College of Physical Science and Technology, Central China Normal University, Wuhan 430079, China.
J Chem Phys. 2013 Dec 7;139(21):214309. doi: 10.1063/1.4836616.
The rovibrational spectra of the N2-D2O and OC-D2O complexes in the v2 bend region of D2O have been measured in a supersonic slit jet expansion using a rapid-scan tunable diode laser spectrometer. Both a-type and b-type transitions were observed for these two complexes. All transitions are doubled, due to the heavy water tunneling within the complexes. Assuming the tunneling splittings are the same in K(a) = 0 and K(a) = 1, the band origins, all three rotational and several distortion constants of each tunneling state were determined for N2-D2O in the ground and excited vibrational states, and for OC-D2O in the excited vibrational state, respectively. The averaged band origin of OC-D2O is blueshifted by 2.241 cm(-1) from that of the v2 band of the D2O monomer, compared with 1.247 cm(-1) for N2-D2O. The tunneling splitting of N2-D2O in the ground state is 0.16359(28) cm(-1), which is about five times that of OC-D2O. The tunneling splittings decrease by about 26% for N2-D2O and 23% for OC-D2O, respectively, upon excitation of the D2O bending vibration, indicating an increase of the tunneling barrier in the excited vibrational state. The tunneling splittings are found to have a strong dependence on intramolecular vibrational excitation as well as a weak dependence on quantum number K(a).
N2-D2O 和 OC-D2O 复合物在 D2O 的 v2 弯曲区域的 rovibrational 光谱已在超音速狭缝射流膨胀中使用快速扫描可调谐二极管激光光谱仪进行测量。这两个复合物都观察到了 a 型和 b 型跃迁。由于复合物内的重水隧道效应，所有跃迁都加倍了。假设隧道分裂在 K(a) = 0 和 K(a) = 1 时相同，则确定了 N2-D2O 在基态和激发振动态以及 OC-D2O 在激发振动态下每个隧道态的带原点、三个旋转常数和几个变形常数。与 N2-D2O 相比，OC-D2O 的平均带原点向蓝移了 2.241 cm(-1)，与 D2O 单体的 v2 带相比。N2-D2O 在基态的隧道分裂为 0.16359(28) cm(-1)，约为 OC-D2O 的五倍。当激发 D2O 弯曲振动时，N2-D2O 的隧道分裂分别降低约 26%和 OC-D2O 的隧道分裂分别降低约 23%，表明在激发振动态下隧道势垒增加。发现隧道分裂强烈依赖于分子内振动激发，并且对量子数 K(a)的依赖性较弱。
