The first excited torsional state of the chiral molecule propylene oxide, ${\mathrm{CH}}_3{\mathrm{C}}_2{\mathrm{H}}_3\mathrm{O}$, is investigated from millimeter up to sub-millimeter wavelengths (75–950 GHz). The first excited vibrational mode of propylene oxide, ${\upsilon }_{24}$, is analysed using the programs ERHAM and XIAM. Rotational constants and tunneling parameters are provided, and a description of the A-E splittings due to internal rotation is given. Furthermore, the potential barrier height to internal rotation, $V_3$, is determined to be $V_3=898.6611\left(894\right){\mathrm{cm}}^{-1}$. Our results are compared with quantum chemical calculations and literature values. We present a line list of the dense spectrum of the first excited torsional state of propylene oxide in the (sub-) millimeter range. Our results will be useful for further studies of chiral molecules in vibrationally excited states and will enable astronomers to search for rotational transitions originating from ${\upsilon }_{24}$ of propylene oxide in interstellar space.

手性分子环氧丙烷的第一个激发扭转态 ${\mathrm{CH}}_3{\mathrm{C}}_{\mathrm{2个}}{\mathrm{H}}_3\mathrm{Ø}$从毫米到亚毫米波长（75–950 GHz）进行了研究。环氧丙烷的第一个激发振动模式${\upsilon }_{24}$使用程序ERHAM和XIAM进行分析。提供了旋转常数和隧穿参数，并给出了由于内部旋转而导致的AE分裂的描述。此外，内部旋转的势垒高度${\mathrm{伏特}}_3$，确定为 ${\mathrm{伏特}}_3=898.6611（894）{\mathrm{厘米}}^{--\mathrm{1个}}$。我们的结果与量子化学计算和文献值进行了比较。我们提出了（亚）毫米范围内的环氧丙烷的第一激发扭转态的致密光谱的线列表。我们的结果将有助于进一步研究处于振动激发态的手性分子，并使天文学家能够搜索源自于手性分子的旋转跃迁${\upsilon }_{24}$ 星际空间中的环氧丙烷。