Stark-induced adiabatic Raman passage for preparing polarized molecules.
Stark-induced adiabatic Raman passage for preparing polarized molecules.
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DOI：
10.1063/1.3599711
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发表时间：
2011-07
期刊：
影响因子：
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通讯作者：
N. Mukherjee;R. Zare
中科院分区：
文献类型：
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作者：
N. Mukherjee;R. Zare
我们提出了一种基于stark诱导绝热拉曼通道（SARP）的方法来制备具有已知取向和排列的振动激发分子，用于未来的动态立体化学研究。该方法利用了由不等强度的延迟但重叠的泵和Stokes脉冲引起的（J， M）态依赖的旋转振动能级的动态Stark位移。在无碰撞的条件下，我们的计算表明，我们可以实现完全的人口转移到H(2)分子在其基电子态的激发振动能级（v > 0）。具体来说，可以利用拉曼跃迁的S(0)分支，利用平行于z轴偏振的可见泵浦和斯托克激光脉冲（单轴π-π拉曼泵浦）从（v = 0, J = 0, M = 0）能级完全转移H(2) （v = 1, J = 2, M = 0）能级制备H(2) （v = 1, J = 2, M = 0）能级。同样，可以使用SARP制备H(2) (v = 1, J = 2, M =±2)，其中左圆极化泵浦和沿z轴传播的右圆极化斯托克斯波（σ（±）-σ（可见）拉曼泵浦）。这种技术需要相位相干的纳秒脉冲，在泵浦脉冲和斯托克斯脉冲之间具有不相等的强度，其中一个比另一个强四倍或更多。为了产生理想的拉曼谐振频率扫频，强脉冲的峰值强度需要达到~16 GW/cm(2)。这些条件可以用持续时间为几纳秒，光能为~12和60mj的红色和绿色激光脉冲在直径~0.25 mm的聚焦光束中实现。此外，使用SARP和355 nm泵浦和具有可获得脉冲能量的近红外Stokes激光器，预测完全的种群转移到v = 4振动水平是可能的。
We propose a method based on Stark-induced adiabatic Raman passage (SARP) for preparing vibrationally excited molecules with known orientation and alignment for future dynamical stereochemistry studies. This method utilizes the (J, M)-state dependent dynamic Stark shifts of rovibrational levels induced by delayed but overlapping pump and Stokes pulses of unequal intensities. Under collision-free conditions, our calculations show that we can achieve complete population transfer to an excited vibrational level (v > 0) of the H(2) molecule in its ground electronic state. Specifically, the H(2) (v = 1, J = 2, M = 0) level can be prepared with complete population transfer from the (v = 0, J = 0, M = 0) level using the S(0) branch of the Raman transition with visible pump and Stoke laser pulses, each polarized parallel to the z axis (uniaxial π-π Raman pumping). Similarly, H(2) (v = 1, J = 2, M = ±2) can be prepared using SARP with a left circularly polarized pump and a right circularly (or vice versa) polarized Stokes wave propagating along the z axis (σ(±)-σ(∓) Raman pumping). This technique requires phase coherent nanosecond pulses with unequal intensity between the pump and the Stokes pulses, one being four or more times greater than the other. A peak intensity of ~16 GW/cm(2) for the stronger pulse is required to generate the desirable sweep of the Raman resonance frequency. These conditions may be fulfilled using red and green laser pulses with the duration of a few nanoseconds and optical energies of ~12 and 60 mJ within a focused beam of diameter ~0.25 mm. Additionally, complete population transfer to the v = 4 vibrational level is predicted to be possible using SARP with a 355-nm pump and a near infrared Stokes laser with accessible pulse energies.