Mass Spectrometer: Time of Flight Secondary Ion (ToF SIMS) - 1997
Quick Specs
- Mass Range: 0-10,000 amu
- Mass Resolution: 9000 or greater
- Spatial Resolution: 0.12 μm
- Ion guns: 0.5 to 11 kV Cs & 0.5 to 25 kV Ga
- Ion Sputtering Rate: Cesium Source, 1 nm/s
The Physical Electronics Instruments (PHI) Model T2100 time-of-flight secondary ion mass spectrometer (TOF-SIMS) is used to perform research activities such as:
- Identifying organic overlayers or contamination spots or layers on diverse surfaces ranging from mineral grains to silicon chips
- Simultaneous mapping of the surface distribution of elements or molecules within an area of 10 x 10 to 400 x 400 microns or more, often in combination with identifying elements or molecules
- Identifying depth distribution of elements within materials such as thin films or in particles deposited on a substrate
- Mapping of isotopically labeled species (e.g., bacteria in soils).
The instrument uses a pulsed and focused ion source and time-of-flight analyzer to obtain high spatial and mass resolution data from a sample surface. This system is particularly good at examining organic materials due to its high mass resolution and range capabilities. Most data are collected in a "static" mode with minimal damage to the outer surface of the sample. A second ion source is used for higher rate sputtering.
Features and capabilities of the TOF-SIMS include:
- A focused gallium ion beam (0.12 μm to 2.0 μm, 1.5 nA)
- A beam raster to allow data collection and imaging to 700-mm diameter in size
- Scanning electron microscope imaging of the sample
- Mapping
- Compatibility with the EMSL Sample Transfer System
- A charge-coupled device camera with imaging capability down to 3 μm
- A cesium ion source for both pulsed and DC sputtering (230 nA, 2 mm)
- A charge compensation source - pulsed low-energy electron gun
- A cold stage with the capability for introducing frozen samples.
Performance Specifications
| Time-of-Flight Analyzer | |
|---|---|
| Mass Analyzer | A PHI TRIFT II energy-compensating TOF mass spectrometer that uses three spherical electrostatic analyzers. The spectrometer has a 2-m normal flight path. |
| Detector Optics | Dual microchannel plates with a phosphor screen. A video camera provides real-time viewing of secondary ions. |
| Detector Electronics | 1024-stop Time-to-Digital converter with 138-ps minimum time resolution. Includes a preamplifier and a proprietary constant fraction discriminator for enhanced precision in the measurement of the time of flight. |
| Analyzer Control Electronics | Bipolar supply for the focusing and steering elements. Extraction voltage pulsed to the ground to provide a field-free region at the sample during charge neutralization. |
| Detector Supply | Channel plate multiplier supply with post-acceleration bias supply with integrated pulsing and bunching |
| Beam Energy | 0.5-25 keV; 15 and 25 keV nominal operating voltages |
| Maximum Beam Current | > 1.5 nA |
| Minimum Beam Diameter | < 120 nm pulsed < 2 mm bunched |
| Pulse Width | < 700 ps bunched |
| Pulsed Cesium Primary Ion Beam | |
| Source Type | Surface ionization source producing monoisotopic 133Cs. |
| Beam Energy | 1 to 11 keV |
| Maximum Beam Current | 10 nA |
| Pulsed Charge Neutralizer and Electronic | |
| Type | Low energy (< 20 eV) pulsed, focused electron gun. The sample voltage is at ground potential during charge compensation. Repetition rate, pulse duration, and sample pulsing are under computer control. |
| Sample Handling | |
| Stage | x and y axis manipulators with ±2.5 cm translation |
| Sample Holder | Accepts 5 cm x 5 cm x 1 cm mounts with front referencing |
| Sample Viewing | |
| Viewing Optics | Microscope and color video camera |
| Ion Beam Imaging | Ion-induced secondary electron detector and secondary ion mapping |
| Image Capture | Full color viewing and archiving of sample images |
| Single Sample Cooling Stage | |
| Cooling | Liquid nitrogen dewar on the sample stage |
| Temperature | < -120°C |
| Specimen Holder | High thermal efficiency, 25-mm diameter |
Sample Preparation and Handling
The TOF-SIMS is equipped to handle both the standard PHI holder for the T2100 model and the EMSL sample platens. The standard PHI holder comes in several different configurations and can hold samples up to 2 in x 2 in x 0.5 in. Almost any vacuum-compatible sample that fits within the x-y dimensions of the holder and that is less than 0.5-in thick can be analyzed using this instrument.
The EMSL sample platen can hold samples up to 2 in in diameter with thicknesses less than 1 in, although smaller samples are preferred. This holder interconnects with the EMSL Sample Transfer System and allows samples to be prepared and altered in several unique ways, including by electrochemical and liquid exposure, plasma treatment, coating deposition, optical exposure, and processing by heating and cooling.
The laboratory where the instrument is housed is equipped with a variety of ways to cut, polish, and clean samples prior to analysis or experiment. All work with the TOF-SIMS and in the associated laboratory must be performed in compliance with EMSL practices and permits.
Users typically do not acquire the expertise necessary for hands-on use of this instrument and difficult data interpretation without multiple visits and training sessions. Therefore, hands-on operation of the TOF-SIMS is limited to a small number of trained users. However, a trained operator is available to assist users in both data acqusition and interpretation.
All Related Publications Related Publications
- Chemical Speciation of Sulfur in Marine Cloud Droplets and Particles: Analysis of Individual Particles from the Marine Boundary Layer Over the California Current.
- Reactive Landing of Peptide Ions on Self-Assembled Monolayer Surfaces: A Alternative Approach for Covalent Immobilization of Peptides on Surfaces.
- Soft-Landing of Peptide IOns Onto Self-Assembled Monolayer Surfaces: an Overview.
- Characterization Challenges for Nanomaterials.
- Micro-Raman and Micro-Infrared Spectroscopic Studies of Pb- and Au-Irradiated ZrSiO4: Optical Properties, Structural Damage and Amorphization .
