新型光声光谱法测定总无机碳酸盐含量

采用新型富氏变换红外光谱气体分析仪测定固体及水体样品中总无机碳酸盐含量,原理是CO₂对红外线的主动式光声吸收.反应器浸没在恒温水浴中,经氮气吹洗后,在连续搅动条件下,向样品中加入一定量高氯酸.酸解生成的CO₂对特定波段的红外吸收造成温度和压力的波动,从而产生频率取决于吸收波长的光声信号,再由微型麦克风加以记录.实验对固体和液体标准样品的线性检测范围分别为120 mg的CaCO₃和36.4 mmol/L的NaHCO₃,灵敏度分别为0.02 mg和3 mmol/L.因总无机碳酸盐的酸性缓冲容量对黏土矿物的表面酸碱性质影响显著,故选择不同来源天然伊利石作为模型样品进行测定,并探讨一些影响因素和改进方案.     

Diurnal variation of aethalometer correction factors and optical absorption assessment of nucleation events using multi-wavelength photoacoustic spectroscopy

A field measurement campaign was carried out during the late winter and early spring of2015 in Budapest, the capital of Hungary. The size distribution(SD) and optical absorption of carbonaceous particulate matter(CPM) was measured online using a Scanning Mobility Particle Sizer(SMPS), a 7λ-aethalometer and an inhouse developed 4λ-Photoacoustic Spectrometer. Based on the SD data, the measurement period could be classified into days with and without new particle formation events(normal days and nucleation days),although particular nucleation-like events were observed on normal days as well. Three characteristic size modes were observed with CMDs of circa 15, 25 and 110 nm that corresponded to the nucleation, traffic and heating modes. Based on the temporal behavior of these modes both types of days were divided into distinctive daily periods(heating hours,traffic hours and nucleation hours). The optical absorption spectra(OAC and AAE) also displayed the same part of day behavior to that of SD. That way this paper is among the first to assess the optical response of urban nucleation events. Due to the simultaneous measurement of OAC by the 7λ-aethalometer and a 4λ-Photoacoustic Spectrometer, OAC was measured overall at 11 wavelengths. That way aethalometer correction factors(f and C)were determined at all aethalometer wavelengths using in situ reference photoacoustic measurements. Correction factors were found to have both wavelength and time of the day variation. In the case of f, no clear trend could be observed, however, Cref values increased both as a function of wavelength.     

Real-time and in situ determination of ammonia concentrations in the atmosphere by means of intermodulated stark resonant CO2 laser photoacoustic spectroscopy

A concept of Intermodulated Photoacoustic Stark Spectroscopy (IMPASS) was used in an attempt to perform the interference-free field measurement of trace ammonia (3–40 ppbv) concentration levels in the air with a time resolution of 40 s.     

Intercomparison of photoacoustic and thermal-optical methods for the measurement of atmospheric elemental carbon

Two atmospheric elemental carbon measurement methods based on different analytical principles have been compared using data collected during the summer of 1987 at the Claremont, California site of the Southern California Air Quality Study (SCAQS). An optical absorption method, photoacoustic spectroscopy, measured the visible light absorption (γ = 514.5 nm) of atmospheric elemental carbon in its natural aerosol-state in real time. Elemental carbon concentrations were obtained by applying the appropriate value of the absorption cross-section for elemental carbon to the optical absorption data. The other method was a thermal-optical technique, which measures elemental and organic carbon concentrations on a filte--collected sample by combustion and corrects for the pyrolytic conversion of organic to elemental carbon by measuring the transmittance of laser light through the sample. Aerosol was collected on a filter mounted inside the carbon analyzer and analyzed in place. A 2-h collection and analysis cycle was used. The real-time photoacoustic data integrated over ∼100 min were compared with thermal-optical data. The two methods compare quite well. The linear least squares fit gave a correlation coefficient of R=0.905, and no significant difference was seen between the two data sets at the 95% confidence level.     

应用红外方法探讨耐镉菌株高积累Cd2+的机理

从安徽某冶炼厂污染土壤中分离出一株能耐高浓度镉的菌株(J5),经初步鉴定为假单胞菌属(Pseudomonas sp.).该菌株在液体培养基中耐受40 mmol·L-1 CdSO4,在固体培养基上耐受75mmol·L-1 CdSO4.培养基中Cd2+、Zn2+、Pb2+、Cu2+浓度分别为100 mg·L-1和Mn2+浓度为275mg·L-1时,菌株生长正常.在重金属Cu2+、Pb2+、Zn2+、Mn2+存在时,采用红外光谱与原子吸收光谱分析菌株对Cd2+的积累,结果表明,在低浓度Cd2+溶液中菌株细胞对Cd2+的积累,主要靠细胞壁上-NH2与Cd2+配位结合;在高浓度Cd2+溶液中,细胞壁上-NH2、-OH、-COOH、-PO43-、-M-O(O-M-O)基团吸附Cd2+的能力显著.Mn2+可以增加细胞壁上有效官能团活性,提高Cd2+积累率;但当有Zn2+、Pb2+、Cu2+重金属离子共存时,即使有Mn2+存在,菌体对Cd2+吸附积累能力未见提高.     

红外光谱技术应用的进展

对红外光谱(IR)分析技术的研究进展和应用现状进行综述,叙述了漫反射、衰减全反射、连用技术、傅立叶红外光谱仪的研制进展和红外光谱技术在医药、化工、环境等方面的应用.     

Infrared observations of H II regions

For many years emission nebulae like the Great Nebula in Orion were considered essentially as ionized hydrogen clouds (HII regions) to be understood with the methods of plasma physics. Infrared observations at wavelengths between 1 and 20 μm from the ground, and in the far infrared (20 μm-1 mm) from above the atmosphere, have shown these regions to be strong infrared emitters. This radiation is due to thermal emission of dust mixed with the gas and heated by hot young stars. HII regions indicate recent star formation, and close to these regions many other signposts of early stellar development can be studied in the infrared.     

Characterization of the fate of lipids in activated sludge

Experiments were carried out to characterize the transformation of lipids in activated sludge under aerobic conditions. Results showed that the overall lipid content in the effluent could not be reduced to values below 300 mg/L from an initial content of 2, 000 mg/L. However, the contents of individual fatty acids underwent drastic decreases and increases during all microbial growth phases. These changes in contents of individual fatty acids showed that fatty acids were used as substrates by microorganisms as well as released into the wastewater as by-products. We have therefore suggested a novel model of transformation of lipids in activated sludge, showing that utilization of microbial activity for complete removal of lipids from wastewater is limited.     

红外辐射大气透过率研究综述

随着红外技术的不断发展和在军事上的广泛运用,红外辐射在大气中的传输研究越来越受到关注.大气透过率是研究红外辐射传输的重要参数.基于红外辐射大气传输的基本理论结合近年来国内外的研究成果,从理论研究和软件平台2个方面对计算大气透过率的研究进展进行了综述,并探讨了复杂气象条件对大气透过率的影响,最后进行了总结和展望.     

量子点红外探测器的性能优化

量子点红外探测器是近年来出现的一种新型低维纳米结构探测器,因其优越的特性引起了人们的广泛关注。本文给出了一种估算量子点红外探测器光电流的方法,并以此为基础,进一步研究了探测器结构对光电流性能的影响。结果显示,当结构参数层内量子点密度和量子点横向尺寸的取值都比较小时,探测器能获得一个高的光电流。     

Optical spectroscopy of individual objects

With the introduction of single-molecule spectroscopy it was immediately realised that studying molecules and molecular aggregates individually opens up a completely new approach to elucidate information commonly washed out by the ensemble average process. In contrast with ensemble experiments, this technique permits us to determine the whole distribution of parameters rather than their moments. This allows a more direct verification of theoretical models without the need to average over (unknown) distributions to calculate observables. Here we illustrate how single-molecule spectroscopy can be utilised to circumvent the classical diffraction limit of microscopy and show an investigation of the electronic structure of pigment protein complexes that are relevant for bacterial photosynthesis.     

傅里叶变换红外光谱谱图排疑分析

阐述了傅里叶变换红外光谱的基本原理及特点,并通过利用红外光谱图对未知气体进行分析判定的方法,探讨了这一方法在化学事故应急监测中的应用.