NO_2的自增宽及N_2O_4和CO_2外加气体压致增宽系数的激光磁共振方法测量

激光磁共振光谱方法被用来研究NO_2的v_3振转带谱线的线宽及压致增宽。通过实验测量及数据分析得到了NO_2的自增宽系数及外来气体N_2O_4和CO_2对它的压致增宽系数,γ_(NO_2-NO_2N_2O_4CO_2)=0.043±0.005,0.014±0.003,0.013±0.003MHz/Pa(HWHM),并由此得到了相应的碰撞截面。这些参数的获得对大气污染监测具有十分重要的意义。     

NO,NO_2超精细LMR谱的观测

采用内腔CO激光磁共振光谱方法和微机数据采样系统,观测到了NO,NO_2分子的超精细激光磁共振(LMR)谱,简述了测量原理,给出了实验结果。     

激光磁共振光谱方法的进展

本文介绍了激光滋共振光谱方法近几年来的新发展，其中包括实验系统的改进，以及采用磁旋转方法、双调制方法、双共振方法和时间分辨方法的激光磁共振新技术．用这些方法对许多自由基分子、离子分子和激发态分子作了测量，同时也介绍了它们的一些应用．     

自由基分子NH2ν2带CO激光磁共振π谱的观测

采用高灵敏度、高分辨率激光磁共振光谱(LMR)方法在6μm谱段测量了自由基分子NH₂ν₂带的π谱(ΔM_J=0).测量了前人已测过的谱,结果与之较好符合.并观测到了前人没有观测过的新谱,在3支激光谱线下共获得约13支塞曼(Zeeman)跃迁谱线,其中在2支激光谱线下新测得的谱线10支.利用我们已经测得的^[8]σ谱的新的共振谱线的数值和已取得的激光磁共振谱线的标识方法,可预期得到NH₂的一些新的分子参数.     

自由基分子NH2υ2带CO激光磁共振σ谱的观测

采用高灵敏度,高分辨率激光磁共振光谱(LMR)方法在6μm谱段测量了自由基分子NH₂υ₂带的σ谱(△M_J=±1)。重复了前人已测过的谱,结果与之较好符合。并观测到了新谱,在14支激光谱线下共获得约115支塞曼(Zeeman)跃迁谱线,其中在6支激光谱线下新测得的谱线91支。     

远红外激光磁共振光谱技术及对含碳自由基分子的观测

本文报道国内建成的远红外激光磁共振 (FIRLMR)光谱仪的技术特点和工作原理。该谱仪采用CO2 激光横向泵浦远红外激光 ,样品吸收池置于远红外激光谐振腔内 ,由聚丙烯薄膜与远红外激光增益池隔开以获得很高的灵敏度 ,从而对寿命很短的自由基分子进行研究。利用该光谱仪在远红外波段测量得到了多个瞬态自由基分子CCH ,CF和CH2 的光谱 ,这些自由基分子由微波放电产生的氟原子与甲烷CH4 反应生成。     

自由基分子NH_2υ_2带C0激光磁共振σ谱的观测

采用高灵敏度,高分辨率激光磁共振光谱(LMR)方法在6μm谱段测量了自由基分子NH_2v_2带的σ谱(△M_1=±1)。重复了前人已测过的谱,结果与之较好符合。并观测到了新谱,在14支激光谱线下共获得约115支塞曼(Zeeman)跃迁谱线,其中在6支激光谱线下新测得的谱线91支。     

NO2ν2振动带的CO2激光磁共振垂直谱的观测

采用高灵敏度、高分辨率激光磁共振光谱(LMR)方法,使用CO₂激光器测量了分子NO₂v₂振动带的垂直谱(△M_J=±1).观测到了前人没有测过的新谱,在22支激光谱线下新获得100支塞曼(Zeeman)跃迁谱线。     

NO2的自增宽及N2O4和CO2外加气体压致增宽系数的激光磁共振方法测量

激光磁共振光谱方法被用来研究NO₂的v₃振转带谱线的线宽及压致增宽。通过实验测量及数据分析得到了NO₂的自增宽系数及外来气体N₂O₄和CO₂对它的压致增宽系数,γ_{NO2-NO2N2O4CO2}⁰=0.043±0.005,0.014±0.003,0.013±0.003MHz/Pa(HWHM),并由此得到了相应的碰撞截面。这些参数的获得对大气污染监测具有十分重要的意义。     

The infrared spectrum of the AsD radical in its XΣ state, recorded by laser magnetic resonance

The infrared spectrum of the AsD radical in the X³Σ⁻ ground state has been recorded using CO laser magnetic resonance. The radical was formed by the reaction between D atoms and arsenic powder. Low-N transitions in the fundamental band and in the (2-1) and (3-2) hot bands have been detected. Hyperfine structure from the ⁷⁵As nucleus (I = 3/2) is seen on many of the resonances. These measurements have been combined with information from previous measurements of rotational transitions at sub-millimeter wavelengths [H. Fujiwara, K. Kobayashi, H. Ozeki, S. Saito, A.I. Jaman, J. Chem. Soc. Faraday Trans. 93 (1997) 1045-1051] to determine an extended and improved set of molecular parameters for ⁷⁵AsD. Comparison is made with corresponding parameter values for AsH.     

Weighted iterative inversion method for T2 spectrum in nuclear magnetic resonance

Abstract

In traditional nuclear magnetic resonance T₂ inversion methods, the components with long T₂ absorb the components with short T₂, especially for low magnetic field intensity. As a result, the true distribution of all components often cannot be reflected by their solutions, and thus obtaining short T₂ components is an important T₂ inversion problem. Herein, a weighted iterative inversion method for T₂ spectrum in nuclear magnetic resonance is proposed to solve this problem. The weight-based method is applied to ensure that the short T₂ components are not eliminated. The weight scheme is determined by two parameters: the number of weights and maximum weight. The number of weights is determined by the rate of decay, and the maximum weight is mainly determined by three parameters: signal-noise ratio, curvature, and slope of collected signal. To avoid the mutations of results caused by weights, the iteration process was adopted to obtain the optimal solution. The proposed method provides good results, and it was verified to be robust and accurate though simulations and experiments.     

Dynamic H nuclear magnetic resonance of rotating solids

The sensitivity of one-dimensional dynamic magic-angle spinning (MAS) and off-MAS ²H nuclear magnetic resonance spectra to changes in the parameters of jump-type molecular motions is studied. The Floquet theory approach is used to simulate spectra of spins with I = 1, which are involved in exchange processes in rotating solids. The solution of the Bloch-McConnell equations for rotating samples are derived and some simulated frequency spectra are shown. The dependence of the lineshapes of the center and sidebands of the MAS and off-MAS spectra on the exchange parameters are discussed. Experimental results of ²H spectra of perdeuterated dimethyl sulfone, obtained in the temperature range 20–55 °C, are demonstrated. The methyl groups in this molecule undergo π flips at rates that can be detected by MAS and off-MAS NMR. The shapes of the experimental sidebands are compared with simulated results.     

Analysis of far-infrared laser magnetic resonance spectra of CH2Br at 447.3 and 671.1μm

A simple model has been developed to describe the Zeeman patterns of far-infrared laser magnetic resonance spectra of the monobromomethyl radical CH₂Br observed at 447.3 and 671.1μm. A satisfactory agreement between the experimental spectra of the radical and their simulation with this simple model has been achieved. This approach can be used to gain further information about the structure and the spectrum of this interesting radical.