Communications: Evidence for proton tunneling from the microwave spectrum of the formic acid-propriolic acid dimer.
Communications: Evidence for proton tunneling from the microwave spectrum of the formic acid-propriolic acid dimer.
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通讯：来自甲酸-丙酸二聚体的微波光谱的质子隧道证据。
DOI：
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发表时间：
2010
影响因子：
4.4
通讯作者：
S. Kukolich
中科院分区：
文献类型：
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作者：
A. Daly;P. Bunker;S. Kukolich
使用脉冲束傅里叶变换光谱仪在5-13 GHz范围内测量甲酸-丙酸二聚体的微波光谱。测量了22个正态同位素的a-偶极转动跃迁和3个b-偶极振转跃迁。所有这些观察到的跃迁都被两个酸性质子的协同隧穿效应分裂成双峰。a-偶极跃迁的1-1.5 MHz的较小分裂是由于上隧穿态和下隧穿态的旋转常数的差异。b-偶极跃迁是旋转振动（组合）跃迁，旋转态和隧穿态发生变化，并提供了关于隧穿分裂的直接信息，因为这些观察到的分裂是过渡中涉及的两个旋转态的隧穿能级分裂的总和。b-偶极分裂为55.16（0（00）-1（11））、58.58（1（01）-2（12））和71.24 MHz（2（02）-3（13））。当氘取代氢键质子中的一个或两个时，没有观察到类似的分裂。对于较低的隧穿状态（nu（0）（+）），A=5988.7（7），B=927.782（7），并且C=803.720（7）MHz。对于上隧穿态（nu（0）（-）），A=5988（1），B=927.78（1），并且C=804.06（1）MHz。用一个简单的势函数V=ax（4）-bx（2）的模型，在势垒高度H（e）=3800 cm（-1）时，能很好地再现分裂。
The microwave spectrum of the formic acid-propriolic acid dimer was measured in the 5-13 GHz range using a pulsed-beam, Fourier transform spectrometer. 22 a-dipole rotational transitions and 3 b-dipole rovibrational transitions were measured for the normal isotopomer. All of these observed transitions were split into doublets by the effects of the concerted tunneling of the two acid protons. The smaller splittings of 1-1.5 MHz for the a-dipole transitions are due to the differences in rotational constants for the upper and lower tunneling states. The b-dipole transitions are rovibrational (combination) transitions with a change in rotational state and tunneling state and provide direct information on the tunneling splittings since these observed splittings are the sum of the tunneling level splittings for the two rotational states involved in the transition. The b-dipole splittings are 55.16(0(00)-1(11)), 58.58(1(01)-2(12)), and 71.24 MHz(2(02)-3(13)). No similar splittings were observed when deuterium was substituted for either or both of the hydrogen bonding protons. For the lower tunneling state (nu(0) (+)), A=5988.7(7), B=927.782(7), and C=803.720(7) MHz. For the upper tunneling state (nu(0) (-)), A=5988(1), B=927.78(1), and C=804.06(1) MHz. Using a simple model with potential function V=ax(4)-bx(2) the splittings could be reproduced reasonably well with a barrier height of H(e)=3800 cm(-1).