A UV photoelectron spectrometer featuring rapid analysis

An improved sensitivity electron spectrometer for use in UV photoelectron spectrometry has been developed for rapid analysis. High sensitivity is achieved by the use of a focal-plane position-sensitive multidetector consisting of a linear array of photosensitive diodes (a CCD imaging device) allowing parallel detection and rapid data-acquisition. In the measurement of the He (I) 58.4 nm photoelectron spectrum of Ar, the gain in acquisition time is estimated to be by a factor of ～12.     

An electron-retardation device to improve the resolution of a turner-type UV photoelectron spectrometer

A simple pre-retardation device without intermediate images that may be used to increase the resolution of Turner-type UV photoelectron spectrometers has been analyzed by means of electron trajectory calculations. A set of qualitative rules based on the calculations as well as performance tests of the actual device are presented. High-resolution spectra of naphthalene and anthracene are presented as an illustration and compared in detail with recent model calculations of Franck—Condon profiles by Ohno [9].     

A three-element cylindrical electrostatic lens for a photoelectron spectrometer

The properties of a three-element electrostatic lens for use in photoelectron spectroscope is reported. The lens, which keeps a constant focal position over a wide range of photoelectron kinetic energies, is coupled to a high resolution hemispherical electrostatic analyzer. Maximum utilization of the electron optics is described.     

Auger signals obtained with a photoelectron spectrometer

If the initial ionization energy of a system emitting an Auger electron needs an energy somewhat below the mono-energetic photons used in a photoelectr     

A traceable quantification procedure for a multi-mode X-ray photoelectron spectrometer

A modification to the quantification procedure used by a multi-mode X-ray photoelectron spectrometer (XPS) instrument is described which enables transfer of quantification between instruments, and which is referenced to a verified source. The procedure takes account of the intensity/energy response function of the instrument, which is appended to the data file, eliminating ambiguities in intensity calibration at a later date, and allowing background subtraction techniques based on electron scattering to be used on corrected spectra. A strategy is proposed to minimise inaccuracies arising from surface contamination and low signal intensity. Use of the procedure is illustrated by comparing quantification using different data processing software.     

A variable angle photoelectron spectrometer using a position-sensitive detector

A variable angle photoelectron spectrometer utilizing a position-sensitive multidetector is described. Photoelectron spectra of N₂ obtained using a synchrotron radiation source are presented. The data are acquired using a new technique in which the photoelectron yield is obtained as a function of both wavelength and photoelectron energy, and this gives detailed information on autoionization processes.     

A cheap versatile ultraviolet photoelectron spectrometer

The design, construction and operation of an ultraviolet photoelectron spectrometer are reported. It has a readily accessible target chamber and a versatile inlet system, which can cope with a rapid throughput of relatively involatile samples. The electrons emerging from the target chamber pass through two slits which are subject to a variable electric field, into a magnetic field. Thus the spectrum is linear. The resolution based on argon ²P_{$\text{3}\text{2}$} peak is 18 meV. The instrument is easy to make and operate. It is proving adequate for many chemical and analytical purposes and may be coupled directly to a gas-liquid chromatograph. Problems encountered during construction and optimization are discussed.     

Ion source with electron ionization for a portable mass spectrometer

An ion source with electron ionization is considered. The charged-particle flow at the exit from this source has a cross section of ∼0.1 × 0.1 mm, an angle spread of 2° × 2°, a relative energy spread of <0.5%, and an energy range of 0.5–3.0 keV. This ion source is intended for systems where an ion beam is focused in two mutually perpendicular directions. The ion source design makes it possible to ionize a sample locally (in a volume of ∼10 mm³), where the concentration of the particles under study exceeds the concentration averaged over the volume of the vacuum chamber of the mass spectrometer by two to three orders of magnitude. The ion-optical properties of the source are numerically simulated, and the optimum parameters of the source are chosen. Examples of the application of the ion source are given for the mass-spectrometric determination of metal salts in aqueous solutions and of gases and volatile compounds in samples in various phase states.     

Electrical characteristics of an X-ray photoelectron spectrometer

Current-voltage characteristics have been measured for an AEI ES200B X-ray photoelectron spectrometer with both conducting and insulating samples. With the conducting sample, the flux of secondary electrons falling on the specimen and probe amounts to approximately 20 percent of the photoelectron flux, over a wide range of irradiation conditions. The results for the insulating sample, taken in conjunction with subsidiary data from charging shifts, indicate that the secondary flux incident on the specimen alone exceeds 99 percent of the photoelectron flux.     

Mapping the fermi surface of graphite with a display-type photoelectron spectrometer

A display spectrometer is used to image the momentum distribution of photoelectrons from the Fermi level in graphite. The Fermi surface consists of six points at the corners K of the hexagonal, two-dimensional Brillouin zone, in agreement with band theory. The method is also applied to other equal energy surfaces below the Fermi level, thereby giving the band dispersion of the -bands.     

UV photoelectron spectra of adsorbed cyclopentadienyl

Angle resolved photoelectron spectra stimulated by synchrotron radiation are reported for cyclopentadienyl (Cp) adsorbed on Rh(III). Molecular orbital assignment of Cp derived photoemission bands is attempted by comparison with gas phase monometal-Cp complexes, MO calculations and by considering polarisation dependence and angular variation in the present oriented-molecule spectra. The spectra are discussed in terms of the intramolecular symmetry and of the symmetry of the total adsorption complex.     

Shaper-assisted full-phase characterization of UV pulses without a spectrometer

A full-phase measurement of low-energy femtosecond UV pulses is presented. The method relies on phase retrieval of measured sonogram traces and is greatly simplified by a two-dimensional shaper-assisted cross correlation setup. As all required pulses are generated by the pulse shaper, the method is free of external references and additional tunable filter setups.     

Repeatable intensity calibration of an X-ray photoelectron spectrometer

Ten years ago, NPL developed an infrastructure for calibrating the intensity response functions of electron spectrometers for Auger electron and for X-ray photoelectron spectroscopies. Two software systems were developed: one for Auger electron spectrometers or for Auger electron and X-ray photoelectron spectrometers combined, and one for X-ray photoelectron spectrometers on their own; the latter being applied if no suitable electron gun is available. The system for Auger electron and X-ray photoelectron spectrometers combined has been used regularly to calibrate the Metrology Spectrometer II at NPL and experience shows that this gives an instrumental intensity consistency of 0.4% over 10 years. Evaluations have not previously been reported at this level. The system for Auger electron and X-ray photoelectron spectrometers combined is used here in preference to the system solely for X-ray photoelectron spectrometers since it is more robust to the sample condition and can be used over a wider energy range. These issues, and how observed variations in the instrument intensity response may arise, are explained.     

Backward rescattered photoelectron holography in strong-field ionization

By numerically solving the time-dependent Schr¨odinger equation, we observe a remarkable strong-field interference pattern in the photoelectron momentum distribution of a hydrogen atom ionized by a few-cycles laser pulse. This interference pattern is joined together with the familiar near-forward strong-field photoelectron holographic interference. By applying the strong-field approximation theory, we investigate the formation of this interference pattern, which arises from the interference between the backward rescattered part and the direct part of the tunneling ionized electron wave packet. We demonstrate that this backward rescattered photoelectron holographic interference can also be observed in a more realistic parallel two-color laser field. These results pave a new way to look into the atomic and molecular structure with ultrafast timescale.