In-situ Monitoring and Determination of AlGaAs Composition During MOCVD Growth

2012 ◽  
Vol 33 (9) ◽  
pp. 985-990
Author(s):  
王鹏程 WANG Peng-cheng ◽  
徐华伟 XU Hua-wei ◽  
张金龙 ZHANG Jin-long ◽  
宁永强 NING Yong-qiang
Keyword(s):  
In Situ Monitoring ◽  
Mocvd Growth

In-situ monitoring and control for MOCVD growth of AlGaAs and InGaAs

1997 ◽  
Vol 26 (10) ◽  
pp. 1145-1153 ◽  
Author(s):  
A. Kussmaul ◽  
S. Vernon ◽  
P. C. Colter ◽  
R. Sudharsanan ◽  
A. Mastrovito ◽  
...  
Keyword(s):  
In Situ Monitoring ◽  
Monitoring And Control ◽  
Mocvd Growth ◽  
And Control

Rapid Determination of Organic Matter Fractions by Ozonation Chemiluminescence

2012 ◽  
Vol 468-471 ◽  
pp. 2842-2848 ◽  
Author(s):  
Yan Liu ◽  
Ping Ping Fan ◽  
Guang Li Hou ◽  
Ji Chang Sun ◽  
Yan Cheng ◽  
...  
Keyword(s):  
Organic Matter ◽  
Rapid Determination ◽  
In Situ Monitoring ◽  
Global Ocean ◽  
Sediment Chemistry ◽  
Marine Biogeochemistry ◽  
Organic Matter Fractions ◽  
Soluble Fractions

Understanding marine biogeochemistry requires a network of global ocean in situ monitoring of various parameters on different scales in time and space. Among the various parameters involved in marine biogeochemistry, sediment chemistry is most important, and the organic matter fractions are the dominate factor in this parameter. However, classical methods of determining organic matter fractions consume a great deal of time and labor. In addition, some of these methods can produce high levels of pollution and are therefore not suitable for in situ studies. This study explored a method of rapid determination of organic matter fractions by ozonation chemiluminescence. In this method, the organic matter was separated into extractives, acid soluble fractions and acid insoluble fractions (AIF) using the classical method and then oxidized by ozone. The ozonation chemiluminescence characteristics of eight samples were subsequently used to set up a model to predict the concentrations of organic matter fractions. The model was tested using nine other organic samples and the results showed that it provided a better fit for the predicted acid soluble fractions. This study is the first to demonstrate the use of ozonation chemiluminescence for rapid determination of organic matter fractions; however, further study is required to enable its universal use.

scholarly journals Luminol Doped Silica-Polymer Sensor for Portable Organic Amino Nitrogen and Ammonium Determination in Water

Separations ◽  
2021 ◽  
Vol 8 (9) ◽  
pp. 149
Author(s):  
Sara Bocanegra-Rodríguez ◽  
Carmen Molins-Legua ◽  
Pilar Campíns-Falcó
Keyword(s):  
Limit Of Detection ◽  
Nitrogen Concentration ◽  
Amino Nitrogen ◽  
In Situ Monitoring ◽  
Luminescence Signal ◽  
The Matrix ◽  
Ammonium Determination ◽  
Portable Sensor

We propose a portable sensor, obtained by embedding luminol into the tetraethylorthosilicate/trietoxymethylsilane (TEOS/MTEOS) composite, for the quantitative determination of organic amino nitrogen and ammonium in water with the goal of achieving low levels of concentration. The method is based on the reaction between amino nitrogen compounds and hypochlorite to produce chloramino derivatives. Then, the remaining hypochlorite reacts with luminol sensor by producing a luminescence signal, which was measured by using a portable luminometer, being inversely proportional to nitrogen concentration. The liberation of the luminol from sensor is higher than 90% and the sensor is stable for at least a week at room temperature. This portable method was successfully validated and applied to the analysis of several real waters: fountain, river transition, lagoon, and seawater with recovery values between 92% and 112%, which indicated that the matrix effect was absent. The achieved limit of detection was around 10 µg·L−1, expressed as N. This sensor allows in situ monitoring owing to its simplicity, rapidity, and portability.

scholarly journals Sequential Collinear Photofragmentation and Atomic Absorption Spectroscopy for Online Laser Monitoring of Triatomic Metal Species

Sensors ◽  
2020 ◽  
Vol 20 (2) ◽  
pp. 533 ◽  
Author(s):  
Jan Viljanen ◽  
Kim Kalmankoski ◽  
Victor Contreras ◽  
Jaakko K. Sarin ◽  
Tapio Sorvajärvi ◽  
...  
Keyword(s):  
Atomic Absorption ◽  
Gas Phase ◽  
Absorption Spectroscopy ◽  
Atomic Absorption Spectroscopy ◽  
Limit Of Detection ◽  
In Situ Monitoring ◽  
Metal Species ◽  
Chemical Reaction Kinetics

Industrial chemical processes are struggling with adverse effects, such as corrosion and deposition, caused by gaseous alkali and heavy metal species. Mitigation of these problems requires novel monitoring concepts that provide information on gas-phase chemistry. However, selective optical online monitoring of the most problematic diatomic and triatomic species is challenging due to overlapping spectral features. In this work, a selective, all-optical, in situ gas-phase monitoring technique for triatomic molecules containing metallic atoms was developed and demonstrated with detection of PbCl2. Sequential collinear photofragmentation and atomic absorption spectroscopy (CPFAAS) enables determination of the triatomic PbCl2 concentration through detection of released Pb atoms after two consecutive photofragmentation processes. Absorption cross-sections of PbCl2, PbCl, and Pb were determined experimentally in a laboratory-scale reactor to enable calibration-free quantitative determination of the precursor molecule concentration in an arbitrary environment. Limit of detection for PbCl2 in the laboratory reactor was determined to be 0.25 ppm. Furthermore, the method was introduced for in situ monitoring of PbCl2 concentration in a 120 MWth power plant using demolition wood as its main fuel. In addition to industrial applications, the method can provide information on chemical reaction kinetics of the intermediate species that can be utilized in reaction simulations.

In situ monitoring of the MOCVD growth of CdS/CdTe

2000 ◽  
Vol 221 (1-4) ◽  
pp. 117-123 ◽  
Author(s):  
S.J.C Irvine ◽  
A Hartley ◽  
A Stafford
Keyword(s):  
In Situ Monitoring ◽  
Mocvd Growth

In-situ monitoring of chemical reactions in MOCVD growth of ZnSe

1986 ◽  
Vol 79 (1-3) ◽  
pp. 363-370 ◽  
Author(s):  
J.I. Davies ◽  
M.J. Parrott ◽  
J.O. Williams
Keyword(s):  
Chemical Reactions ◽  
In Situ Monitoring ◽  
Mocvd Growth

Determination of Nitrate Based on the Least Area Value Model in the Ocean

2013 ◽  
Vol 726-731 ◽  
pp. 66-73
Author(s):  
Ling Ling Shen ◽  
Shu Ming Ye ◽  
Hang Chen
Keyword(s):  
Dark Current ◽  
Field Measurements ◽  
In Situ Monitoring ◽  
Multiple Observations ◽  
The Stability ◽  
Value Model ◽  
Least Area ◽  
Accuracy And Stability

In situ monitoring of nitrate in respect of improvement of accuracy becomes more and more important. The direct spectrophotometer analysis of aqueous nitrates is a simple analytic procedure but prone to interferences. In order to solve this problem, the Least Area Value (LAV) Model for in situ determining nitrate in the ocean is reported. The absorbance response of the LAV model varies linearly with concentrations.Calculations of it are in excellent much higher accuracy than conventional measurement models.And more, it solves the problem without the need to measure the dark current first. This eliminated errors due to changes in the dark current during periods shortly after the instrument was turned on. The noise is nearly random and significant reductions in the detection limit are possible by averaging multiple observations in this model. The measurements were directly taken after dilution of the samples between 0.1μmol/l and 400μmol/l.The model was checked on and applied to real samples .The results show that this approach is suitable for routine field measurements of nitrate, which has achieved the precision of 99% and the stability of 99.5%. The model is simple, rugged. The precision, accuracy and stability of the concentrations are sufficiently used to support for many studies.

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