Figure 3

The azimuthal angle ϕ of the P-branch (solid diamonds) and R-branch (solid circles) lines generated at the pump-probe time delay of 1.5 ps as the functions of the angle .

The azimuthal angle of the seed pulses (equivalent to the angle here) measured in the wavelength range of 397–410 nm (i.e., the spectral range where the laser lines are excluded) as a function of the angle is presented with the black dashed line, showing a linear polarization unaffected by the aligned molecules. For comparison, same measurements on the azimuthal angles ϕ of the P-branch and R-branch lines generated at a pump-probe time delay of 3.3 ps are shown with the open diamonds and open circles, respectively.