(color online) Time-response curves of DPC and DBC: (a) the short-delay time curves of DPC from 0 ps to 6 ps, (b) the long-delay time curves of DPC from 6 ps to 1000 ps, (c) the short-delay time curves of DBC from 0 ps to 6 ps, (d) the long-delay time curves of DBC from 6 ps to 1000 ps. The colored circles represent the experimental data and the corresponding colored solid lines represent theoretical fitting.