光泵甲胺分子太赫兹激光谱线的新标识

New Assignments of the Optically Pumped Terahertz Laser Lines of Methylamine

研发光泵分子太赫兹激光器是填补"THz gap"的最有效手段之一。甲胺分子(CH3NH2)是这种太赫兹激光器的良好媒质之一,因为它的C—N伸缩振动带的中心频率(约1 044cm-1)与CO2气体激光器的辐射带很接近。我们精密地观测记录了甲胺分子C—N伸缩带的高分辨率傅里叶变换红外光谱及其兰姆凹陷饱和吸收光谱,清晰地标识了大量的红外跃迁谱线。以此及前期工作为基础,我们对由CO2激光泵浦的甲胺分子太赫兹激光谱线进行了标识,并根据里兹组合原理对其进行了确认,发现频率闭环残差与实验测量误差符合得很好,从而证实了新标识的太赫兹激光谱线的正确性。

The development of optically pumped terahertz(THz)laser of molecules is one of the most effective tools to fill the 'THz gap'.Methylamine(CH3NH2)has been an important member of the class of laser media used to generate THz laser lines by optically pumping with CO2 laser lines,because the C—N stretching band of CH3NH2 displays strong characteristic absorptions in the infrared region around 1 044cm-1,which overlaps well with the CO2 laser bands.For this C—N stretching band of CH3NH2,we precisely observed the high-resolution Fourier transform infrared spectrum and the Lamb-dip saturated absorption spectrum,and assigned many infrared transitions,which benefited us to newly assign a few more THz laser lines pumped by the9P(24)CO2laser lines.According to the Ritz's combination principle,the confirmations to these assignments were carried out by forming the closed loops which contained infrared and THz transitions and by calculating the loop defects.The fact that these loop defects consistedwith the experimental uncertainty confirmed both of the infrared and THz transition assignments in each of the loops.