The spectra of N-ethyl methyl amine, CH₃(NH)CH₂CH₃, were measured using a molecular jet Fourier transform microwave spectrometer in the frequency range of 2 GHz–26.5 GHz. Splittings due to proton inversion tunneling, Coriolis coupling, ¹⁴N quadrupole coupling, and methyl internal rotation were fully resolved. The experimentally deduced rotational constants are A = 25 934.717(21) MHz, B = 3919.8212(23) MHz, and C = 3669.530(21) MHz. The proton tunneling causes (+) ↔ (−) splittings of about 1980.9 MHz for all c-type transitions between the lowest symmetric and the higher anti-symmetric energy levels. The splittings of the (+) ← (+) and (−) ← (−) levels, mainly influenced by Coriolis coupling, were also observed and assigned for b-type transitions, yielding the coupling constants F_bc = 0.3409(71) MHz and F_ac = 163.9(14) MHz. The ¹⁴N quadrupole coupling constants were determined to be χ_aa = 2.788 65(55) MHz and χ_bb − χ_cc = 4.630 45(91) MHz. Fine splittings arising from two inequivalent methyl rotors are in the order of 150 kHz, and the torsional barriers are determined to be 1084.62(41) cm⁻¹ for the CH₃NH methyl group and 1163.43(80) cm⁻¹ for the CH₂CH₃ methyl group. The experimental results are in good agreement with those of quantum chemical calculations.

中文翻译：

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乙基甲基胺的微波光谱中质子隧穿，14N四极偶合和甲基内旋的影响

的光谱ñ -乙基甲胺，CH ₃（NH）CH ₂ CH ₃，使用分子射流2 GHz的-26.5GHz的频率范围内傅立叶变换光谱仪的微波测定。完全解决了由于质子倒置隧穿，科里奥利耦合，¹⁴ N四极耦合和甲基内旋引起的分裂。实验得出的旋转常数为A = 25 934.717（21）MHz，B = 3919.8212（23）MHz和C = 3669.530（21）MHz。质子隧穿导致所有c的（+）↔（-）分裂约为1980.9 MHz最低对称能级和较高反对称能级之间的α型跃迁。还观察到主要受科里奥利耦合影响的（+）←（+）和（-）←（-）能级的分裂并将其分配给b型跃迁，从而产生耦合常数F _bc = 0.3409（71）MHz和˚F _AC = 163.9（14）兆赫。在^14个Ñ四极耦合常数被确定为χ _AA = 2.788 65（55）MHz和χ _BB - χ _CC = 4.630 45（91）兆赫。两个不等价的甲基转子产生的细裂约为150 kHz，扭转壁垒确定为1084.62（41）cm^-1用于CH ₃ NH甲基和1163.43（80）厘米^-1为CH ₂ CH ₃甲基。实验结果与量子化学计算结果吻合良好。