2-PHOTON OPTOGALVANIC SPECTRA OF ARGON - ODD PARITY RYDBERG STATES

Extensive new data on the odd-parity, single-colour, two-photon optoga lvanic spectra of argon in the visible region is reported using an exc imer-pumped dye laser in conjunction with an argon discharge cell. The experimental technique enables us to record a pure two-photon spectru m in a region which is dominated by one-photon transitions. A large nu mber of two-photon transitions, originating from the two metastable st ates 3p(5)4s[3/2](2) and 3p(5)4s'[1/2](0) to the excited states of con figurations 3p(5)ns (J = 0, 2) and 3p(5)nd (J = 0-4) of argon, has bee n recorded and arranged into 10 Rydberg series. The interchannel inter actions among the 3p(5)(P-2(1/2))nd' and the 3p(5)(P-2(3/2))ns, nd J = 2 channels and the (3)p(5)(P-2(1/2))nd' and the 3p(5)((2)P(3/2)nd J = 3 channels have been studied using the multichannel quantum defect th eory (MQDT). In addition, higher members of the two-photon parity forb idden 3p(5)np series have also been detected.