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State of the art hemispherical energy analyzer with MCD-9 detector for photoelectron spectroscopy measurements (XPS and UPS) in the pressure regime from UHV to near ambient pressure (NAP)

The PHOIBOS 150 NAP Analyzer is a true 180° hemispherical energy analyzer with 150 mm mean radius. It consists of a differentially pumped electrostatic pre-lens, with a three-stage differentially pumped PHOIBOS 150 analyzer. Thus, the design concept provides four separate pressure stages separated by apertures. The first pumping stage (pre-lens) is separated from the analytic chamber by a nozzle with a customizable opening at the tip with diameters between 0.3 mm and 1 mm. By using a turbopump on the pre-lens stage, a pressure difference of four orders of magnitude (compared to the analysis chamber) can be achieved.The first and second stages are separated by an aperture. An in-lens gate valve allows a high-vacuum seal between of the PHOIBOS 150 Analyzer and NAP pre-lens and enables venting of the analysis chamber and pre-lens without venting the energy analyzer.

For Imaging NAP-XPS the pre-lens can be equipped with the SPECS NAP-XPS Imaging Lens Module that supports two different operation modes, one optimized for lateral resolution and one for transmission. In the lateral resolving mode the acceptance angle can be freely adjusted between +/- 3° to +/- 8° giving an ultimate lateral resolution of better than 10 µm with an acceptance area of 0.6 mm in diameter.


  • Wide Angle Pre-Lens with 44 ° Acceptance Angle
  • Near Ambient Working Pressures up to 100 mbar (depending on configuration)
  • Large pass energy range
  • Working range up to 3.5 keV (upgradable to 7 keV with corresponding power supply and detector)
  • High energy and angular resolution
  • High spatial resolution with imaging lens module
  • Ultimate flexibility by switching between high transmission and high lateral resolution mode
  • Fast detectors with high dynamic range for fast real time data acquisition in snapshot mode
  • Pneumatic in-lens gate valve
  • 4 differential pumping stages
  • Full detector flexibility (MCD, 1D-DLD, 2D-DLD, 2D-CCD, 2D-CMOS)

R&D100 in 2010
The PHOIBOS 150 NAP Analyzer won the R&D 100 award for the best 100 products developed in 2010.




Energy Dispersion



8 Entrance, 3 Exit slits and Iris aperture

Magnetic Shielding

Double µ-Metal Shielding

Lens Modes

Angular Resolving and Transmission Lens Modes

Kinetic Energy Range

0 - 3500 eV

Pass Energies

0 - 550 eV continously adjustable


MCD-9 Detector

Measurement Modes

Snapshot mode, Sweeping mode, Fixed energy mode

Energy Window

13% of Pass Energy

Electric Isolation

up to 7 keV


HSA 3500 plus HT 100 for analyzer and HSA 3500 plus HT 173 for pre-lens

Working Pressure

up to 30 mbar (higher pressure values achievable with corresponding nozzle diameters and differential pumping packages)

Acceptance Angle


Angular Resolution

only with 2D detector

Energy Resolution

< 50 meV

Lateral Resolution

only with 2D detector

Smallest Acceptance Spot

Without imaging lens module the smallest acceptance spot is defined by the excitation spot of X-ray source or nozzle diameter

Detector Channels


XPS Count Rates UHV

70 kcps (guaranteed), 150 kcps (achievable) *

XPS Count Rates 10 mbar

7 kcps (guaranteed), 15 kcps (achievable) *

XPS Count Rates 25 mbar

0.5 kcps (guaranteed), 1.5 kcps (achievable) *


* Ag 3d, FWHM < 0.85 eV, small spot monochromated X-ray source µ-FOCUS 600, Al Kα anode, 20 W, Spot size < 250 µm

Mounting Flange

DN150 CF (8" OD)

Working Distance

300 - 500 µm (for standard nozzle with 300 µm diameter)





  1. (2021) A comparative study of electrochemical cells for in situ x-ray spectroscopies in the soft and tender x-ray range

    n situ x-ray spectroscopies offer a powerful way to understand the electronic structure of the electrode–electrolyte interface under operating conditions. However, most x-ray techniques require vacuum, making it necessary to design spectro-electrochemical cells with a delicate interface to the wet electrochemical environment. The design of the cell often dictates what measurements can be done and which electrochemical processes can be studied. Hence, it is important to pick the right spectro-electrochemical cell for the process of interest. To facilitate this choice, and to highlight the challenges in cell design, we critically review four recent, successful cell designs. Using several case studies, we investigate the opportunities and limitations that arise in practical experiments.

    J.-J. Velasco-Vélez, L. J. Falling, D. Bernsmeier, M. J Sear, P. C. J. Clark, T.-S. Chan, E. Stotz, M. Hävecker, R. Kraehnert, and A. Knop-Gericke
    Juan-Jesús Velasco-Vélez et al 2021 J. Phys. D: Appl. Phys. 54 124003
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  2. (2021) In situ investigation of the bismuth vanadate/potassium phosphate interface reveals morphological and composition dependent light-induced surface reactions

    Bismuth vanadate (BiVO4) is an established n-type oxide semiconductor for photoelectrochemical oxygen evolution. Direct charge carrier recombination at the solid/liquid interface is a major cause of efficiency loss in BiVO4-based devices. Intrinsic and extrinsic surface states (SSs) can act as electron and hole traps that enhance the recombination rate and lower the faradaic efficiency. In this study, we investigate the BiVO4/aqueous KPi interface using two types of samples. The samples were prepared at two different deposition and annealing temperatures (450 °C and 500 °C) leading to different morphologies and stoichiometries for the two samples. Both samples exhibit SSs in the dark that are passivated under illumination. In situ ambient pressure hard x-ray photoelectron spectroscopy experiments performed under front illumination conditions reveal the formation of a bismuth phosphate (BiPO4) surface layer for the sample annealed at 450 °C, whereas the sample annealed at 500 °C exhibits band flattening without the formation of BiPO4. These results imply that the light-induced formation of BiPO4 may not be responsible for SS passivation. Our study also suggests that slight differences in the synthesis parameters lead to significant changes in the surface stoichiometry and morphology, with drastic effects on the physical-chemical properties of the BiVO4/electrolyte interface. These differences may have important consequences for device characteristics such as long-term stability.

    M. Favaro, I.Y. Ahmet, P. C. J. Clark, F. F. Abdi, M. J. Sear, R. van de Krol, and D. E. Starr
    Marco Favaro et al 2021 J. Phys. D: Appl. Phys. 54 164001
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  3. (2019) New Insight into the Gas-Sensing Properties of CuOx Nanowires by Near-Ambient Pressure XPS

    This article presents an investigation of the sensing properties of chemiresistors based on Cu2O/CuO core–shell nanowires containing p–p′ heterojunctions. The nanowires were synthesized by a conventional hydrothermal method and used for the detection of ethanol and nitrogen dioxide, reducing and oxidizing agents, respectively. To unravel the chemical processes connected with gas detection, an in situ approach was applied. This approach was based on near-ambient pressure X-ray photoelectron spectroscopy combined with simultaneous monitoring of sensor responses. The in situ measurements were performed during exposure to the analytes at a total pressure of 0.05–1.05 mbar and 450 K and were correlated with chemiresistor response measurements carried out at a standard pressure and under an ambient atmosphere. The study revealed that heterojunction treatment with ethanol vapors, accompanied by partial reduction of the nanowires, is the key step to obtaining chemiresistors with good sensing performance. While the untreated heterojunctions exhibited poor n-type sensing responses, the treated ones showed significantly improved p-type responses. The treated sensors were characterized by a stable baseline, high reversibility, detection limits estimated as 50 ppm for ethanol and 100 ppb for nitrogen dioxide, and with response times in tens of seconds. In all cases, we propose a band scheme of Cu2O/CuO heterojunctions and a gas-sensing mechanism.

    P. Hozák, M. Vorokhta, I. Khalakhan, K. Jarkovská, K. Jarkovská
    J. Cibulková, P. Fitl, J. Vlček, J. Fara, D. Tomeček, M. Novotný, M. Vorokhta, J. Lančok, I. Matolínová, and M. Vrňata
    J. Phys. Chem. C 2019, 123, 49, 29739–29749
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  4. (2018) Electrifying model catalysts for understanding electrocatalytic reactions in liquid electrolytes

    Electrocatalysis is at the heart of our future transition to a renewable energy system. Most energy storage and conversion technologies for renewables rely on electrocatalytic processes and, with increasing availability of cheap electrical energy from renewables, chemical production will witness electrification in the near future1,2,3. However, our fundamental understanding of electrocatalysis lags behind the field of classical heterogeneous catalysis that has been the dominating chemical technology for a long time. Here, we describe a new strategy to advance fundamental studies on electrocatalytic materials. We propose to ‘electrify’ complex oxide-based model catalysts made by surface science methods to explore electrocatalytic reactions in liquid electrolytes. We demonstrate the feasibility of this concept by transferring an atomically defined platinum/cobalt oxide model catalyst into the electrochemical environment while preserving its atomic surface structure. Using this approach, we explore particle size effects and identify hitherto unknown metal–support interactions that stabilize oxidized platinum at the nanoparticle interface. The metal–support interactions open a new synergistic reaction pathway that involves both metallic and oxidized platinum. Our results illustrate the potential of the concept, which makes available a systematic approach to build atomically defined model electrodes for fundamental electrocatalytic studies.

    F. Faisal, C.Stumm, M. Bertram, F. Waidhas, Y. Lykhach, S.Cherevko, F. Xiang, M. Ammon,
    M. Vorokhta, B. Šmíd, T. Skála, N. Tsud, A. Neitzel, K. Beranová, K. C. Prince, S. Geiger,
    O. Kasian, T. Wähler, R. Schuster, M. A. Schneider, V. Matolín, K. J. J.
    Nature Materials volume 17, pages 592–598 (2018)
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  5. (2018) Investigation of gas sensing mechanism of SnO2 based chemiresistor using near ambient pressure XPS

    In this article, we present the results of an investigation into chemical processes which take place at the surface of SnO2-based chemiresistor in various atmospheres (1 mbar of argon, 1 mbar of oxygen, 0.1 mbar of ethanol, 1 mbar of oxygen + 0.1 mbar of ethanol mixture) at common working temperatures (450 and 573 K). The key method for nanoscale analysis was the Near Ambient Pressure X-ray Photoelectron Spectroscopy. In parallel the resistance and DC-responses of SnO2 layer were in-situ monitored providing information about macroscale processes during gas sensing. The change in the sensor resistance after exposure to the ethanol-containing atmospheres together with the disappearance of the band bending effect and observation of different carbonaceous groups including ethoxy groups and acetaldehyde molecules on the sensor surface in the XPS spectra supported the theory of chemical interaction of ethanol with the chemisorbed oxygen. The NAP-XPS spectra also showed that the nanostructured tin oxide is partially reduced even after being exposed to pure oxygen at 573 K. Exposing this surface to the mixture of O2/EtOH did not significantly increase the surface reduction probably due to slow kinetics of the ethanol reduction process and fast kinetics of the oxygen re-oxidation process. However, it was demonstrated that the surface of sensor is slowly getting contaminated by carbon.

    M. Vorokhta, I. Khalakhan, M. Vondráček, D. Tomeček, M. Vorokhta, E. Marešová, J. Nováková, J. Vlček, P. Fitl, M. Novotný, P. Hozák, J. Lančok, M. Vrňata, I. Matolínová, and V. Matolín
    Surface Science, Volume 677, November 2018, Pages 284-290
    Read more
  6. (2005) Electron Spectroscopy of Aqueous Solution Interfaces Reveals Surface Enhancement of Halides

    It has been suggested that enhanced anion concentrations at the liquid/vapor interface of airborne saline droplets are important to aerosol reactions in the atmosphere. We report ionic concentrations in the surface of such solutions. Using x-ray photoelectron spectroscopy operating at near ambient pressure, we have measured the composition of the liquid/vapor interface for deliquesced samples of potassium bromide and potassium iodide. In both cases, the surface composition of the saturated solution is enhanced in the halide anion compared with the bulk of the solution. The enhancement of anion concentration is more dramatic for the larger, more polarizable iodide anion. By varying photoelectron kinetic energies, we have obtained depth profiles of the liquid/vapor interface. Our results are in good qualitative agreement with classical molecular dynamics simulations. Quantitative comparison between the experiments and the simulations indicates that the experimental results exhibit more interface enhancement than predicted theoretically.

    S. Ghosal, J. C. Hemminger, H. Bluhm, B. S. Mun, E. L. D. Hebenstreit, G. Ketteler, D. F. Ogletree, F. G. Requejo, M. Salmeron
    Science 307, pp. 563 - 566
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  7. (2005) High-Pressure X-ray photoelectron spectroscopy of palladium model hydrogenation catalysts. Part 1: Effect of gas ambient and temperature

    In light of accumulating evidence highlighting the major effect of operational conditions (gas composition, pressure, temperature) on the surface/bulk structure of catalytic materials, their characterization should involve more and more in situ methods. We constructed a synchrotron-based high-pressure X-ray photoelectron spectroscopic (XPS) instrument, allowing us to investigate the surface and near-surface state of a catalyst in the mbar pressure range. We discuss here the surface characteristics of palladium samples as a function of gas phase (hydrogen, oxygen) and temperature. We demonstrate that the surface region of catalytic materials behaves dynamically in its composition, always reflecting its environment. For example, surface oxide can be formed on Pd(111) in oxygen, which decomposes rapidly when the gas supply is switched off. The chemical nature of carbonaceous deposits also depends strongly on the operational conditions (gas-phase hydrogen, temperature). This is the first time that an XPS investigation of palladium β-hydride was performed at RT. The possible drawbacks of using a non-UHV setup (e.g., fast carbon accumulation) are also discussed.

    D. Teschner, A. Pestryakov, E. Kleimenov, M. Hävecker, H. Bluhm, H. Sauer, A. Knop-Gericke, R. Schlögl
    Journal of Catalysis 230, pp. 186 - 194
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  8. (2005) In Situ Spectroscopic Study of the Oxidation and Reduction of Pd(111)

    Using a photoemission spectroscometer that operates close to ambient conditions of pressure and temperature we have determined the Pd−O phase diagram and the kinetic parameters of phase transformations. We found that on the (111) surface oxidation proceeds by formation of stable and metastable structures. As the chemical potential of O2 increases chemisorbed oxygen forms followed by a thin surface oxide. Bulk oxidation is a two-step process that starts with the metastable growth of the surface oxide into the bulk, followed by a first-order transformation to PdO.

    G. Ketteler, D. F. Ogletree, H. Bluhm, H. Liu, E. L. D. Hebenstreit, M. Salmeron
    J. Am. Chem. Soc. 127 (51), pp. 18269–18273
    Read more
  9. (2005) Soft X-ray microscopy and spectroscopy at the molecular environmental science beamline at the Advanced Light Source

    We present examples of the application of synchrotron-based spectroscopies and microscopies to environmentally relevant samples. The experiments were performed at the molecular environmental science beamline (11.0.2) at the Advanced Light Source, Lawrence Berkeley National Laboratory. Examples range from the study of water monolayers on Pt(1 1 1) single crystal surfaces using X-ray emission spectroscopy and the examination of alkali halide solution/water vapor interfaces using ambient pressure photoemission spectroscopy, to the investigation of actinides, river water biofilms, Al-containing colloids and mineral–bacteria suspensions using scanning transmission X-ray spectromicroscopy. The results of our experiments show that spectroscopy and microscopy in the soft X-ray energy range are excellent tools for the investigation of environmentally relevant samples under realistic conditions, i.e., with water or water vapor present at ambient temperature.

    H. Bluhm, K. Andersson, T. Araki, K. Benzerara, G. E. Brown, J. J. Dynes, S. Ghosal, M. K. Gilles, H.-Ch. Hansen, J. C. Hemmingerf, A. P. Hitchcock, G. Ketteler, A. L. D. Kilcoyne , E. Kneedler , J.R . Lawrence , G. G. Leppard , J. Majzlam , B. S. Munl, S
    Journal of Electron Spectroscopy and Related Phenomena 150, pp. 86-104
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  10. (2005) XPS investigations of VPO catalysts under reaction Conditions

    The surface of vanadium phosphorus oxide (VPO) catalysts was investigated by (in situ) X-ray photoelectron spectroscopy (XPS) under reaction conditions. Two differently prepared VPO samples with similar catalytic activities showed different spectral behaviour while the catalytic conditions were changed. The vanadium surface oxidation state of both catalysts was found to have the same value close to 4 under reaction conditions, while the oxidation state of vanadium in deeper layers differed significantly. The experimental results suggest that in VPO the catalytically active species located in the topmost surface layers (up to 1 nm depth) are only weakly related to the structure of deeper layers. Based on our results we suggest that the deeper layers act as a substrate material only and can be different from the surface.

    E. Kleimenov, H. Bluhm, M. Hävecker, A. Knop-Gericke, A. Pestryakov, D. Teschner, J. A. Lopez-Sanchez, J. K Bartley, G. J. Hutchings, R. Schlögl
    Surface Science 575 (1-2), pp. 181-188
    Read more


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