中红外光学频率梳傅里叶变换光谱研究碘甲烷的$_4$带谱线位置和强度
Line Positions and Intensities of the ν$_4$ Band of Methyl Iodide Using Mid-Infrared Optical Frequency Comb Fourier Transform Spectroscopy
摘要：
我们使用光学频率梳傅里叶变换光谱测量碘甲烷，CH $_3$ I在C-H伸缩区域从2800到3160 cm $^{-1}$的高分辨率光谱。具有自动平衡检测的快速扫描傅里叶变换光谱仪基于重复率f $_{rep}$为125 MHz的差频发生梳。在不同的f $_{rep}$设置下测量具有等于f $_{rep}$的采样点间隔的一系列频谱，并将其交织以产生11 MHz的采样点间隔。利用室温下碘甲烷的蒸气压，将其引入76米长的多程吸收池中。测量的光谱包含三个主要的振转特征：以2850 cm $^{-1}$为中心的平行振动泛音和组合带，以2971 cm $^{-1}$为中心的对称拉伸$ν_1$带，以及以3060 cm $^{-1}$为中心的不对称拉伸$ν_4$带。用PGOPHER模拟了$ν_4$带和附近的$ν_3$ + $ν_4$ - $ν_3$热带的光谱，并对这些带进行了新的归属。解析的振转结构与微波数据一起用于最小二乘拟合，以提供上态参数。我们将2603个跃迁分配给$ν_4$带，标准差（观察-计算）为0.00034 cm $^{-1}$，将831个跃迁分配给$ν_3$ + $ν_4$ - $ν_3$热带，标准差为0.00084 cm $^{-1}$。在J $\leq$ 2 × K跃迁中观察到了由${^{127}}$ I核四极矩引起的超精细分裂。最后，首次报道了$ν_4$谱带中157个孤立跃迁的强度，并用Voigt线型作为多光谱拟合的模型。
英文摘要：
We use optical frequency comb Fourier transform spectroscopy to measure high-resolution spectra of iodomethane, CH$_3$I in the C-H stretch region from 2800 to 3160 cm$^{-1}$. The fast-scanning Fourier transform spectrometer with auto-balanced detection is based on a difference frequency generation comb with repetition rate, f$_{rep}$, of 125 MHz. A series of spectra with sample point spacing equal to f$_{rep}$ are measured at different f$_{rep}$ settings and interleaved to yield sampling point spacing of 11 MHz. Iodomethane is introduced into a 76 m long multipass absorption cell by its vapor pressure at room temperature. The measured spectrum contains three main ro-vibrational features: the parallel vibrational overtone and combination bands centered around 2850 cm$^{-1}$, the symmetric stretch $ν_1$ band centered at 2971 cm$^{-1}$, and the asymmetric stretch $ν_4$ band centered at 3060 cm$^{-1}$. The spectra of the $ν_4$ band and the nearby $ν_3$+$ν_4$-$ν_3$ hot band are simulated using PGOPHER and a new assignment of these bands is presented. The resolved ro-vibrational structures are used in a least square fit together with the microwave data to provide the upper state parameters. We assign 2603 transitions to the $ν_4$ band with standard deviation (observed - calculated) of 0.00034 cm$^{-1}$, and 831 transitions to the $ν_3$+$ν_4$-$ν_3$ hot band with standard deviation of 0.00084 cm$^{-1}$. The hyperfine splittings due to the ${^{127}}$I nuclear quadrupole moment are observed for transitions with J$\leq$2xK. Finally, intensities of 157 isolated transitions in the $ν_4$ band are reported for the first time using the Voigt line shape as a model in multispectral fitting.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
