First real-time measurement of the evolving 2H/1H ratio during water evaporation from plant leaves

We have studied the temporal behaviour of the deuterium isotope ratio of water vapour emerging from a freshly cut plant leaf placed in a dry nitrogen atmosphere. The leaf material was placed directly inside the sample gas cell of the stable isotope ratio infrared spectrometer. At the reduced pressure (～40 mbar) inside the cell, the appearance of water evaporating from the leaf is easily probed by the spectrometer, as well as the evolving isotope ratios, with a precision of about 1 ‰. The demonstration experiment we describe measures the ²H/¹H isotope ratio only, but the experiment can be easily extended to include the ¹⁸O/¹⁶O and ¹⁷O/¹⁶O isotope ratios. Plant leaf water isotope ratios provide important information towards quantification of the different components in the ecosystem water and carbon dioxide exchange.     

基于可见近红外光谱的糖类别快速鉴别研究

提出了一种用近红外光谱技术快速鉴别糖类别的新方法.采用近红外光谱获取白砂糖、木糖醇、双歧糖和葡萄糖等四种糖类别的光谱反射特征曲线,采用偏最小二乘法进行模式特征分析,经过交互验证法判别,确定最佳主成分数为11.完成特征提取后,将11种主成分作为神经网络的输入变量,建立了3层BP神经网络.四个类别的糖样本数均为40,共计160个样本,将其分成训练集样本120个和预测集样本40个,对40个未知样本进行预测,准确率为100%.说明所提出的方法对于糖类别具有很好的分类和鉴别能力.     

Vibrational properties and Raman spectra of different edge graphene nanoribbons,studied by first-principles calculations

The vibrational properties and Raman spectra of graphene nanoribbons with six different edges have been studied by using the first-principles calculations. It is found that edge reconstruction leads to the emergence of localized vibrational modes and new topological defect modes, making the different edges identified by polarized Raman spectra. The radial breathing-like modes are found to be independent of the edge structures, while the G-band-related modes are affected by different edge structures. Our results suggest that the polarized Raman spectrum could be a powerful experimental tool for distinguishing the GNRs with different edge structures due to their different vibrational properties.     

Laser Ionization Spectroscopy of Octafluorocyclooctatetraene

Two- and three-photon resonant ionization spectroscopy is used to explore the high-lying electronic states of octafluorocyclooctatetraene (OFCOT). CNDO/S calculations are reported as an aid in the assignment of the observed valence transitions. The spectra agree quite well with the predictions of the semi-empirical method, which has not been previously tested at such high energies. The ionization potential for this molecule is estimated and the effects of “through-space” and “through-bond” coupling on the energy levels are discussed. Comparison is made to the already reported spectroscopy of the hydrocarbon analog.     

近红外光谱法同时测定葵花粕中油,蛋白质,水分和粗纤维

本文介绍了应用６２５０型近红外光谱仪和ＮＳＡＳ－ＰＣ软件测定葵花粕中油，蛋白质，水分和粗纤维的方法，首先应用回归分析建立起样品的近红外光谱与各成分含量之间的多元线性关系－即定标，然后对定标进行验证，结果表明近红外光谱分析法与可以取代标准化学进行葵花粕中成分含量的测定，并且具有快速，简便，无试剂污染的优点。     

抚顺地区大气总悬浮微粒元素浓度季节变化的研究

本文采用X射线荧光法对抚顺地区大气总悬浮微粒（TSP）中S等20种元素的浓度水平进行分析，并通过无素的富集因子分析探讨TSP元素富集特征和污染来源，结果表明：采用暖期TSP浓度水平明显超过国家三级标准，其中富集程度较高的S，As,Zn等主要来源于煤炭燃烧。     

基于光谱技术和连续投影算法的润滑油品牌快速鉴别研究

为了实现润滑油品牌的快速无损检测,提出了一种基于可见/近红外光谱透射技术与连续投影算法相结合的润滑油品牌快速鉴别新方法。采用连续投影算法对6种润滑油的可见/近红外光谱数据进行波长变量的筛选,再结合偏最小二乘法建立润滑油品牌的鉴别模型。结果表明,鉴别模型的相关系数r为0.9721,预测均方根误差RMSEP为0.4055,鉴别正确率为91.7%。说明提出的连续投影算法结合偏最小二乘算法具有很好的预测效果。     

γ-丁内酯溶剂效应的红外光谱

在19种不同有机溶剂中测定γ-丁内酯的红外光谱,研究溶质-溶剂间相互作用,并进行了溶质的羰基伸缩振动频率位移与溶剂参数相关性分析。结果表明,在所考察的溶剂(除正己烷和环己烷外)中,γ-丁内酯与溶剂间形成非键缔合物。缔合物的羰基伸缩振动频率(带)和游离γ-丁内酯的羰基伸缩振动频率(带)位移与溶剂参数AN、S值、ET(30)值、G值、Swain参数Aj和Bj以及LSER间具有较好的线性相关性。溶剂与γ-丁内酯相互作用中,溶剂的接受电子对的能力和极性起着重要作用。这意味着溶剂与γ-丁内酯形成非键缔合物时的主要作用力是氢键作用和偶极-偶极作用。     

Rotational spectrum of the v11 = 1 and v14 = 1 vibrational states of CH3CCCCH

The pure rotational spectra of the v₁₁ = 1 and v₁₄ = 1 vibrational states of the main isotopic species of methyldiacetylene have been recorded and assigned in the 80-400 GHz frequency range, spanning the quantum numbers 19 ? J ? 95 and 0 ? K ? 15. The present study allows us to provide accurate rotational, centrifugal distortion and vibration-rotation interaction constants. The experimental investigation has been strongly supported by quantum-chemical computations at the second-order Møller-Plesset theory (MP2) in conjunction with a triple-zeta quality basis set.     

Experimental deduction of In/Si(1 1 1) 2D phase diagram and ab initio DFT modeling of 2√3 phase

We have carried out adsorption and residual thermal desorption experiments of Indium on Si (1 1 1) 7 × 7 reconstructed surface, in the submonolayer regime, in Ultra High Vacuum (UHV) using in situ probes such as Auger Electron Spectroscopy (AES) and Low Energy Electron Diffraction (LEED). The coverage information from AES and the surface symmetry from LEED is used to draw a 2D phase diagram which characterizes each observed superstructural phases. The different superstructural phases observed are Si(1 1 1)7 × 7-In, Si(1 1 1)√3 × √3R30°-In, Si(1 1 1)4 × 1-In, Si(1 1 1)2√3 × 2√3R30°-In and Si(1 1 1)√7 × √3-In in characteristic temperature and coverage regime. In addition to the 1/3 ML, √3 × √3-In phase, we observe two additional √3 × √3-In phases at around 0.6 and 1 ML. Our careful residual thermal desorption studies yields the Si(1 1 1)2√3 × 2√3R30°-In phase which has infrequently appeared in the literature. We probe theoretically the structure of this phase according to the LEED structure and coverage measured by AES, assuming that the model for Si(1 1 1)2√3 × 2√3R30°-In is very proximal to the well established Si(1 1 1)2√3 × 2√3R30°-Sn phase, using ab initio calculation based on pseudopotentials and Density Functional Theory (DFT) to simulate an STM image of the system. Calculations show the differences in the atomic position and charge distribution in the Si(1 1 1)2√3 × 2√3R30°-In case.