STATISTICAL-MECHANICS OF AR-2(-COUPLED PLASMA() IN AN INDUCTIVELY)

In the mass spectrum of an argon inductively coupled plasma (ICP), the re is a peak due to the presence of the argon dimer ion, Ar-2(+). Usin g elementary statistical mechanics, an attempt is made to elucidate th e mechanism responsible for this ion's presence in the ICP, The assump tion of local thermodynamic equilibrium (LTE) in the ICP leads to thre e possible mechanisms that could be responsible for the presence of th e argon dimer ion, however, the results of the calculations show that only one of the mechanisms agrees with experiment. The experimental me asurements of the number density ratio of Ar-2(+) to Ar+, against whic h the theoretical values are compared, were taken using inductively co upled plasma mass spectrometry (ICP-MS).