We present a combined experimental and ab initio study on the jet-cooled high-resolution infrared spectra of the ν₁ (acetylenic stretch) fundamental band for three isotopologues of propyne: ¹³CH₃¹²C≡¹²CH, ¹²CH₃¹³C≡¹²CH, and ¹²CH₃¹²C≡¹³CH. The experimental spectra are recorded in natural abundance using a continuous supersonic expansion of regular propyne diluted in argon and helium, in combination with continuous wave cavity ring-down spectroscopy (cw-CRDS). The fully rotationally resolved K’ = 0 and 1 subbands of all three monosubstituted ¹³C isotopologues have been measured near 3330 cm^–1, and their spectroscopic analysis is presented here for the first time. The assignment of the bands and perturbation analysis are assisted by high level ab initio calculations at the CCSD(T) level of theory, from which vibrational frequencies, rotational constants, and Fermi resonances are predicted for each isotopologue.

中文翻译：

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在ν的高分辨率红外光谱₁单取代的基本带¹³ Ç丙炔同位素异

我们提出了一个组合的实验和从头在ν的射流冷却高分辨率红外光谱研究₁（炔拉伸）基本频带丙炔三种同位素：¹³ CH ₃ ¹² C≡ ¹² CH，¹² CH ₃ ¹³ C≡ ¹² CH，和¹² CH ₃ ¹² C≡ ¹³ CH。使用连续的超声稀释在氩气和氦气中稀释的常规丙炔进行超声扩展，结合连续波腔衰荡光谱法（cw-CRDS），以自然丰度记录实验光谱。完全旋转分解的K'在3330 cm ^–1附近测量了所有三个单取代¹³ C同位素的0和1个子带，此处首次进行了光谱分析。在理论上的CCSD（T）水平上，通过高水平的从头算起，可以帮助分配能带和进行扰动分析，由此可以预测每个同位素分子的振动频率，旋转常数和费米共振。