Knowledge Base

Doublet Separations

• W 4d: 12.5 eV
• W 4f: 2.2. eV
• W 4p: 67.1 eV

The Energies Listed are Binding Energies!

• W 4s: 595 eV
• W 4p: 426 eV
• W 4d: 246 eV
• W 5s: 77 eV
• W 5p: 37 eV
• W 4f: 34 eV
• W 5d: 6 eV

The Energies Listed are Binding Energies!

W is primarily analyzed via the 4f orbital. Due to this low energy, there are many potential overlaps – and as such we have separated these into commonly found, and less-commonly found, – elements.

• F 2s (31 eV)
• Na 2p (31 eV)
• Ti 3p (34 eV)
• K 3s (34 eV)
• W 5p (37 eV)

Full list:

• F 1s (31 eV)
• Na 2p (31 eV)
• Sc 3p (32 eV)
• Sb 4d (32 eV)
• Tm 5p (32 eV)
• Eu 5s (32 eV)
• La 5s (33 eV)
• Nb 4p (34 eV)
• Ti 3p (34 eV)
• K 3s (34 eV)
• Fr 6s (34 eV)
• Mo 4p (35 eV)
• Re 5p (35 eV)
• Gd 5s (36 eV)
• W 5p (37 eV)
• Ta 5p (37 eV)
• Tm MVV (Al source) (38 eV)
• Nd 5s (38 eV)
• V 3p (38 eV)
• Pr 5s (38 eV)
• Sr 4s (38 eV)
• Pm 5s (38 eV)
• Ce 5s (38 eV)
• Hf 5p (38 eV)
• Sm 5s (39 eV)

Energies listed are Kinetic Energies!

W NOO: ~ 176 eV

X-ray photoelectron spectroscopy (XPS) of tungsten is important for several reasons, and it finds application in various fields. Here are some specific examples:

1. Catalysis: XPS is used to study tungsten-based catalysts, such as tungsten oxides and tungsten carbides. These materials are crucial in chemical reactions like hydrodesulfurization, which is used to remove sulfur from fuels.

2. Semiconductors: Tungsten is used in semiconductor devices, and XPS helps in analyzing the surface chemistry and electronic states of tungsten films. This is important for improving the performance and reliability of semiconductor components

3. Coatings and Thin Films: Tungsten coatings are used for their hardness and wear resistance. XPS is employed to investigate the composition and oxidation states of these coatings, ensuring their quality and durability.

4. Corrosion Studies: Tungsten and its alloys are used in environments where corrosion resistance is critical. XPS helps in understanding the surface oxidation and corrosion mechanisms, aiding in the development of more resistant materials

5. Energy Storage: Tungsten oxides are used in energy storage devices like batteries and supercapacitors. XPS provides insights into the chemical states and surface interactions, which are vital for enhancing the efficiency of these devices.

Collection Regions: To ensure a correct background, encompassing both the W 4f, and overlapping W 5p orbitals, it is advised to collect an extended region to higher binding energies, up to approx. 50 eV.

X-ray Induced Reduction: The X-ray beam used in XPS can cause the reduction of tungsten oxides. One study found that after 5 hours of irradiation, an increased reduction of tungsten oxide was observed. The reduction process can change the oxidation state of tungsten, leading to inaccurate analysis if not properly accounted for. For instance, WO3 can be reduced to lower oxidation states like WO2 under X-ray irradiation.(2,3)

Argon Ion Bombardment: In addition to X-ray induced reduction, argon ion bombardment, which is often used for sputtering and cleaning samples, can also reduce tungsten oxides. This is because the energetic Ar+ ions can remove oxygen from the surface, resulting in a lower oxidation state of tungsten. One study used in-situ argon ion bombardment as a reducing agent to obtain lower valency oxidation states of tungsten. For example, Ar+ bombardment of WO2 can lead to the reduction to elemental W(0).(2)

Tungsten metal exhibits an asymmetric lineshape, unlike the various non-conducting oxides. Tungsten disulfide, and tungsten diselenide, however – both being conductive materials, also exhibit a degree of asymmetry in the W 4f region.