Experimental observation of Autler–Townes splitting of the Na 2[formula omitted] mixed levels

Abstract

The Autler–Townes (A–T) splittings of the A 1 Σ u +∼ b 3 Π u mixed levels of Na 2 have been experimentally studied by pulsed laser perturbation facilitated optical–optical double resonance (PFOODR) spectroscopy. A pump laser was used to excite the A 1 Σ u +(v A ′,J ′)∼ b 3 Π u (v b ′,J ′)← X 1 Σ g +(v″,J″=J ′±1) transition and a probe laser was used to probe the A–T splitting of the A 1 Σ u +∼ b 3 Π u mixed levels by further exciting from the intermediate levels to the 2 3 Π g state and monitoring the 2 3 Π g → a 3 Σ u + violet fluorescence. When the pump laser frequency was held fixed to a frequency between the A 1 Σ u +(v A ′,J ′)← X 1 Σ g +(v″,J″=J ′±1) and b 3 Π u (v b ′,J ′)← X 1 Σ g +(v″,J″=J ′±1) transitions, three OODR excitation lines were observed: one line via the A 1 Σ u +(v A ′,J ′) intermediate level, one line via the b 3 Π u (v b ′,J ′) intermediate level, and between these lines, a “ creeper” line via a new superposition intermediate state. The relative intensities of the three lines vs. the detuning of the pump laser frequency, the intensities of the pump and probe lasers and the buffer gas pressure were studied.