Preparation of Rydberg states in ultracold Li-7 atoms by using coherent or non-coherent optical excitation

Energy spectra of ultracold Rydberg lithium atoms are discussed. Our technique has been used for the experimental observation of coherent and non-coherent components of two-step excitation in Rydberg states. The high sensitivity of the technique has allowed us to record narrow coherent resonance at 2P-41D. The width of this resonance is 3 times less than width of non-coherent resonance. The coherent resonance is observed when the laser is detuned by ±803.5 MHz from the atomic transition 2P3 2.