Revised_minimum_requirements_4_June_2013.pdf

Requirements /Specifications for the AFIT Electron Spectrometer

Spectrometer:

A hemispherical electron energy analyzer/spectrometer with a mean radius of greater than 100 mm providing an energy resolving power > 1000, i.e., an energy resolution < 3 meV FWHM at 2 ev pass energy and 20 eV kinetic energy is required. This spectrometer must be operable in an ultrahigh vacuum atmosphere at pressures of 10-10 torr, capable of a bakeout temperature of 150oC, and have a DN100CF (6 inch ODCF) flange for mounting to the main vacuum chamber.

It must accommodate an electron energy range of at least 0.5 to 1500 eV, have a transmission mode lens acceptance of +/- 15 degrees, and a pass energy range of 2 – 200eV. The spectrometer must be constructed of non-magnetic materials inside μ-metal shielding and utilize a slit mechanism providing for at least 6 entrance / exit slits which can be set independently from outside the vacuum. Entrance and exit slits should operate independently.

For each pair of entrance slits, one slit defines the energy resolution while the other slit serves to match the angular spread for the analyzer. This arrangement allows optimum transmission for all chosen slit sizes and resolution settings. A view port is to be provided for through the lens (optical) alignment. Fringe field corrections must be provided in the entrance and exit areas to guarantee excellent energy resolution at very low kinetic energies.

A multi-element, two-stage transfer lens with well-defined optical properties must be utilized to provide ultimate transmission of electrons from the source to the analyzer. All lens modes must be able to be set electronically. In addition, a standard working distance of 40 – 45 mm and a 44° conical shape of the front part of the lens should be provided to guarantee optimum access to the sample for all types of excitation sources. An adapter and mu-metal tube should be provided for connection to user’s vacuum chamber.

For small spot analysis, a lateral resolution down to at least 300 μm must be available. In addition, angular resolution must be able to be optimized down to ±0.5° to be accomplished with an Iris aperture in the diffraction plane of the lens system allowing the angular acceptance to be continuously adjusted between ±1° and ±9° while keeping the acceptance area on the sample constant.

Electron Detection:

The detection package should contain an ultra-fast, low-noise preamplifier and counter providing for single channel or multi channel detection. Detection is by a modern 2D low noise digital CCD-MCP detector system with a noise level of < 0.01 cps/channel. Detectors should be able to be retrofitted on site. The detector should preferably be flange-mounted with a standard detector assembly consisting of MCD or CCD channel electron multipliers arranged as a single block providing both compactness and durability. Channel electron multipliers with an extended dynamic range for extremely high count rate applications should be standard.

Upgrades from single to multichannel detection should be capable of being performed on-site.

The design of the detection electronics should take into account the need for reliable counting results even in difficult environments and for extended dynamic ranges.

Performance:

For XPS using the Ag 3d 5/2 or Mg Kα spectral line ,at 15 kV, 300 W, with a distance between sample-anode <15 mm: Provides resolution of 0.85 eV with count rates (signal over noise) of at least 300,000 for SCD, 1,700,000 for MCD of 5 channels, and 3,000,000 for MCD of 9 channels.

For UPS (Ag valence band, He I, (*) Fermi edge width (12 to 88%) at T=300 K): Provides resolution of 140 meV*with S/N count rates of 2,000,000 10,000,000 20,000,000.

For AES using Cu LMM, 20 nA sample current (+15 V bias), 5 keV: Provides resolution of 0.5 %.

For ISS Ag , 0.5 μA sample current (+90 V bias), 2 keV, He+: Provides resolution of .5 %.

Power Supply:

A single power supply providing ultra-stable conditions for reliable accurate measurements is desired. A modular design / architecture is preferable with all detector high voltage modules included. The power supply should be fully digitized, with super low noise modes. The modular design of the unit should allow independent setting of all voltages. The complete electronics package should be contained in a single 19” standard rack housing with removable cables. Both pass energy and retarding ratio should be able to be continuously adjusted to fine-tune resolution and intensity. Real time read out and electronic analyzer lens X/Y deflectors for diagnostic purposes are desired. The power supply must operate on a standard 120v, 60 Hz power line.

Data Acquisition & Processing:

A software package utilizing the Windows operating system and combining ease of operation with powerful data acquisition and analysis routines must be provided. This data acquisition and data processing software must provide computer control of all analysis methods possible with the electron analyzer. Predefined sequence measurements should be limited only by computer memory and disk space. For MCP/CCD detectors, the user has online access to the separate channels and a semi-automatic dispersion calibration should ensure optimal resolution and energy calibration for all analyzer settings. An MCD ratemeter should be included. Standard data processing tools should include background subtraction, satellite subtraction, smoothing, integration, differentiation, numerical operations, scaling, view options, shift, work function adjustment and much more. Peak fitting routines and quantification with easily configurable files for peak parameters (including database for XPS and AES) result in comprehensive surface analysis software for a wide range of applications.

Installation Assistance and Functional Test

Help with mechanical installation at the customer site must be included. Engineer runs functional test showing that the equipment runs at the customer’s site and that nothing has been damaged in transit to the site. Normal time spent at the site would be 2 to 3 days. Travel expenses for the applications engineer are to be included.