The Air Photoemission System Product Range

Introduction to Air Photoemission

The photoemission in air systems are KP Technology’s newest addition to our large surface analysis range. The APS systems measure the absolute work function of a material by Photoemission in Air, no vacuum required. With an excitation range of 3.3eV to 6.8eV, the APS systems are capable of measuring the absolute work function of metals. With the addition of an SPV and SPS source, the full bands of semiconductors can be measured in one system; no other product can do this. Each APS system comes with our gold-standard Kelvin Probe system, capable of Contact Potential Difference Measurements, backed-up by the APS’ absolute measurements.

When light is incident on a material such as a metal or a semiconductor, the photons may have enough energy to liberate electrons from the surface, a process known as the Photoelectric Effect. Photons having insufficient energy will not liberate electrons, while photons of just enough energy will liberate a few electrons; photons of much more energy than the work function will liberate a lot of electrons. The energy required for electrons to escape the material is termed the work function. By varying the energy of the incoming light, the absolute work function can be established. Based on Fowler’s analysis of photoemission, the square root (cube root for semiconductors) of the photoelectron yield is plotted on a graph versus the incident photon energy.

The properties of many materials are governed by the Density of States (DOS) near the Fermi Level. The Air Photoemission system is capable of probing the DOS by differentiating the detected photoelectron yields by the incident photon energy. The DOS measurement can thus be compared to molecular orbital calculations for the material under investigation.

For more information and definition of terms, please visit our knowledge database.

Air Photoemission Spectroscopy Variants

Our new range of Air Photoemission systems (Patent Protected) offers a number of different setups. All systems perform in a dual mode with absolute Work Function measurements (using photoemission) and high-resolution relative Work Function measurements (using the Scanning Kelvin Probe) in ambient conditions.

Additional options are available to add on 3D mapping of surface potential and sample topography (using Scanning Kelvin Probe), and surface semiconductor/solar cell analysis (using Surface Photovoltage and Surface Photovoltage Spectroscopy)

A full explanation of our Photoemission Technique, theory and system can be found in the in the knowledge database. For the Kelvin Probe Technique please see the Kelvin Probe subsection above.


Model

APS01 - Non Scanning Kelvin Probe + Air Photoemission

APS02 - Scanning Kelvin Probe + Air Photoemission

APS03 - Scanning Kelvin Probe + Air Photoemission + Surface Photovoltage

APS04 - Scanning Kelvin Probe + Air Photoemission + Surface Photovoltage + Surface Photovoltage Spectroscopy

Air Photoemission Spectroscopy Specifications

For information on how the Air Photoemission Spectroscopy Systems works, please see our knowledge databse.
System APS01 APS02 APS03 APS04
Measurement Principle Photoelectric Effect (PE) / Off-null Kelvin Probe (KP) Photoelectric Effect (PE) / Off-null Kelvin Probe (KP) Photoelectric Effect (PE) / Off-null Kelvin Probe (KP) Photoelectric Effect (PE) / Off-null Kelvin Probe (KP)
Energy Range 3.4 eV - 7.0 eV (360 nm - 176 nm) 3.4 eV - 7.0 eV (360 nm - 176 nm) 3.4 eV - 7.0 eV (360 nm - 176 nm) 3.4 eV - 7.0 eV (360 nm - 176 nm)
Repeatability Precision <0.05 eV (PE) / <0.003 eV (KP) <0.05 eV (PE) / <0.003 eV (KP) <0.05 eV (PE) / <0.003 eV (KP) <0.05 eV (PE) / <0.003 eV (KP)
Ultraviolet Lamp Deuterium Lamp Deuterium Lamp Deuterium Lamp Deuterium Lamp
UV Spot Area 4.5 mm diameter 4.5 mm diameter 4.5 mm diameter 4.5 mm diameter
Table Size / Scan Area Single Point 50 x 50 mm (standard) 50 x 50 mm (standard) 50 x 50 mm (standard)
Translation Z axis Motorised X, Y, Z axis Motorised X, Y, Z axis Motorised X, Y, Z axis
Table Size / Scan Area Single Point 50 x 50 mm (standard) 50 x 50 mm (standard) 50 x 50 mm (standard)
Operating Conditions Air or Nitrogen at ambient pressure Air or Nitrogen at ambient pressure Air or Nitrogen at ambient pressure Air or Nitrogen at ambient pressure
Power Requirement 100 - 240 V 100 - 240 V 100 - 240 V 100 - 240 V
Outer Dimensions Light Source: 300 x 300 x 200 mm
Measurement Chamber 500 x 450 x 450 mm
Light Source: 300 x 300 x 200 mm
Measurement Chamber 500 x 450 x 450 mm
Light Source: 300 x 300 x 200 mm
Measurement Chamber 500 x 450 x 450 mm
Light Source: 300 x 300 x 200 mm
Measurement Chamber 500 x 450 x 450 mm
Software APS 8.75 for Windows APS 8.75 for Windows APS 8.75 for Windows APS 8.75 for Windows
Surface Photovoltage Module Not Included Not Included Quartz Tungsten Halogen source Quartz Tungsten Halogen source
Surface Photovoltage
Spectroscopy Module
Not Included Not Included Not Included 400 nm - 1000 nm

Product Overview

Provided here is a brief summary of KP Technology Ltd's product range. Bespoke systems are also available to meet the technical needs of our customers. Click here to learn more.

Knowledge Database

This webpage provides information on the science behind the Kelvin probe and the air photoemission systems, ideas for applications, examples of measurements and some comments on current apparatus available. All have been compiled by Professor Iain D. Baikie, who has extensive experience in these techniques. Click here to learn more.

Brochure & Downloads

Find Application Notes on OLEDs, Solar Cells, Diagnosis of Disease, Photovoltaics and a lot more here. Click here to learn more.

Accessories Overview

KP Technology offers a wide array of modular accessories to complement our systems. These can be applied to any system. Our current accessories include the Surface Photovoltage Spectroscopy (SPS), Surface Photovoltage (SPV), LED Rings and Sample Heaters. Click here to learn more.

Support

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