Preparation and alignment of highly vibrationally excited molecules by CARP – chirped adiabatic Raman passage

Three-dimensional time-dependent Schrödinger equation simulations of Raman excitation of the Cl2 molecule are used to demonstrate the feasibility of efficient high vibrational excitation (v⩾20) of symmetric non-polar bonds using short (ps) chirped frequency laser pulses at intensities below the ionization threshold (I=2×1013 W/cm2). The process called chirped adiabatic Raman passage (CARP) involves sequential Raman excitations Δv=+1 during the pulse accompanied by rotational transitions. It is shown that as a result of CARP, considerable laser alignment of the molecule is achieved in high vibrational levels, thus offering a new tool for the study of dynamics and reactivity of aligned excited molecules.