Abstract About 15,000 published transitions for methyl amine with J ≤ 40 have been refit using a hybrid program in which the NH2 wagging motion is treated by a tunneling formalism, while the CH3 internal-rotation motion is treated by the usual torsion-rotation Hamiltonian. Most of the fitted transitions are taken from published measurements. Compared to previous fits using the high barrier tunneling formalism for both motions, the present hybrid fit reduces the number of parameters in the Hamiltonian by about a factor of two, with essentially no increase in observed-minus-calculated residuals for the infrared transitions, and with an increase of about a factor of two for the microwave transitions. We showed that our approach can treat simultaneously for the first time the ground and first excited states of methylamine and can now be applied to (i) a much larger set of accurate vt = 1 microwave data, and (ii) infrared data on the vt = 2 ← 1 and 3 ← 2 torsional hot bands.

中文翻译：

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使用混合“隧道和非隧道”哈密顿形式主义同时拟合 CH3NH2 的 v = 0 和 1 扭转-摆动-旋转水平

摘要 大约 15,000 个已发表的 J ≤ 40 的甲胺跃迁已经使用混合程序进行了改装，其中 NH2 摆动运动由隧道形式主义处理，而 CH3 内部旋转运动由通常的扭转 - 旋转哈密顿量处理。大多数拟合过渡取自已发布的测量值。与之前对两种运动都使用高势垒隧道形式的拟合相比，本混合拟合将哈密顿量中的参数数量减少了大约两倍，而红外跃迁的观测减去计算残差基本上没有增加，并且微波跃迁增加了大约两倍。