DIAGNOSTICS IN A HIGH-FLOW-RATE (GREATER-THAN-6L MIN-1) HELIUM CAPACITIVELY COUPLED MICROWAVE PLASMA - AQUEOUS VERSUS ORGANIC SOLUTION

A helium capacitively coupled microwave plasma (CMP) with a high plasm a gas flow rate (>6 L min-1) is described. Plasma gas flow rates above 6-8 L min-1 produce a cylindrical-shaped plasma. Diagnostic studies w ere performed. Electronic excitation (T(exc)), rotational (T(rot)), an d ionization-recombination (T(ion) temperatures were determined, along with the electron number density (n(e). T(exc) was calculated from th e slope of the Boltzmann plot with the use of Fe as the thermometric s pecies. Values for T(exc) in aqueous and organic solution were 3430 an d 3450 K, respectively. T(rot) determined with the use of both OH and N2+. With OH, T(rot) values were 1620 and 1660 K for aqueous and organ ic solutions, respectively. If no solution was introduced, a T(rot) va lue of 2350 K was determined with N2+. N2+ also gave T(rot) values of 1900 and 1930 K with aqueous and organic solutions, respectively. The T(rot) values were 6220 and 5610 K with the use Cd and Mg, respectivel y. The n(e) value was on the order of 4 X 10(14) cm-3. Background spec tra and limits of detection are also presented.