Efficient enhancement of field-free molecular orientation by combining terahertz few-cycle pulses and rovibrational pre-excitation

We present a theoretical scenario used for enhancing the degree of field-free orientation for the HF molecule with a moderate permanent dipole moment by using a combination of terahertz few-cycle pulses and rovibrational pre-excitation. An efficient field-free orientation and an obvious enhancement can be achieved by using this scenario even at room temperatures. This scenario can enhance the feasibility of the experimental realization of the sufficient field-free orientation under the present experimental condition in which the intense terahertz few-cycle pulses are available, providing a new way for controlling molecular orientation.