Up, where ...
The photoionization dynamics of aniline doped helium droplets has been investigated by photoelectron spectroscopy. The photoelectron spectra resemble closely that of gas phase aniline, except for a droplet-size-dependent shift. This shift is caused by lowering of the ionization threshold upon solvation and can be readily estimated. The ...
... SOLUTIONS(MIXTURES), QUANTUM CHEMISTRY, ENERGY, QUANTUM EFFICIENCY, ABSORPTION SPECTRA, FURANS, GAS IONIZATION. ...
... CHEMICAL BONDS, SPECTRA, MOLECULAR ORBITALS, IONIZATION POTENTIALS, HEAT OF FORMATION, HEAT OF COMBUSTION, HEAT OF ...
... The progress in the use of vacuum ultraviolet photoelectron spectroscopy to detect transient species and obtain ionization potentials and ...
Measurements made with a double ionization chamber reflectance apparatus converted to photoelectron measurement are described. (GHT)
... the integral reaction cross sections ... HYDROGEN, *CHARGE TRANSFER, *ENDOTHERMIC REACTIONS, *PROTON REACTIONS ...
Electrons produced as a result of above-threshold ionization of high-Z atoms can be accelerated by currently producible laser pulses up to GeV energies, as shown recently in Hu and Starace, Phys. Rev. Lett. 88 (2002) Article No. 245003. To describe electron acceleration by general focused laser fields, we employ an analytical model based on a Hamiltonian, fully relativistic, ...
Measurements of energy-resolved angular distributions of electrons generated in above-threshold ionization of rare gases in a field with elliptical polarization are presented, with emphasis on the high-energy part of the spectra. The data show a second plateau at a specific angle with respect to the large component of the laser field. The results are compared to a calculation ...
The results of a theoretical study of HOCO- photodetachment are presented with a view toward understanding the origin of two peaks observed by Lu and Continetti [Phys. Rev. Lett. PRLTAO0031-900710.1103/PhysRevLett.99.11300599, 113005 (2007)] in the photoelectron kinetic energy spectrum very close to threshold. It is shown that the peaks can be attributed to vibrational ...
A relativistic theory of tunneling is developed. Ionization of atoms and ions by a constant crossed field and an ultrashort laser pulse, ionization probability as a function of the adiabaticity parameter and the pulse shape, the limit of the Keldysh nonrelativistic ionization theory, and the photoelectron momentum ...
We report calculations of double-ionization energy spectra and momentum distributions of laser-driven helium due to few-cycle pulses of wavelength 195 nm. The results are obtained from full-dimensional numerical integration of the two-electron time-dependent Schr�dinger equation. A momentum-space analysis of doubly ionizing wavepackets shows that the ...
In the improved strong-field approximation, which describes high-order above-threshold ionization (HATI), the rescattering of the ionized electron on the parent ion is described within the first-order Born approximation. The low-frequency approximation for laser-assisted scattering goes beyond the first Born approximation. In the ...
In this paper, experimental results are presented which clearly demonstrate the effectiveness that an external field has in altering the dissociation dynamics. The experiment examines the strong-field dissociation dynamics of molecular hydrogen ions and its deuterated isotopes. These studies involve multiphoton excitation in the intensity regime of 10[sup 11-14] W/cm[sup 2] with the fundamental ...
In this paper, experimental results are presented which clearly demonstrate the effectiveness that an external field has in altering the dissociation dynamics. The experiment examines the strong-field dissociation dynamics of molecular hydrogen ions and its deuterated isotopes. These studies involve multiphoton excitation in the intensity regime of 10{sup 11-14} W/cm{sup 2} with the fundamental ...
Two-photon above-threshold ionization (ATI) relative cross sections from the 3 {sup 1}P state of Mg have been measured using two-color ionization in the focus of a magnetic bottle spectrometer and have been calculated using the Green's-function method in the Feshbach formalism and an L{sup 2}-integrable close-coupling ...
The ionization potentials of 28 cyclic hydrocarbons including adamantane and several of its derivatives, have been measured from photoelectron spectra. Few of the molecules in this series have been studied previously. The first ionization potentials for a...
The pulse lengths of intense few-cycle (4-10 fs) laser pulses at 790 nm are determined in real-time using a stereographic above-threshold ionization (ATI) measurement of Xe, i.e. the same apparatus recently shown to provide a precise, real-time, every-single-shot, carrier-envelope phase measurement of ultrashort laser pulses. The pulse length is calibrated ...
Results of calculations of the integrated cross section and the energy distribution for ionization of ground-state hydrogen by S1-wave electron impact are presented. The breakup amplitude is expressed as a volume integral that contains an approximate final-state wave function which accounts for postcollision dynamic screening. The error in this wave function is accounted for ...
Many efforts in systematic elucidation of lignin properties start from the properties of the lignin subunits. In this paper, the authors provide the vertical ionization potentials (IP) of a representative set of lignin model compound. Gas phase photoelectron spectroscopy enables them to determine ionization potentials and makes it ...
Development of laser ionization tools toward study of spectroscopy and dynamics of molecules relevant to combustion processes. Ionization versus dissociation was studied in CO(sub 2); the intensity dependence of vibrational structure in photoelectron spec...
Two-photon excitation of a single-photon forbidden Auger resonance has been observed and investigated using the intense extreme ultraviolet radiation from the free electron laser in Hamburg. At the wavelength 26.9 nm (46 eV) two photons promoted a 3d core electron to the outer 4d shell. The subsequent Auger decay, as well as several nonlinear above ...
The plateaus in laser-assisted recombination and high-order harmonic generation are investigated in the frequency domain. It is found that the probability amplitude of finding an electron with a given energy is given by a generalized Bessel function, which can be represented as a coherent superposition of contributions from a few electronic quantum trajectories. This concept is illustrated by ...
The pulse shape and phase of isolated attosecond extreme ultraviolet (XUV) pulses with a duration of 860 asec have been determined simultaneously by using frequency-resolved optical gating based on two-photon above-threshold ionization with 28-eV photons in He. From the detailed characterization, we succeeded in shaping isolated XUV pulses on an attosecond ...
We report on the direct observation of an attosecond pulse train with a mode-resolved autocorrelation technique. The chirp among the three harmonic fields is specified by analyzing two-photon above-threshold ionization spectra of electrons, resulting in a pulse duration that should be shorter than 450 as, which is, to our knowledge, the first determination ...
. TABLE II: "Raw" formation enthalpies HATi , HVTi (from Eqs. (2-3) at zero pressure), "true" formation. A HATi HA Hls,nv sol Zn 6.405 -0.262 0.218 Cd 7.267 0.24 0.461 Ag 5.412 0.304 0.494 Au 3.882 -0.781 0
We present measurements of the absolute rates for multiphoton ionization of the ground state from atomic hydrogen by a linearly polarized, subpicosecond KrF laser pulse at a wavelength of 248 nm. A laser crossed atomic beam technique is used. The irradiance was varied from 3{times}10{sup 12} w/cm{sup 2} to 2{times}10{sup 14} w/cm{sup 2} and three above ...
The 100 keV photo-electron guns at Jefferson Lab have demanding vacuum requirements since the photo-cathode lifetime is decreased by residual gas ionization and photocathode ion back-bombardment.
Photoelectron spectra of vinyl halides, vinyl methyl ether, allyl halides and allyl alcohol have been measured in the range 6-21 eV. Ionization potentials have been determined for each molecule, and assigned in some cases to specific molecular orbitals. V...
The photoelectron spectra of 67 organic compounds, including paraffins, cycloparaffins, olefins, dienes, aromatic hydrocarbons, alcohols, ethers, aldehydes, ketones, and diene iron tricarbonyl complexes, were measured, using a simple retarding-potential g...
The Helium (I) photoelectron spectra of benzo and naptho derivatives of 1,1-diphenylmethylenecyclopropene (DPMC) are presented. A correlation of electro-chemical oxidation potentials E sub 1/2 (+) values and gas phase ionization potentials of a series of ...
The principle behind the Cherenkov Ring Imaging Detectors (CRIDs) involves focussing the Cherenkov light, emitted by a relativistic charged particle in passing through a radiator medium, onto a high efficiency photocathode which can be in turn read out with good spatial resolution, to localize the point of origin of the photoelectrons. This information permits the ...
Nonlinear electron emission processes induced by surface plasmon oscillations have been studied both experimentally and theoretically. The measured above-threshold electron spectra extend up to high energies whose appearance cannot be explained solely by standard non-perturbative methods, which predict photon energy separated discrete energy line spectra with the known fast ...
The photoionization of aromatic molecules (aniline, phenol, and toluene) in helium droplets was studied with photoelectron spectroscopy. The photoelectron spectra resemble closely those of gas phase molecules except for the droplet size dependent shift. This shift is caused by the lowering of the ionization threshold upon solvation and ...
Angular distributions of photoelectrons, produced by single ionization of ethylene or benzene molecules with an intense linearly polarized laser field, are calculated. The anisotropy and the yield of the photoelectrons depend strongly on the orientation between the molecular geometry and the field. In particular, electron emission in ...
Studies of nonlinear laser-matter interaction have been so far limited to wavelengths from the near ultraviolet to infrared, because of the low brightness of currently available sources outside this range. However nonlinear processes in the VUV/Soft X-ray domain would initiate multiphoton innershell spectroscopy, XUV nonlinear optics and applications of such processes to metrology. The probability ...
We present photoelectron measurements from argon ionization at 10(19) W/cm(2). Photoelectrons with energies above 400 keV, including a 1.2 MeV cutoff, are in quantitative agreement with a semiclassical, relativistic 3D ionization model that includes a nonparaxial laser field. L-shell ...
We present photoelectron measurements from argon ionization at 1019W/cm2. Photoelectrons with energies above 400 keV, including a 1.2 MeV cutoff, are in quantitative agreement with a semiclassical, relativistic 3D ionization model that includes a nonparaxial laser field. L-shell photoelectrons ...
Double resonance spectroscopy via theEF ^1?g^+ ,v'EF=6,J' state has been used to probe the H(n=1) + H(n=3) dissociation threshold region with quantum state selectivity and high energy resolution. Above threshold the continuum is detected by ionizing H(n=3) to produce H^+, which is then detected by using a time-of-flight mass ...
A systematic study is reported on the convergence of computed triply differential cross sections for photo-double ionization of helium at 20 and 25 eV above threshold, obtained using the hyperspherical R matrix with semiclassical outgoing waves method. Such a study has become feasible due to an essential improvement in the ...
... Abstract : By analyzing the photoelectron energies in several systems, it has been demonstrated that multiphoton ionization (MPI) can selectively ...
... Coupling this with state-selective product ion ... 2 A. Resonance-Enhanced Multiphoton Ionization-Photoelectron Spectroscopy ... d) [N - (N, +IR)] + (p* -p ...
Photoelectron spectroscopy has been performed to study the multiphoton double ionization of Ar in an intense extreme ultraviolet laser field (h? ? 21 ?eV, ? 5 ?TW/cm�), by using a free electron laser (FEL). Three distinct peaks identified in the observed photoelectron spectra clearly show that the double ...
Measurements made with a double ionization chamber reflectance apparatus converted to photoelectron measurement are described. (ERA citation 05:026492)
The generation of highly charged Xe(q+) ions up to q=24 is observed in Xe clusters embedded in helium nanodroplets and exposed to intense femtosecond laser pulses (?=800??nm). Laser intensity resolved measurements show that the high-q ion generation starts at an unexpectedly low threshold intensity of about 10(14)??W/cm2. Above threshold, the Xe ion charge ...
The generation of highly charged Xe{sup q+} ions up to q=24 is observed in Xe clusters embedded in helium nanodroplets and exposed to intense femtosecond laser pulses ({lambda}=800 nm). Laser intensity resolved measurements show that the high-q ion generation starts at an unexpectedly low threshold intensity of about 10{sup 14} W/cm{sup 2}. Above ...
The generation of highly charged Xeq+ ions up to q=24 is observed in Xe clusters embedded in helium nanodroplets and exposed to intense femtosecond laser pulses (?=800nm). Laser intensity resolved measurements show that the high-q ion generation starts at an unexpectedly low threshold intensity of about 1014W/cm2. Above threshold, the Xe ion charge ...
Numerical results obtained applying the strong-field approximation to atomic and molecular processes in intense laser fields are presented. In particular, the forward-backward asymmetry in high-order above-threshold ionization (HATI) of Ar atoms by a few-cycle laser pulse is considered. It is shown that the resonantlike enhancements observed in the ...
Generalized oscillator strengths and ionization cross sections by fast electron impact are calculated for K, L, and M shells. A nonrelativistic Hartree--Slater program is used to generate the initial states as well as the continuum wave functions. Core edge shapes and their dependence on momentum transfer are computed within this atomic model up to some tens or hundreds of eV ...
We calculate angle-resolved above-threshold ionization spectra for diatomic molecules in linearly polarized laser fields, employing the strong-field approximation. The interference structure resulting from the individual contributions of the different scattering scenarios is discussed in detail, with respect to the dependence on the internuclear distance ...
We have calculated, independently, the {sup 1}S singly differential cross section for the electron-impact ionization of hydrogen at an incident energy of 4.0 eV above threshold using two different methods: time-dependent close coupling and exterior complex scaling. The absolute value of the {sup 1}S cross section for equal energy ...
The threshold law of the titled process, which is of the same form as that for electron-impact ionization of H, can experimentally be contaminated by simultaneous single photodetachment and Rydberg excitation of the residual atom, followed by ionization of the Rydberg atom by (room-temperature) blackbody photons. This gives a signal indistinguishable from ...
The dynamics of highly charged ions in a strong laser field are investigated by solving the two-dimensional time-dependent Dirac equation. Relativistic effects are discussed for the hydrogen-like ions with nuclear charges of Z=4, 24 and 79 by considering the changes in the electron trajectory and coherent emission spectrum with changes in the frequency and intensity of the laser field. With ...
Electron impact ionization has several known advantages; however, heated filament electron sources have pressure limitations and their power consumption can be significant for certain applications, such as in field-portable instruments. Herein, we evaluate a VUV krypton lamp as an alternative source for ionization inside the ion trap of a mass ...
Time-resolved photoelectron spectroscopy is a powerful technique for the study of real-time electron dynamics on metallic surfaces. These studies are performed in pump-probe geometries, where a pump pulse excites a dynamic process and a time-delayed probe monitors changes in the system. Furthermore, recent progress in ultrafast lasers and high-harmonic generation has opened up ...
A non-perturbative approach to the theory of multiphoton ionization is reviewed. Adiabatic Floquet theory is its first approximation. It explains qualitatively the energy and angular distribution of photoelectrons. In many-electron atoms it predicts collective and inner shell excitation. 14 refs.
A non-perturbative approach to the theory of multiphoton ionization is reviewed. Adiabatic Floquet theory is its first approximation. It explains qualitatively the energy and angular distribution of photoelectrons. In many-electron atoms it predicts colle...
objectives of this research are the development and application of theoretical techniques for studying several resonant multiphoton ionization processes in molecules. Specific problems of interest pertain to experimental studies of such spectra in which the photoelectron energy and angular distributions are determined.
The ionization potential of O2 was measured by the technique of high resolution photoelectron spectroscopy taking into account the influence of rotational structure on the shape of the vibrational bands. A value of 12.071 + or - .001 eV (1027.1 + or - 0.1...
Multiphoton ionization of CCl/sub 3/F by an ArF laser is studied for processes in which extensive and sequential fragmentation taken place. (AIP)
This reprint reports a two-color high-resolution energy- and angle-resolved study of the photoelectrons produced in the (1+1) REMPI of NO via rotational levels of the A 2 sigma (+) nu=0 state. Markedly different photoelectron angular distributions arise f...
A new apparatus has been constructed that combines electrospray ionization with a quadrupole mass filter, hexapole ion trap, and velocity-map imaging. The purpose is to record photoelectron images of isolated chromophore anions. To demonstrate the capability of our instrument we have recorded the photodetachment spectra of isolated deprotonated phenol and ...
The deviations from Koopmans' one-electron model of photoionization which lead to satellite structure in the photoelectron spectrum are examined within the formalism of configuration interaction (CI). The mechanisms which contribute to satellite intensity may be classified as continuum state configuration interaction, final ionic state configuration interaction, and ...
Three-photon ionization cross sections from the ground state, and two-photon ionization from the 3 {sup 1}P(3s3p) state have been calculated for Mg in the region between the 3p and 4s ionization thresholds. These processes include an above-threshold ionization process for the last absorbed photon. We have used the ...
The resonantly enhanced multiphoton ionization of atomic hydrogen is studied for the case of four-photon ionization (three-photon resonant). The time-dependent probabilities, the shape of the resonance profile at different intensities, and the nonlinear index are computed for coherent light at frequencies around the resonance (365 nm). The systematic ...
Above-threshold ionization (ATI) ionization by linearly polarized light has been proposed by several authors as a means of driving recombination lasers in the soft x-ray spectral region. The pump radiation generates a cold electron plasma with ions in a single ionization stage, which is an ideal starting condition ...
The balance of the linear photon momentum in multiphoton ionization is studied experimentally. In the experiment argon and neon atoms are singly ionized by circularly polarized laser pulses with a wavelength of 800 and 1400 nm in the intensity range of 10(14)-10(15)??W/cm2. The photoelectrons are measured using velocity map imaging. We ...
The balance of the linear photon momentum in multiphoton ionization is studied experimentally. In the experiment argon and neon atoms are singly ionized by circularly polarized laser pulses with a wavelength of 800 and 1400 nm in the intensity range of 1014�1015W/cm2. The photoelectrons are measured using velocity map imaging. We ...
Two- and three-photon ionization processes in cesium atoms using a single pulsed-dye laser and a cesium atomic beam have been investigated. Photoelectron angular distributions have been measured for two-photon resonant, three-photon ionization via the nd states (n = 12, 15, and 21), for two-photon nonresonant transitions over the ...
We study elastic scattering and impact ionization by returning electrons induced in a strong laser field based on the recently developed quantitative rescattering theory. The high-energy angle-resolved photoelectron spectra of molecules in strong fields are attributed to elastic scattering of the returning electrons with the parent ion. We demonstrate that ...
The high-resolution photoionization and pulsed-field ionization zero-kinetic energy (PFI-ZEKE) photoelectron spectra of propene and 2-butyne and their perdeuterated isotopologues have been recorded in the vicinity of the first adiabatic ionization energy following single-photon excitation from the neutral ground state using a ...
Photoelectron ionization spectra of a system interacting with a neighbor two-level atom are investigated using the Laplace-transform method. These spectra are typically composed of several peaks. Photoelectron ionization spectra conditioned by the measurement on the two-level atom show oscillations at the Rabi ...
The ultraviolet photoelectron spectra (UPS) of oxalic, malonic, succinic, glutaric, and adipic acids, and various of their simple derivatives, are presented and discussed. The four lowest-energy ionization events, (I(n/sub +/), I(n/sub -), I (..pi../sub +/), I(..pi../sub -/)), are assigned in all cases. Higher ionization events are not ...
A molecular beam of phenol, cooled by a supersonic expansion, is crossed at right angles by the output of a pulsed frequency-doubled dye laser, causing 1 + 1 resonance enhanced multiphoton ionization. The kinetic energy of the resulting photoelectrons is ...
The He(I) photoelectron spectra of atomic scandium and vanadium have been recorded in the gas-phase. For scandium two bands associated with a 1/4s ionization and one band associated with a 1/3d ionization of the neutral atom have been observed. Measuremen...
The novel technique of femtosecond time-resolved photoelectron-photoion coincidence imaging is applied to unravel dissociative ionization processes in a polyatomic molecule. Femtosecond coincidence imaging of CF3I photodynamics illustrates how competing multiphoton dissociation pathways can be distinguished, which would be impossible using ...
Ab initio calculations have been performed to study the molecular structures and the vibrational levels of the low-lying ionic states (2A2, 2B1, 2A1 and 2B2) of thiophene. The equilibrium molecular structures and vibrational modes of these states are presented. The theoretical ionization intensity curves including the vibrational structures of the two low-lying ionic states ...
The quantitative relation between fast electron impact and photoabsorption is discussed with reference to simulation of the technique of photoelectron spectroscopy. An apparatus is described that employs coincidence detection of scattered and ejected electrons resulting from ionization over a range of energy losses up to 70 eV. Absolute ...
We use the S-matrix formalism in order to investigate the possible role of incoherent scattering in different processes in a strong laser field. In the cases of above-threshold ionization (ATI) of atoms and above-threshold detachment (ATD) of negative ions, we assume that the ionized (detached) electron may scatter off a target other than its parent ion ...
We calculate the angular distribution of photoelectron from aligned N2 and CO2 molecules in the photoionization process. The molecules are first exposed to a pump IR laser which creates molecules that are transiently aligned or anti-aligned. These molecules are then probed by absorbing a single XUV photon (through high-order harmonic generation ) with the emission of ...
Two- and three-photon ionization processes in cesium atoms using a single pulsed-dye laser and a cesium atomic beam have been investigated. Photoelectron angular distributions have been measured for two-photon resonant, three-photon ionization via the nd ...
The mechanism of collision-free multiphoton ionization of rare gases irradiated with ultraviolet radiation at an intensity of up to approx.10/sup 16/ W/cm/sup 2/ at 248 nm and a pulse length of approx.0.5 ps and approx.10/sup 15/ W/cm/sup 2/ at 193 nm and approx.5ps, respectively, has been studied by observing the electron energy spectra and ion charge state threshold ...
By numerical solution of the time-dependent Schroedinger equation, highly accurate electron spectra are calculated for strong-field ionization of a one-dimensional H{sub 2}{sup +} molecular ion at large internuclear distances. Compared to the atomic spectra, we find additional cutoffs at high electron energies. The classical model for ionization ...
Three-photon double ionization of an Ar atom has been investigated by photoelectron spectroscopy using an extreme ultraviolet free-electron laser. When the photon energy of the laser has been tuned to the resonances of the intermediate Ar+ ion, photoelectron peaks due to the resonant two-photon single ionization of ...
We report the first observation, together with a mechanism for such an observation, of a steplike feature in the pulsed field ionization photoelectron measurement of CH4(C2H2), marking the 0 K dissociation threshold for the formation of CH3(+) + H(C2H(+) + H) from CH4(C2H2). The nonexistence of a step in the spectrum for C 2H4 at its dissociation threshold ...
The ability of neighboring C-Si, C-Sn, and Si-Si groups in conformationally constrained cyclic molecules to reduce the lowest ionization energies of sulfur, selenium, and tellurium compounds has been determined by charge-transfer spectroscopy of complexes with tetracyanoethylene. For selected compounds, ionization energies were determined by gas-phase ...
According to the quantitative rescattering (QRS) theory, the high-energy Above-threshold-ionization (HATI) electron spectra from a molecule M can be used to extract the differential cross section (DCS) at large scattering angles for e- + M+ collisions. Using mid-infrared (MIR) lasers the rescattering electrons can reach energies from 50 eV to a few hundred eV's where the ...
In this Letter we demonstrate a method for real-time determination of the carrier-envelope phase of each and every single ultrashort laser pulse at kilohertz repetition rates. The technique expands upon the recent work of Wittmann and incorporates a stereographic above-threshold laser-induced ionization measurement and electronics optimized to produce a ...
Polar photodissociation of CF{sub n}Cl{sub 4-n} (n=0-2) has been studied using synchrotron radiation within the energy range 195-217 eV. The first observations of negative photoion fragments from these molecules after core excitation are reported. In addition to observing a number of previously known resonances two additional resonant states, just above the Cl 2p ionization ...
Polar photodissociation of CFnCl4?n(n=0-2) has been studied using synchrotron radiation within the energy range 195-217 eV. The first observations of negative photoion fragments from these molecules after core excitation are reported. In addition to observing a number of previously known resonances two additional resonant states, just above the Cl2p ionization limit, are ...
The occurrence of a fault April 7 caused a short in the stator winding of one of the main generators. Repairs will require at least one month and the total time the generator will be down can be determined only after a further inspection of the damage. In a week or two, after a thorough inspection of the generator and the ignitron system, Bevatron operation will be continued on one generator. ...
Experimental and theoretical results are presented for electron impact ionization of water in the energy regime from near threshold to intermediate energies. Results were taken in symmetric coplanar and non-coplanar geometries, with both equal and non-equal outgoing electron energies. The models approximate the random orientation of the target using a spherical averaging of ...
At high intensities, three-step recollision processes driven by low frequency laser pulses, such as high-order harmonic generation and high-order above-threshold ionization, are normally severely suppressed by the magnetic-field component of the laser field. It is shown that this suppression is not severe, even for ponderomotive energies well above 10 keV, ...
We present a first-principles description for the electron dynamics and multiphoton absorption in crystalline SiO(2) induced by an optical field. We rely upon time-dependent density-functional theory with adiabatic local-density approximation, and a real-space and real-time method is employed to solve the time-dependent Kohn-Sham equation. Computational results show the absorption of photons to be ...
Photoelectron angular distributions have been investigated in cesium, rubidium, and sodium atoms using resonant and nonresonant multiphoton excitation techniques. The experiments have been carried out by using a frequency -tunable dye laser as the excitation light source and a spherical sector electrostatic energy analyzer in conjunction with a dual channel plate detector. ...
Electron impact ionization has been studied in PH/sub 3/ and in a mixture of PH/sub 3/ and PD/sub 3/ as a function of electron energy up to 180 eV, with a double focusing mass spectrometer. Absolute partial ionization cross sections have been obtained in PH/sub 3/ for the production of the parent ion PH/sup +//sub 3/, for the fragment ions PH/sup +//sub ...
Ionization is the dominant response of atoms and molecules to intense laser fields and is at the basis of several important techniques, such as the generation of attosecond pulses that allow the measurement of electron motion in real time. We present experiments in which metastable xenon atoms were ionized with intense 7-micrometer laser pulses from a ...
High precision photoelectron energy and angular distributions in helium and neon atoms for a broad intensity range reflect the change in the continuum dynamics that occurs as the ionization process evolves into the pure tunneling regime. Elastic rescattering of the laser-driven free electron from its parent ion core leaves a distinct signature on the ...
Photoelectron ionization spectra of an autoionization system with one discrete level interacting with a neighbor two-level atom are discussed. The formula for long-time ionization spectra is derived. According to this formula, the spectra can be composed of up to eight peaks. Moreover, the Fano-like zeros for weak optical pumping are ...
Multiple photoionization of neon atoms by a strong 13.7 nm (90.5 eV) laser pulse has been studied at the FLASH free electron laser in Hamburg. A velocity map imaging spectrometer was used to record angle-resolved photoelectron spectra on a single-shot basis. Analysis of the evolution of the spectra with the FEL pulse energy in combination with extensive theoretical ...
Solar radiation below 50 nm produces a substantial portion of the F region ionization and most of the E region ionization that drives chemical reactions in the thermosphere. Because of a lack of high temporal and spectral resolution Solar EUV and XUV observations, particularly below 27 nm, various solar irradiance models have been developed. We have ...
Theoretical and experimental studies show the strong influence of the three-photon nearly resonant 2{ital p} state on four- and five-photon ionization of atomic hydrogen near the threshold for four-photon ionization. Changes in five-photon ionization occur when the four-photon ionization channel opens. The angular ...
Monochromatized synchrotron radiation from a focused 8-pole wiggler beam line has been used to excite the L/sub 2/ and L/sub 3/ holes of atomic Xe and the K hole of atomic Ar near their photoionization thresholds. The Xe L/sub 3/-M/sub 4/M/sub 5/ (/sup 1/G/sub 4/) Auger line, the Xe L/sub 2/-L/sub 3/N/sub 45/ Coster-Kronig line, and the Ar K-L/sub 23/L/sub 23/ Auger line with incident x-ray ...
Monochromatized synchrotron radiation from a focused 8-pole wiggler beam line has been used to excite the L2 and L3 holes of atomic Xe and the K hole of atomic Ar near their photoionization thresholds. We have measured the Xe L3-M4M5 lpar1G4rpar Auger line, the Xe L2-L3N45 Coster-Kronig line, and the Ar K-L23L23 Auger line with incident x-ray energies from ~20 eV below threshold to ~200 eV ...
This study reveals that the ratios of the photoelectron to EUV ionization rates are not constant but depend on the degree of attenuation of the solar EUV flux and on the transport of photoelectrons. At high altitudes in the absence of photoelectron transport, the O{sup +} and N{sub 2}{sup +} ...
It is found that the mean charge of tungsten ions in a solid tungsten target cleaned from the surface layer of hydrocarbon and oxide compounds and exposed to femtosecond laser radiation with an intensity exceeding 10{sup 16} W/cm{sup 2} attains 22+, while the maximum charge is 29+. The maximum energy of such ions approaches 1 MeV. The corresponding values obtained on a dirty target with the same ...
We present evidence of a cold multiphoton MALDI process occurring at a Room Temperature Ionic Liquid (RTIL)/metal interface. Our RTIL, 1-Butyl-3-methylimidazolium hexafluorophosphate, remains a stable liquid at room temperatures, even at pressures lower than 10-9 torr. We focus the 2^nd harmonic of a pulsed (2ns pulse length) Nd:YAG laser onto a gold grid coated with RTIL to generate a cold ...
In this final report the author presents a summary of recent research accomplishments. In this grant period (FY90--97), some 36 papers have been published. [See Part 4 for a list of publications]. Significant progress has been made in several areas, both in the development of new theoretical and computational methods, their applications to experimental observations, and in the prediction of some ...
We investigate photoelectron kinetics in advanced quantum dot (QD) structures, which combine quantum tuning of localized and conducting states with controllable photoelectron properties. Our unique approach is based on engineering of photoelectron capture processes using various configurations of manageable potential barriers around ...
We have used cold target recoil ion momentum spectroscopy to study the continuum correlation between the photoelectron of core-photoionized neon and the subsequent Auger electron. We observe a strong angular correlation between the two electrons. Classical trajectory Monte Carlo calculations agree quite well with the photoelectron energy distribution that ...
Synchrotron radiation (SR) has a variety of properties which make it an attractive source for quantitative x-ray photoelectron spectroscopy (XPS). Among the most significant are high intensity and tunability. In addition, the intensity of the dispersed radiation is comparable to laboratory line sources. Synchrotron radiation is also a clean source, i.e., it will not ...
Avalanche detection of a laser enhanced ionization (LEI) signal has been studied in a resonance ionization detector (RID) cell containing mercury vapor at room temperature. Single photoelectron events were detected with an avalanche multiplication factor of more than 8000. {copyright} {ital 1997 American Institute of Physics.}
Avalanche detection of a laser enhanced ionization (LEI) signal has been studied in a resonance ionization detector (RID) cell containing mercury vapor at room temperature. Single photoelectron events were detected with an avalanche multiplication factor of more than 8000.
We report measurements of multiphoton ionization of CO involving a three photon resonance to the v=1-3 levels of the CO A exp 1 PI state followed by the absorption of either two (v=3) or three (v=1,2) additional photons to reach the ionization continua. I...
Progress is reported on measurements of vibrational fine structure in the valence ionizations of group IVB hexacarbonyls; the Jahn-Teller effect in the photoelectron spectrum of Fe(CO)/sub 5/; the effects of methyl group substitution on metal-coordinated cyclopentadienyl rings; valence ionizations of olefins coordinated to metals; and ...
The dynamics of electronically excited helium nanodroplets are studied by femtosecond time-resolved photoelectron imaging. EUV excitation into a broad absorption band centered around 23.8 eV leads to an indirect photoemission process that generates ultraslow photoelectrons. A 1.58 eV probe pulse transiently depletes the indirect photoemission signal for ...
Helium droplets doped with Xe and Kr atoms were photoionized by using VUV synchrotron radiation from the Advanced Light Source and the resulting photoelectron images were measured. A wide range of He droplet sizes, photon energies, and dopant pick-up conditions was investigated. Significant ionization of dopants was observed at 21.6 eV, the absorption ...
The dynamics of electronically excited states in 2-picoline is studied using femtosecond time-resolved photoelectron imaging spectroscopy. The internal conversion from the S2 state to the vibrationally excited S1 state is observed in real time. The secondarily populated high vibronic S1 state deactivates further to the S0 state. Photoelectron energy and ...
The photoabsorption spectra and the photoelectron-yield spectra in the vacuum-uv region between 1050 and 2400 A have been measured for the aliphatic homopolypeptide films poly(glycine), poly(L-alanine), and poly(L-valine). By comparing the photoabsorption spectra with the photoelectron-yield spectra, the existence of highly excited states at excitation ...
The injection of photoelectrons into a gaseous or liquid sample is a widespread technique that is used to produce a cold plasma in a weakly ionized system to study the transport properties of electrons in a dense gas or liquid. We report here the experimental results of the collection efficiency of photoelectrons injected into dense ...
We present results of calculations of the angular distributions of K-shell photoelectrons from fixed-in-space CO and N{sub 2} molecules emitted by circularly polarized light. These calculated distributions account well for the strong circular dichroism recently reported in measurements of photoelectron distributions in these two systems. The calculations ...
Using high-resolution photoelectron spectroscopy and 120-fs, 800-nm Ti:sapphire laser pulses, we observe and analyze intensity-dependent resonant population of specific intermediate excited states of neutral magnesium atoms and their subsequent photoionization in the laser field. Various participating states are identified using angular-momentum selection rules, partial ...
We theoretically study strong-field ionization of a heteronuclear diatomic molecule, CO, by calculating the photoelectron angular distributions (PADs) and the total ionization rates using linearly and circularly polarized laser fields. We find that, although the PADs of CO generally do not have inversion symmetry, they become more ...
... WERE DETERMINED SUCH AS SIGNAL DURATION, AE COUNTS (OSCILLATIONS ABOVE THRESHOLD), RISE TIME, AND PEAK AMPLITUDE. ...
Discrete vibrational structure has been observed in the photo-electron spectrum of oxygen at an ionization potential of 40.33 eV. Two levels, attributed to the 02(+) 2 sigma g- final state, have been detected with a vibrational spacing of 0.071 eV. (Autho...
A new type of time-resolved photoelectron spectroscopy experiment is presented: the ESCA shifts of the 4d fine structure split core-level of iodine atoms in the iodophenylphenol molecules adsorbed perpendicular to the (100) surface of silicon has been studied and observed transiently in fs-time resolved photoelectron spectroscopy as a function of the delay ...
The HeI photoelectron and far ultraviolet absorption spectra of formaldoxime (CH2=N-OH) and three other simple nonconjugated oximes are reported and compared to those of simple imines. Contrary to imines the lowest ionization potential seems to be related to the ? orbital although this assignment must be considered tentative. In the uv spectrum the ...
Threshold energies (6.1 less than E sub t equal to or lesser than 8.6 eV) are determined for photoelectron emission by 16 inorganic cations in aqueous solution. E sub t's are correlated with gas-phase ionization potentials, solvation and reorganization fr...
The He(I) photoelectron spectra of lithium, sodium and potassium hydroxide have been recorded and assigned using ab initio molecular orbital calculations. For all three hydroxides, bands associated with ionization of monomers and dimers are observed and t...
Helium 584 � radiation produces photoelectron spectra from water and deuterium oxide, which show extensive vibrational fine structure. The results are discussed in terms of the electronic structure of the molecule, and the bonding characteristics of the various molecular orbitals. Water is inferred to have only three configurationally distinct ionization ...
We analyze correlated photoelectron spectra of single-photon two-electron ionization [double photoionization (DPI)] of helium to reconstruct the phase of the spectral amplitude of this process. The phase can be reconstructed reliably in a wide range of photoelectron momenta, thus allowing one to retrieve information about the wave ...
Semi-empirical valence electron model calculations are used to interpret photoelectron spectra for the two to three smallest ionization energies in atomic complexes of the first two rows of the periodic system with an error of less than 1 eV. It is possib...
Spectra and angular distributions of photoelectrons from ionization of atoms by a combination of two short pulses in the XUV and IR range are theoretically considered. The transition from the streaking regime for ultrashort XUV pulses to the sideband formation for longer pulses is discussed. For photoelectrons of sufficiently high ...
Ion back-bombardment is the dominant mechanism that limits the operating lifetime of DC high voltage GaAs photoelectron guns. In this work, an electrically isolated anode electrode was used to distinguish the QE damage contributions of ions produced within the cathode/anode gap and those produced downstream of the anode. This new anode design provides a means to suppress QE ...
