State-selective excitation of atoms or molecules in laser pulse fields

The coherent mechanism of ultrafast state-selective excitation of atoms and molecules is presented by a theoretical simulation. To excite a molecule i nto a target vibrational level high-power picosecond pulses are necessary i n the infrared area. This mechanism can be used to excite an atom in the ta rget state by subpicosecond laser pulses in the visible region. Some pulses with different frequencies and powers can be used to reach a target. (C) 1 999 Elsevier Science B.V. All rights reserved.