We report on the development and application of coherent Rayleigh-Brillouin scattering for the in situ detection of large molecules and nanoparticles. This four wave mixing diagnostic technique relies on the creation of an electrostrictive optical lattice in a medium due to the interaction between polarized particles and the intense electric field gradient created by the optical interference of two intense pulsed laser beams. Though this interaction, we can detect the temperature, pressure, relative density, polarizability and speed of sound of a gas and gas mixture. This diagnostic was already successfully demonstrated in atomic and molecular gaseous environments, where the different gas polarizabilities and pressures were successfully measured. We are currently conducting in situ measurements with large molecules and nanoparticles produced in an arc discharge, the results of which will be presented in this meeting.
We report on the development and application of a new laser diagnostic for the in situ detection of large molecules and nanoparticles. This four wave mixing diagnostic technique relies on the creation of an optical lattice in a medium due to the interaction between polarized particles and intense laser fields. Though this interaction, we can detect the temperature, pressure, relative density, polarizability and speed of sound of a gas and gas mixture. This diagnostic was already successfully demonstrated in atomic and molecular gaseous environments, where the different gas polarizabilities and pressures were successfully measured. We are currently conducting measurements with large molecules and nanoparticles, the results of which will be presented in this meeting.
Analysis of the trapped and untrapped motion of particles, combined with direct numerical simulation of the 1D non-stationary Boltzmann equation, demonstrates that atoms and molecules initially at room temperature can be accelerated to velocities in the 10 to 100 km/s range over distances of 100's microns using an optical lattice. The quantity, final velocity, and velocity/energy spread of the accelerated distribution controlled by tailoring the fluence, duration and frequency chirp of the laser beam that make the lattice, indicating the potential for a compact, versatile, and configurable hyper-thermal accelerator/decelerator. Using similar lattice potentials, differential transport of atomic and molecular species with different polarizability/mass ratios leads towards the possibility of gas mixture separation in short pulses or in hollow fibers. A bulk drift can be induced in a gas by the lattice forces, even when the mean kinetic energy is much greater that the maximum dipole potential of the optical field. In this process the transfer of energy from the slowly traveling optical lattice to the gas is analogous to Landau damping of a plasma wave by charged particles.
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