High-resolution microwave spectrum of the weakly bound helium-pyridine complex.
High-resolution microwave spectrum of the weakly bound helium-pyridine complex.
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DOI：
10.1063/1.2751186
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发表时间：
2007-07
期刊：
影响因子：
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通讯作者：
C. Tanjaroon;W. Jäger
中科院分区：
文献类型：
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作者：
C. Tanjaroon;W. Jäger
用脉冲分子束傅里叶变换微波光谱仪获得了氦-吡啶二聚体的高分辨转动光谱。观测并归属了a型和c型偶极跃迁的39个R分支(14)N核四极超精细成分。得到的光谱参数为：转动常数A=3875.2093(48)MHz，B=3753.2514(45)MHz，C=2978.4366(81)MHz，四次离心变形常数D(J)=0.124 08(55)MHz，D(JK)=0.1200(43)MHz，D(K)=-0.2451(25)MHz，d(1)=0.004 27(27)MHz，d(2)=0.000 16(10)MHz；六次离心扭曲常数H(J)=0.003 053(35)MHz，H(JK)=-0.006 598(47)MHz，H(K)=0.004 11(59)MHz；(14)N核四极耦合常数chi(AA)(14)N=-4.7886(76)MHz，chi(BB)(14)N)=1.4471(76)MHz，chi(Cc)(14)N)=3.3415(43)MHz。我们对旋转和(14)N四极耦合常数的分析表明，He原子垂直于C(5)H(5)N的芳香族平面，与吡啶单体的c轴成大约7.0度的位移角，朝向氮原子。在二阶Moller-Plesset水平上进行从头算结构优化的结果与该几何结构一致，给出了86.7 cm(-1)的平衡势垒深度。
High-resolution rotational spectra of the helium-pyridine dimer were obtained using a pulsed molecular beam Fourier transform microwave spectrometer. Thirty-nine R-branch (14)N nuclear quadrupole hyperfine components of a- and c-type dipole transitions were observed and assigned. The following spectroscopic parameters were obtained: rotational constants A=3875.2093(48) MHz, B=3753.2514(45) MHz, and C=2978.4366(81) MHz; quartic centrifugal distortion constants D(J)=0.124 08(55) MHz, D(JK)=0.1200(43) MHz, D(K)=-0.2451(25) MHz, d(1)=0.004 27(27) MHz, and d(2)=0.000 16(10) MHz; sextic centrifugal distortion constants H(J)=0.003 053(35) MHz, H(JK)=-0.006 598(47) MHz, and H(K)=0.004 11(59) MHz; (14)N nuclear quadrupole coupling constants chi(aa)((14)N)=-4.7886(76) MHz, chi(bb)((14)N)=1.4471(76) MHz, and chi(cc)((14)N)=3.3415(43) MHz. Our analyses of the rotational and (14)N quadrupole coupling constants show that the He atom binds perpendicularly to the aromatic plane of C(5)H(5)N with a displacement angle of approximately 7.0 degrees away from the c axis of the pyridine monomer, toward the nitrogen atom. Results from an ab initio structure optimization on the second order Moller-Plesset level are consistent with this geometry and gave an equilibrium well depth of 86.7 cm(-1).