Infrared multiple photon dissociation action spectroscopy of protonated unsymmetrical dimethylhydrazine and proton-bound dimers of hydrazine and unsymmetrical dimethylhydrazine
Infrared multiple photon dissociation action spectroscopy of protonated unsymmetrical dimethylhydrazine and proton-bound dimers of hydrazine and unsymmetrical dimethylhydrazine
复制标题
质子化不对称二甲肼以及肼和不对称二甲肼质子结合二聚体的红外多光子解离作用光谱
DOI：
10.1039/d1cp03781a
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发表时间：
2021
影响因子：
3.3
通讯作者：
Armentrout, P. B.
中科院分区：
文献类型：
--
作者：
McNary, Christopher P.;Demireva, Maria;Martens, Jonathan;Berden, Giel;Oomens, Jos;Hamlow, L. A.;Rodgers, M. T.;Armentrout, P. B.
利用自由电子激光器和光学参量振荡器激光系统产生的光，用红外多光子解离（IRMPD）作用光谱研究了质子化偏二甲肼（UDMH）以及质子束缚的UDMH和肼的二聚体的气相结构.为了鉴定实验研究中存在的结构，将测量的IRMPD光谱与在B3 LYP-GD 3BJ/6-311+G（d，p）理论水平下计算的光谱进行比较。这些比较表明，质子化的UDMH在甲基化的氮原子（α）上结合质子，可能存在两个低位α构象。对于（UDMH）2 H+，质子在甲基化的氮原子之间共享，可能存在几个低位α构象。根据IRPMD光谱，不能排除（UDMH）2 H+的高位构象，其中质子在α和β（未甲基化）氮原子之间共享。对于（N2 H4）2 H+，有四个低位构象，所有再现IRMPD光谱相当不错。由于联氨和偏二甲肼被用作火箭发动机的燃料，这种光谱作为远程监测火箭发射的一种手段可能是有用的，特别是在需要评估环境危害的发射失败的情况下。
The gas-phase structures of protonated unsymmetrical 1,1-dimethylhydrazine (UDMH) and the proton-bound dimers of UDMH and hydrazine are examined by infrared multiple photon dissociation (IRMPD) action spectroscopy utilizing light generated by a free electron laser and an optical parametric oscillator laser system. To identify the structures present in the experimental studies, the measured IRMPD spectra are compared to spectra calculated at the B3LYP-GD3BJ/6-311+G(d,p) level of theory. These comparisons show that protonated UDMH binds the proton at the methylated nitrogen atom (α) with two low-lying α conformers probably being populated. For (UDMH)2H+, the proton is shared between the methylated nitrogen atoms with several low-lying α conformers likely to be populated. Higher-lying conformers of (UDMH)2H+ in which the proton is shared between α and β (unmethylated) nitrogen atoms cannot be ruled out on the basis of the IRPMD spectrum. For (N2H4)2H+, there are four low-lying conformers that all reproduce the IRMPD spectrum reasonably well. As hydrazine and UDMH see usage as fuels for rocket engines, such spectra are potentially useful as a means of remotely monitoring rocket launches, especially in cases of unsuccessful launches where environmental hazards need to be assessed.