Spectroscopy of 85Rb in parallel magnetic field in two step excitation

Saturation spectroscopy based on the nonlinear absorption behaviour of sample can be used to investigate narrow absorption signals comparable to the natural line shapes, which are free of Doppler broadening. Using this technique Zeeman effect in hyperfine levels of rubidium atom(85Rb) in the presence of two laser beams - one for 5 2S1/2 state to 5 2P3/2 state (780.0 nm), the other for the latter to 5 2D5/2 state (775.8 nm)is studied. Small magnetic field splits various hyperfine levels. If the field is parallel to the laser beam then there are two kinds of transitions each corresponding to Δm=+1 or -1. The signals tend to shift from their zero-field positions as the field is increased up to 0.5 mT. With the single 780 nm laser beam signal for F=3 to F=3.2 crossover transition. These characteristics are analysed with additional 775.8 nm pump laser beam. (author)