Laser-Induced Incandescence (LII)

Background of the Technique

The laser-induced incandescence (LII) diagnostic is one of several diagnostics that we are using for in situ characterization of nanoparticle synthesis in a background, atmospheric-pressure plasma. LII typically involves heating nanoparticles with a short-pulsed laser, and measuring the induced, spatiotemporal incandescence profiles. The LII diagnostic has been extensively used as a combustion diagnostic to study soot particles in background flame environments.

Applications of LII include in situ measurement of the soot volume fraction and size measurements. Measuring the soot volume fraction involves recording spatially-resolved, planar incandescence profiles. Since regions with higher concentrations of soot particles have brighter incandescence, spatially-resolved measurements of the soot volume fraction can be obtained from planar incandescence measurements. Absolute soot volume fraction measurements can be obtained as well, with appropriate calibration techniques. Particle size measurements are obtained by relating soot diameters to the decay rate of time-resolved LII signals. Since incandescence is a function of particle size and temperature, by numerically calculating the particles’ time-resolved temperature profiles during and after the laser pulse, particle sizes can be extracted from time-resolved LII signals.

Applications for Plasma-Assissted Synthesis

We have used the LII technique to detect and characterize a range of carbon nanomaterials produced using high-pressure, anodic arc discharge. In order to apply the LII heat transfer model to the plasma environment of a carbon arc, we have added plasma processes to the commonly utilized model for flames. Our key result is a detailed measurement of the sizes of largest particles existing at different radial distances from the arc axis. This constitutes the first application of LII to a high-pressure plasma environment.

Immediate Future

Currently, we are working towards the application of LII for characterization of boron nitride nanoparticles and nanotubes synthesized by plasma arc and plasma torch.


Select (non-exhaustive) references:

H.A. Michelsen, Understanding and predicting the temporal response of laser-induced incandescence from carbonaceous particles" , J. Chem. Phys. 118 7012 (2003).

D.R. Snelling et al.,"Determination of the soot absorption function and thermal accommodation coefficient using low-fluence LII in a laminar coflow ethylene diffusion flame" , Combustion and Flame 136 180 (2004).

C. Schulz et al., "Laser-induced incandescence: recent trends and current questions" , Appl. Phys. B, 83 333 (2006).

F. Liu et al.,"Influence of polydisperse distributions of both primary particle and aggregate size on soot temperature in low-fluence LII" Appl. Phys. B, 83 383 (2006).

H.A. Michelsen et al., "Influence of the cumulative effects of multiple laser pulses on laser-induced incandescence signals from soot" Appl. Phys. B, 87 503 (2007).

F. Cignoli et al., "Influence of the bath gas on the condensation of supersaturated iron atom vapour at room temperature" Appl. Phys. B, 96 593 (2009).

H. Bladh et al., "Influence of soot particle aggregation on time-resolved laser-induced incandescence signals", Appl. Phys. B, 104 331 (2011).

T.A. Sipkens et al., "In situ nanoparticle size measurements of gas-borne silicon nanoparticles by time-resolved laser-induced incandescence", Appl. Phys. B, 116 623 (2014).

J.M. Mitrani and M. Shneider., "Time-resolved laser-induced incadesence from multiwalled carbon nanotubes in air", Appl. Phys. Lett, 106 4 (2015).

M.N. Shneider., "Carbon nanoparticles in the radiation field of the stationary arc discharge", Phys. Plasmas 22, 073303 (2015).

S. Yatom et al.,"Detection of nanoparticles in carbon arc discharge with laser-induced incandescence", Carbon 117, 154 (2017).