Diagnostics and analyses of decay process in laser produced tetrakis(dimethyl-amino)ethylene plasma

A large volume (hundreds of cm(3)) plasma is created by a 193 nm laser ioni zing an organic vapor, tetrakis(dimethyl-amino)ethylene (TMAE). The plasma is characterized as high electron density (10(13)-10(12)cm(-3)) and low ele ctron temperature (similar to0.1 eV). To investigate the plasma decay proce sses, a fast Langmuir probe technique is developed, including detailed cons iderations of probe structure, probe surface cleaning, shielding, frequency response of the detection system, physical processes in probe measurement, dummy probe corrections as well as noise analysis. The mechanisms for the plasma decay are studied and a delayed ionization process following the las er pulse is found to be important. This mechanism is also supported by opti cal emission measurements which show that nitrogen enhances the delayed emi ssion from TMAE plasma. A model combining electron-ion recombination and de layed ionization is utilized together with experimental results to order th e terms and calculate the relaxation times for delayed ionization. The rela xation times are longer for lower TMAE pressures and lower electron densiti es. (C) 2001 American Institute of Physics. [DOI: 10.1063/1.1329154].