Pulsed-beam Fourier transform microwave spectroscopy was used to observe and assign the rotational spectra of the argon-ketene van der Waals complex. Tunneling of the hydrogen or deuterium atoms splits the a- and b-type rotational transitions of H(2)CCO-Ar, H(2)(13)CCO-Ar, H(2)C(13)CO-Ar, and D(2)CCO-Ar into two states. This internal motion appears to be quenched for HDCCO-Ar where only one state is observed. The spectra of all isotopomers were satisfactorily fit to a Watson asymmetric top Hamiltonian which gave A=10 447.9248(10) MHz, B=1918.0138(16) MHz, C=1606.7642(15) MHz, Delta(J)=16.0856(70) kHz, Delta(JK)=274.779(64) kHz, Delta(K)=-152.24(23) kHz, delta(J)=2.5313(18) kHz, delta(K)=209.85(82) kHz, and h(K)=1.562(64) kHz for the A(1) state of H(2)CCO-Ar. Electric dipole moment measurements determined &mgr;(a)=0.417(10)x10(-30) C m [0.125(3) D] and &mgr;(b)=4.566(7)x10(-30) C m [1.369(2) D] along the a and b principal axes of the A(1) state of the normal isotopomer. A least squares fit of principal moments of inertia, I(a) and I(c), of H(2)CCO-Ar, H(2)(13)CCO-Ar, and H(2)C(13)CO-Ar for the A(1) states give the argon-ketene center of mass separation, R(cm)=3.5868(3) Å, and the angle between the line connecting argon with the center of mass of ketene and the C=C=O axis, θ(cm)=96.4 degrees (2). The spectral data are consistent with a planar geometry with the argon atom tilted toward the carbonyl carbon of ketene by 6.4 degrees from a T-shaped configuration. Copyright 2001 Academic Press.

中文翻译：

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Argon-Ketene van der Waals 络合物的旋转光谱、结构、内部动力学和电偶极矩

脉冲束傅里叶变换微波光谱用于观察和分配氩-乙烯酮范德华配合物的旋转光谱。氢或氘原子的隧穿分裂了 H(2)CCO-Ar、H(2)(13)CCO-Ar、H(2)C(13)CO-Ar 和 b 型旋转跃迁D(2)CCO-Ar 进入两种状态。对于只观察到一种状态的 HDCCO-Ar，这种内部运动似乎被淬灭。所有同位素异构体的光谱都与 Watson 不对称顶哈密顿量吻合，得出 A=10 447.9248(10) MHz，B=1918.0138(16) MHz，C=1606.7642(15) MHz，Delta(J)=16.0856(70) kHz, Delta(JK)=274.779(64) kHz, Delta(K)=-152.24(23) kHz, delta(J)=2.5313(18) kHz, delta(K)=209.85(82) kHz, h(对于 H(2)CCO-Ar 的 A(1) 状态，K)=1.562(64) kHz。确定的电偶极矩测量值 &mgr;(a)=0.417(10)x10(-30) C m [0. 125(3) D] 和 &mgr;(b)=4.566(7)x10(-30) C m [1.369(2) D] 沿正常同位素异构体 A(1) 状态的 a 和 b 主轴。H(2)CCO-Ar、H(2)(13)CCO-Ar 和 H(2)C(13)CO 的主惯性矩 I(a) 和 I(c) 的最小二乘拟合A(1) 状态的 -Ar 给出氩-乙烯酮质心分离，R(cm)=3.5868(3) Å，以及连接氩与乙烯酮质心的线与 C=C 之间的夹角=O 轴，θ(cm)=96.4 度 (2)。光谱数据与平面几何形状一致，其中氩原子从 T 形构型向乙烯酮的羰基碳倾斜 6.4 度。版权所有 2001 学术出版社。对于 A(1) 状态，H(2)CCO-Ar、H(2)(13)CCO-Ar 和 H(2)C(13)CO-Ar 的 I(a) 和 I(c) 给出氩-乙烯酮质心分离，R(cm)=3.5868(3) Å，氩与乙烯酮质心连线与C=C=O轴的夹角θ(cm)=96.4度 (2)。光谱数据与平面几何形状一致，其中氩原子从 T 形构型向乙烯酮的羰基碳倾斜 6.4 度。版权所有 2001 学术出版社。对于 A(1) 状态，H(2)CCO-Ar、H(2)(13)CCO-Ar 和 H(2)C(13)CO-Ar 的 I(a) 和 I(c) 给出氩-乙烯酮质心分离，R(cm)=3.5868(3) Å，氩与乙烯酮质心连线与C=C=O轴的夹角θ(cm)=96.4度 (2)。光谱数据与平面几何形状一致，其中氩原子从 T 形构型向乙烯酮的羰基碳倾斜 6.4 度。版权所有 2001 学术出版社。光谱数据与平面几何形状一致，其中氩原子从 T 形构型向乙烯酮的羰基碳倾斜 6.4 度。版权所有 2001 学术出版社。光谱数据与平面几何形状一致，其中氩原子从 T 形构型向乙烯酮的羰基碳倾斜 6.4 度。版权所有 2001 学术出版社。