Egodapitiya K N, Li Sha, Jones R R
Department of Physics, University of Virginia, Charlottesville, Virginia 22904-4714, USA.
Phys Rev Lett. 2014 Mar 14;112(10):103002. doi: 10.1103/PhysRevLett.112.103002. Epub 2014 Mar 12.
We have used picosecond THz pulses to induce transient field-free orientation of OCS molecules. Coherent optical Raman excitation prepares the molecules in rotational superposition states prior to THz irradiation, substantially enhancing the degree of orientation. The time-dependent alignment and orientation are characterized via Coulomb explosion in an intense probe laser. The degree of OCS orientation is an order of magnitude larger than previously observed following THz irradiation and is achieved with a significantly smaller THz field.The field-free orientation level is comparable to that generated using pulsed, two-color laser fields but is obtained with negligible target ionization.
我们已使用皮秒太赫兹脉冲来诱导羰基硫（OCS）分子的瞬态无场取向。在太赫兹辐照之前，相干光学拉曼激发使分子处于旋转叠加态，从而大幅提高了取向程度。通过在强探测激光中的库仑爆炸来表征随时间变化的排列和取向。羰基硫的取向程度比之前太赫兹辐照后观察到的情况大一个数量级，并且是在显著更小的太赫兹场下实现的。无场取向水平与使用脉冲双色激光场产生的水平相当，但实现时目标电离可忽略不计。
