Small-particle analysis by laser-induced incandescence

Highlights

The technology offered relates to a method and apparatus for analysis of submicron-sized particles, such as soot, over a wide range of particle concentrations with high temporal and spatial resolution. In particular, improvements in the Laser-Induced Incandescence technique (LII) have been made for improved measurement accuracy by the use of a laser beam of low fluence and/or a good laser energy profile.

The technology uses the fact that the incandescence signal is proportional to the volume of the particles. It also uses the fact that transient cooling is dependent on the specific surface area of the particle, which is related to the diameter of the particle.

Technology transfer

This technology is available for licensing, or for further development through a collaborative research agreement with NRC. The business opportunity may be referred to by its NRC ID: 11236.

Market applications

Applications of this technology include the characterization of metal nanoparticles and ceramic nanoparticles used for monitoring, regulatory compliance, process control production of value-added nanoparticles, and many other applications.

How it works

Small particles pose an important area of interest and concern, particularly for environmental and health reasons. The presence of particulate matter, such as soot particles, in the environment has brought about an increased interest in the development of methods and devices for the determination of particulate concentration and its average sizes. Soot in particular has been the subject of study for measurement.

The emission of soot from engines, power generation facilities, incinerators, or furnaces, for example, represents a loss of useful energy and further is a serious environmental pollutant and a health risk. However, the presence of soot in flames can also have positive effects. For example, the energy transfer from a combustion process is largely facilitated by the radiative heat transfer from soot. Thus, to understand soot formation and develop control strategies for soot emission or formation, measurements of soot concentrations are necessary.

The application of laser-induced incandescence (LII) is used to analyze the characteristics of submicron-sized particles. LII is recognized as a good tool for determining the characteristics of small particles in a gas, e.g., volume fraction, particle size, and specific surface area.

In LII, particles are heated by a pulsed laser light beam to a temperature where incandescence from the particles can be distinguished from ambient light. The temperature of particles and their volume fraction governs the incandescence. The temperature decay rate is proportional to the primary particle size.

An optical arrangement ensures a near-uniform laser energy distribution spatial profile. The use of a low fluence laser beam pulse avoids evaporation of particles. Without significant evaporation and with a uniform energy profile, accurate and precise measurements can be conducted more easily and reliably.

Other applications of the technology include the characterization of metal nanoparticles and ceramic nanoparticles. The characterization can be used for monitoring, regulatory compliance, process control production of value-added nanoparticles, and many other applications. LII is a good diagnostic tool for measurements of particulate as the LII signal is proportional to particle volume fraction and is also related to particle sizes.

Benefits

  • LII signals do not have to be at or near the peak intensity to be measured
  • By avoiding significant particle evaporation, the concentration and primary particle size do not change during the measurement period, enhancing the reliability, ease, precision, and accuracy of the LII technique
  • Measurements can be made throughout the analyzing period until LII signals drop to the noise level of detectors
  • Temperature is measured at many time points to generate the time dependent temperature decay characteristics of the particles being measured

Patents

Contact

To inquire about this technology, please contact:

Martin Rutter, Portfolio Business Advisor
Telephone: 613-990-6439
Email: Martin.Rutter@nrc-cnrc.gc.ca