Hard X-ray Photoelectron Spectroscopy (HAXPES)

Our PHI QUANTES XPS/HAXPES is the only laboratory-based Hard X-ray Photoelectron Spectrometer in Switzerland (with only few  similar systems installed worldwide). The instrument combines a high-energy  monochromatic Cr-Kα X-ray source (hν = 5.41 KeV) with a conventional low-energy monochromatic Al-Kα X-ray source (hν = 1.48 KeV) for state-of-the-art investigations of the chemistry and electronic structure of functional thin films, mutlilayers and their buried interfaces. The XPS/HAXPES chamber is coupled to UHV facilities for in-situ thin-film deposition (with stress monitoring), processing (e.g. thermal annealing, oxidation, reduction), as well as to a glovebox for (electro)chemical surface treatments (e.g. electrochemical functionalizing, etching, anodizing)

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(a) Normalized intensity of zero-loss photoelectrons detected from atoms at depth z beneath the surface in a homogeneous inorganic solid at a detection angle of 45°. The trend is shown for typical values of the inelastic mean free path (λ) of the photoelectrons emitted using soft Al-Kα and hard Cr-Kα X-ray sources. (b) Illustration of the larger probing depth for HAXPES, allowing chemical state analysis of thicker films, bulk-like properties and buried interfaces, while minimizing the effects of surface contamination and ion-induced damage during sputtering.

INSTRUMENTAL CAPABILITIES

The hard Cr-Kα X-ray source allows to obtain elemental and chemical information from  roughly three times larger probing depths (up to about 15-20 nm) as compared to conventional XPS (up to about 6 nm): see figure. This opens unique opportunities for probing thicker film structures and buried interfaces, as well as minimizing the effects of surface contamination and ion-induced damage during sputter depth profiling.

Furthermore, the use of hard X-rays in HAXPES provides access to a wealth of deep core-level photoelectron lines and their associated core- core Auger transitions, which are not available by soft X-rays. This allows advanced chemical-state studies on the basis of the so-called Auger parameter, which is highly sensitive to changes in the local chemical environment of the constituents as function of e.g. the growth, processing and/or service conditions.

The PHI Quantes scanning microprobe is a high-throughput lab-based HAXPES/XPS instrument equipped for fully automated analysis of multiple samples placed on a 7x7 cm stage. The monochromatized soft and hard X-ray beams can be focussed to achieve a lateral resolution down to 10 μm and also scanned across the sample surface to define analysis points, areas,  lines and maps. Surface charging during analysis of electrically insulating samples can be compensated by simultaneous electron and ion neutralization. Besides the interconnected glovebox for (electro)chemical surface treatments, a much smaller transportable glove box can be attached to the entry lock for mounting ex-situ samples under an inert gas (without air exposure).

ANALYTICAL AND EXPERIMENTAL CAPABILITIES

Our instrument is the first lab-based HAXPES facility in Switzerland for state-of-the-art chemical-state studies of thin films and their buried interfaces, offering unique analytical and experimental capabilities, such as:

  • A much-increased attenuation length of detected photoelectrons from shallow core levels, thus allowing non-destructive analysis of the chemistry and electronic structure of thin films and their buried interfaces up to depths of about 10 - 20 nm.
  • Access to deep core-level photoelectron lines and deep-core-level Auger transitions, which are not accessible by conventional lab-based XPS systems, allowing cutting-edge chemical-state studies of functional thin films, catalysts and other types of functional nanomaterials.
  • Capability to separate commonly-overlapping photoelectron and Auger lines by employing much higher incident photon energies, thereby facilitating chemical-state and quantitative XPS analysis of complex multi-element compounds.
  • Extended capabilities for non-destructive quantitative XPS analysis of e.g. the composition, thickness, chemical state of thin films, catalysts and other nanomaterial systems.
  • Versatile experimental capabilities for in-situ thin-film growth (by magnetron sputtering; with in-situ stress monitoring), post-processing (e.g. thermal annealing, oxidation, reduction), electrochemical surface functionalizing (e.g. passivation, anodizing, chemical etching).

TYPICAL ANALYTICAL SERVICES

  • Quantification of the composition, chemical state and thickness of thin films, multilayers and functional surface coatings with a lateral resolution down to 10 micrometer.
  • Investigations of the chemistry and electronic structure at buried interfaces, nondestructively up to a probing depth of about 10 nm, as well as destructively by sputtering up to probing depth in the submicrometer range.
  • Investigation of the chemical bonding state of secondary nano-phase(s) dispersed in a solid matrix, as well as of core-shell nanostructures.
  • Employing different photon energies to resolve commonly overlapping photoelectron and Auger lines for chemical-state and quantitative XPS analysis of complex multi-element compounds, such as catalysts.

SELECTED PUBLICATIONS

  • S. Siol, J. Mann, J. Newman, T. Miyayama, K. Watanabe, P. Schmutz, C. Cancellieri, L.P.H. Jeurgens, Concepts for chemical state analysis at constant probing depth by lab-based XPS/HAXPES combining soft and hard X-ray sources, Surface & Interface Analysis (2020) 1–9 [DOI: 10.1002/sia.6790].
  • A. Beni, N. Ott, M. Pawelkiewicz, M. Wardé, K. Young, B. Bauer, P. Rajput, B. Detlefs, J. Zegenhagen, R. McGrath, M-G Barthés-Labrousse, L.P.H. Jeurgens, P. Schmutz, Hard X –Ray Photoelectron Spectroscopy (HAXPES) characterisation of electrochemical passivation oxide layers on Al-Cr-Fe Complex Metallic Alloys (CMAs), Electrochemistry Communications 46 (2014) 13-17 [DOI: 10.1016/j.elecom.2014.05.024].
Your contacts
Dr. Claudia Cancellieri

Dr. Claudia Cancellieri
Principal Scientist

Telefon: +41 58 765 4324
claudia.cancellieri@empa.ch

 

Dr. Roland Hauert

Dr. Roland Hauert
Senior Scientist

Telefon: +41 58 765 4558
roland.hauert@empa.ch

 

Dr. Lars Jeurgens
Head of the Laboratory

Phone: +41 58 765 40 53

HAXPES, XPS, Hard X-Ray Photoelectron Spectroscopy, Quantes, buried interface, chemical state, Auger Parameter, lab-based HAXPES spectrometer, probing depth, ion beam damage, attenuation length
HAXPES, XPS, Hard X-Ray Photoelectron Spectroscopy, Quantes, buried interface, chemical state, Auger Parameter, lab-based HAXPES spectrometer, probing depth, ion beam damage, attenuation length
HAXPES, XPS, Hard X-Ray Photoelectron Spectroscopy, Quantes, buried interface, chemical state, Auger Parameter, lab-based HAXPES spectrometer, probing depth, ion beam damage, attenuation length
HAXPES, XPS, Hard X-Ray Photoelectron Spectroscopy, Quantes, buried interface, chemical state, Auger Parameter, lab-based HAXPES spectrometer, probing depth, ion beam damage, attenuation length
HAXPES, XPS, Hard X-Ray Photoelectron Spectroscopy, Quantes, buried interface, chemical state, Auger Parameter, lab-based HAXPES spectrometer, probing depth, ion beam damage, attenuation length