Two-colour three-photon excitation of the 6snf 1,3F3and 6snp 1P1, 3P1,2Rydberg levels of Yb I

Abstract

We report a reinvestigation of the 6snf 1,3F3 (9 < or = n < or = 30), 6snp 1P1 (12 < or = n < or = 56), 6snp 3P1 (12 < or = n < or = 21) and 6snp 3P2 (12 < or = n < or = 19) Rydberg states of ytterbium atom using a two-colour three-photon resonant excitation technique through the 4f146s5d 1D2 intermediate level. The spectra were observed using two dye lasers simultaneously pumped by a common Nd:YAG laser in conjunction with a thermionic diode ion detector. Some new levels have been identified in the vicinity of the 6snf (9 < or = n < or = 16) Rydberg levels. Three new perturbers 4f135d 26s3D3 at 48 584.1 cm-1, 4f135d26s 1F3 at 49 122.4 cm-1 and 4f135d26s 3G3 at 49 661.6 cm-1 have been located in addition to observation of the 6s9d 1D2 and 6p2 1D2 even parity levels due to sequential excitation from the 6s6p 1P1 level. The interchannel interactions among the J = 2 and J = 3 channels have been analysed using multichannel quantum defect theory.