PULSE System for Dynamic XPS
Whether you want to find and optimise parameters for controlled and reproducible processes or to gain a fundamental understanding of underlying dynamics of reactions at the surface, the SIGMA PULSE is a unique system for real-time experiments and analysis. The cutting-edge instrumentation with the ASPECT analyser and NEO control suite offer unrivalled spectrometer transmission and resolution as well as high-speed spectrometer electronics for fast and time-resolved data acquisition. The PULSE has a compact yet comprehensive design that leaves space to expand the setup with various UV, electron and ion sources for sample preparation for maximum flexibility.The PULSE system offers a unique solution for observing, monitoring and even tailoring surfaces, making it ideal for process control, oxidation, thermal reduction and stability, growth processes, phase transitions and catalytic reaction studies.
The PULSE system provides a handy and versatile platform, it has a flexible design that permits an adaptable setup with a port configuration which is suitable for complex growth experiments involving evaporation sources. The analysis region is mu-metal shielded to remove static magnetic fields. The UHV chamber is evacuated by a turbo pump as standard and can be upgraded with an ion and titanium sublimation pump for a true UHV environment.
Snapshot Acquisition and Dynamic XPS
Within the ASPECT's multi-channel detector multiple stripe anodes are arranged in parallel to acquire a spectroscopic interval simultaneously. This snapshot acquisition forms the basis for Dynamic XPS measurements. Dynamic XPS provides information on the temporal evolution of chemical states and elemental quantities on the millisecond timescale.
In standard configuration the PULSE achieves count rates > 3.5 Mcps (Ag 3d5/2) with 0.6eV energy resolution using the MECS monochromated X-ray source.
A survey spectrum of Ag with a resolution of 1.5 eV (FWHM) at the 3d5/2 peak, acquired in 2 seconds.
Rapid Survey Acquisition for Fast XPS Measurements
High spectrometer sensitivity and fast electronics enable the acquisition of full-scale survey spectra within 2 seconds.
Whether the priority is to prevent sensitive samples from damage due to prolonged X-ray exposure, or simply to save time, the rapid survey acquisition is the perfect tool for fast XPS measurements without compromising the quality of data.
Peak Monitoring for Dynamic XPS
When monitoring multiple spectra at various binding energies, the detected electron energies may be rapidly switched between snapshot acquisitions in milliseconds. Peak Monitoring is the ideal mode for observing dynamic reactions and monitoring surface transformations in real-time for a comprehensive understanding of your surface.
Dynamic XPS colour coded 3D data representation of the Ag Auger, 3p and 3d peak energies versus intensity and time. Each snapshot spectrum is collected sequentially and each collection loop repeated 50x for a combined analysis time of 7 seconds. The spectra can be examined individually (10ms acquisition time) or accumulated over several repetitions (10x10ms acquisition time) as shown.
The thermal reduction of Titanium oxides has been analysed by Dynamic XPS using snapshot acquisition of multiple peaks with the ASPECT analyser. Peak Monitoring was used to measure the spectral changes of O 1s, Ti 2p, C 1s and the valence band. While the sample temperature was ramped from 550K to 900K within two minutes, the oxygen reduction took place within ~1 minute. The data analysis revealed a step-wise process with an initial reduction of the 4+ oxidation state of titanium at intermediate temperatures between 600K and 725K before further reduction of the 3+ oxidation state at temperatures > 725K. Each acquisition cycle took 570 ms, with 500 ms detection time and the analysis was completed within 10 minutes.