PLASMA GENERATION IN AN ORGANIC MOLECULAR GAS BY AN ULTRAVIOLET-LASER PULSE

Plasmas are generated in a low ionization potential gas, tetrakis(dimethylamino)ethylene (TMAE) vapor through a one-photon ionization process by an ultraviolet laser beam at a 193 nm wavelength. The TMAE plasma characteristics are studied by means of a Langmuir probe and microwave scattering. A new method is used to measure the 193 nm ultraviolet (UV) photon absorption cross section in TMAE. It is determined to be 1.1+/-0.3X10(-17) cm2 from the axial profile of electron density. The temporal evolution of electron temperature is measured. A peak electron density of n(e)=5X10(10(13)/cm3 and peak electron temperature of T(e)=1 eV are measured at 500 mTorr TMAE pressure. The plasma decay process is studied, and the electron-ion recombination coefficient is measured to be 5.4+/-0.5X10(-6) cm3/s. A theoretical model is derived to describe the photon flux and the one photon ionization process. An application of a TMAE plasma as a mirror for microwave reflections is proposed.