Effect of Temperature on Alignment of N2 and O2 in Laser Field

In terms of a rigid rotor model, time-dependent Schrödinger equation is solved using the pseudospectral method, and the alignment behaviors of diatomic molecular N2 and O2 are studied in the laser field. The evolution of the field-free rotational wave-packets of the molecules after the laser pulse is discussed. The obtained results show that the alignment parameter of the molecules depends on the temperature. Both N2 and O2 molecules are better aligned at lower temperature, but poorly aligned at higher temperature. The behavior can be attributed to the population of the angular moment in the rotational wave-packet of the molecules at different temperatures.