XPS Spectroscopy Introduction

Electron Spectroscopy in Chemical Analysis (ESCA) is another name for X-Ray Photoelectron Spectroscopy (XPS Spectroscopy). Quantitative atomic composition and chemical composition can be determined with the help of X-Ray Photoelectron Spectroscopy. It samples from the surface to a depth of 50-100 and is hence a surface analysis approach. Sputter depth profiling is another application for XPS spectroscopy. Matrix-level element quantification as a function of depth is a valuable method for characterizing thin films.

The X-ray Photoelectron Spectroscopy is a method for analyzing elements. This is the first time that chemical state information has been provided for the elements that have been found. The separation of sulfate and sulfide sulfur is a useful application. The method involves exposing a sample to a beam of monochromatic X-rays. This causes the release of photoelectrons whose energies are indicative of the elements present in the volume under investigation.

X-rays can reach several microns into a substance and compel electrons to escape. Therefore, the XPS detector can only be reached by electrons with energies above 100 angstroms.In XPS, the photoelectrons emitted from a material that has been subjected to monochromatic X-rays have their kinetic energy quantified. Emitted electron energies are indicative of both the elements present and their bonding or oxidation states. There is a correlation between the number of atoms and the number of electrons released. Although X-rays can travel many millimeters into a material, the photoelectrons they make from direct ionization of the impacting X-rays can only lose a small amount of energy before leaving the surface.

Binding energy, the amount of energy needed to pry an electron loose from its orbital, is different for each element. The X-ray energy (hv), the emitted electron kinetic energy (KE), and the electron binding energy (BE) are all related in the following ways:

The spectrometer’s work function, BE = h-KE- 

The kinetic energy of photoelectrons can be measured, allowing for elemental analysis. Furthermore, the amount of energy shift (chemical shift) at the photoelectron peak position can reveal information such as whether or not an element exists as a compound (and what kind) based on the binding energy of the element and its bonding state (and chemical environment).

The first step in XPS spectroscopy is a survey covering the entire energy range with the maximum possible sensitivity. As a result, we can detect and quantify surface elements. Second, to ascertain the bonding condition, we normally employ high-resolution XPS analysis, which involves narrow scans at higher energy resolution. By analyzing the location and shape of the peak, we can deduce the nature of the chemical bonds. Finally, depth profile analysis helps determine the composition of a thin film since it examines the atomic composition of the film.

To better serve its customers in a wide variety of sectors, Infinita Lab employs X-ray Photoelectron Spectroscopy in a number of contexts. Research and development, process improvement, and problem-solving all fall under this category.

Cross-Phase Shift Spectroscopy Examples

XPS Analysis Case Studies

• The detection of discolourations and stains
• Cleaning Methods: A Characterization
• Examining the make-up of fragments and powders
• Identifying the Sources of Contamination
• Identifying and quantifying surface changes by comparing polymer functionality before and after processing
• Matrix-level constituents and contaminants (down to the low% level) can be detected by obtaining depth profiles of thin film stacks (both conducting and non-conducting).
• Comparing the oxide thickness of various samples
• Monitoring the amount of grease on hard drives

We have a smart Chart for XPS Spectroscopy in our collection. X-ray photoelectron spectroscopy (XPS) is a strong survey analysis technique since it can detect and quantify all elements (except H and He) and offer chemical state information.

Broad-Bandwidth X-Ray Photoelectron Spectroscopy

XPS examines the full energy range from present day except for H and He.

A program that can detect and count the number of elements on a surface.

Ultra-precise X-ray photoelectron spectroscopy (limited energy range)

X-ray photoelectron spectroscopy (XPS) analysis utilizes narrow energy ranges that scan under high-energy resolution settings to provide more specific chemical state information.

It is useful for determining chemical composition by analyzing peak position and shape (usually a survey XPS analysis is performed first to validate the presence of components).

Profile XPS analysis at depth

In this mode, just certain bands of energy are analyzed. The outermost 10–20 nm are studied by tilting the sample for nondestructive depth profiling. The sample is initially inspected with restricted energy ranges, and then it is ion sputtered to remove the necessary amount of material for destructive depth profiling of depths up to a few microns. These two processes are repeated until the maximum XPS analysis depth is reached.

It is useful for determining the relative abundance of different elements at different depths. Chemical states can be identified using nondestructive depth profiling. Since sputtering frequently alters the chemistry, chemical state information is typically unavailable in destructive depth profiling.

Ideal Applications of X-ray Photoelectron Spectroscopy

One is the examination of stains, residues, and organic and inorganic elements on the surface.

Second, extracting surface-based information about chemical composition and state

Third, thin film composition depth profiling

In addition, the thickness of thin films of oxides (SiO2, Al2O3)

The benefits of XPS

• Surface-based chemical-state identification
• All elements besides hydrogen and helium have been identified.
• Comparison of chemical states between samples, as well as other forms of quantitative analysis
• Insulating samples (such as paper, plastics, ceramics, and glass) are among the many materials that can benefit from this method.
• Surface-aware (analysis depth of 1–10 nm)
• Substrate analysis for abundant elements (often > 1 at. %)
• Measuring the Thickness of Oxygen

Constraints of XPS

• Typically, detection limits are below 0.1 percent.
• Minimum measurable analytical area, 30 m
• Very little is known about the long-range bonding of organic compounds.
• A UHV-compatible sample is required.

Specifications for X-ray Photoelectron Spectroscopy

• Detection: photoelectrons from atoms close to the surface
• Sub-monolayer Detection Limits of 0.1-1 at% for the Elements Li-U Chemical Bonding Information
• In profiling mode, the depth resolution is 20-200, whereas in surface analysis mode, it is 10–100.
• Yes, imaging and mapping are possible
• Size of the probe/lateral resolution: 10 m – 2 mm

X-ray photoelectron spectroscopy (XPS) provides information on a sample’s chemical composition, allowing for faster product and process improvements, which in turn shortens production cycles and saves money. Also learn about, High-resolution X-ray Photoelectron Spectroscopy (High Res XPS)