Laser-Induced Photochemical Reactions of Methanol, Ethanol, 1-Propanol, and 2-Propanol

1988 ◽  
Vol 42 (7) ◽  
pp. 1268-1273 ◽  
Author(s):  
R. A. Johnson ◽  
A. E. Stanley
Keyword(s):  
Fourier Transform ◽  
Carbon Dioxide Laser ◽  
Continuous Wave ◽  
Irradiation Time ◽  
Photochemical Reactions ◽  
Output Line ◽  
Time Intervals ◽  
Consecutive Reaction ◽  
Initial Reactant ◽  
Consecutive Reactions

This study focuses on the carbon dioxide laser-induced excitation and resultant dissociation of several members of a group of carbon-oxygen (C-O)-containing molecules, the alcohols methanol, ethanol, 1-propanol, and 2-propanol. The tunable continuous-wave infrared (cw) laser provides the energy of activation necessary for dissociation to occur after absorption into the C-O stretching fundamentals of the alcohols. Chemical reactions were monitored with the use of Fourier transform infrared spectroscopy, also used for identification of end products. After irradiation, ethanol and 1-propanol each yielded acetaldehyde. The products of the dissocation of methanol were carbon monoxide, formaldehyde, and hydrogen. The formaldehyde then reacted with excess methanol to produce methoxymethanol. Fourier transform interferograms were collected at specific time intervals, thus monitoring any consecutive reactions that occurred after the irradiation. For methanol, laser parameters such as output line frequency and power as well as irradiation time were varied. The effect of initial reactant pressure on the laser-induced dissociation of methanol was evaluated. Only methanol underwent a consecutive reaction. Hydrocarbon fragments were also observed from ethanol, 1-propanol, and 2-propanol. Methane, ethene, and ethyne were produced from ethanol. Propene, ethene, and methane were produced from 1-propanol, and methane and propene from 2-propanol. The products observed in some instances were different from those reported in the literature for pyrolytic and pulsed laser studies. The results from these investigations are compared with results from other similar compounds and similar techniques.

Zur Anwendimg vpm Extinktionsdiagrammen bei der kinetischen Analyse von Photoreaktionen / Kinetic Analysis of Photochemical Reactions Using Extinction Diagrams

1972 ◽  
Vol 27 (11) ◽  
pp. 1354-1359 ◽  
Author(s):  
Heinz Mauser ◽  
Volker Starrock ◽  
Hans-Joachim Niemann
Keyword(s):  
Quantum Yield ◽  
Kinetic Analysis ◽  
Rate Constant ◽  
Extinction Coefficient ◽  
Photochemical Reactions ◽  
Experimental Results ◽  
Quantum Yields ◽  
Reaction Step ◽  
Consecutive Reaction ◽  
Consecutive Reactions

The reaction of anthraquinone in alkaline methanol irradiated with 313 nm light is followed spectrophotometrically. The experimental results point to an irreversible consecutive reaction A → B → C. Since the concentration and extinction coefficient of the intermediate are unknown, the partial quantum yield cannot be calculated. A new method is described for calculation of the concentration of the unknown intermediate using the extinction diagram. It is suitable for consecutive reactions, if the rate constant of the first reaction-step is very great as compared with that of the second. Now the partial quantum yields of the two reaction-steps can be calculated.

FT-IR Analysis of the Laser-Induced Dissociation of Methylphosphonic Difluoride

1995 ◽  
Vol 49 (4) ◽  
pp. 478-481
Author(s):  
Ann E. Stanley
Keyword(s):  
Carbon Dioxide ◽  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Reaction Mechanism ◽  
Carbon Dioxide Laser ◽  
Continuous Wave ◽  
Phosphorus Compounds ◽  
Product Analysis ◽  
Ft Ir ◽  
Ir Analysis

The output of a continuous-wave carbon dioxide laser was used successfully for the dissociation of methylphosphonic difluoride. End product analysis using Fourier transform infrared spectroscopy revealed that the phosphorus-to-carbon bond was cleaved, yielding the products methane, ethene, ethyne, hydrophosphoryl difluoride, and a mixture of phosphorus compounds. These results are presented and discussed. The dissociation was optimized. A reaction mechanism of the dissociation is suggested.

Isolating solitons from the resonant continuous wave by using nonlinear Fourier transform

2021 ◽  
Author(s):  
Yutian Wang ◽  
Songnian Fu ◽  
Chi Zhang ◽  
Xiahui Tang ◽  
Jian Kong ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Continuous Wave ◽  
Nonlinear Fourier Transform

Microstructure Morphology and Mechanical Properties of Steel 30CrMnSiNi2A Irradiated by Continuous Wave Laser

2014 ◽  
Vol 809-810 ◽  
pp. 369-376
Author(s):  
Tao Tao Wu ◽  
Li Jun Wang ◽  
Cheng Hua Wei ◽  
Chun Xu Pan ◽  
Lin Zhu Chen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Laser Irradiation ◽  
Continuous Wave ◽  
Solid Phase ◽  
Irradiation Time ◽  
Coupling Efficiency ◽  
Temperature History ◽  
Brittle Layer ◽  
Microstructure Morphology ◽  
Morphology And Mechanical Properties

Steel 30CrMnSiNi2A slices were irradiated by a continuous wave fiber laser beam with the intensity of 14.5W/cm2. Alloy samples with various temperature processes were obtained by changing the laser irradiation time, irradiation times and atmosphere environment. X-ray diffraction, scanning electron microscope, energy dispersive spectrometer and nanoindentation system were employed to characterize their microstructure morphology and mechanical properties. Three layers were observed in the samples fracture, namely oxide film, hard brittle layer and alloy substrate. The hard brittle layer had a higher hardness and a lower toughness compared with the base metal. Referring to the temperature history, we deemed that the surface oxidation and the solid phase transformation were the main factors which changed laser coupling efficiency. The results also illuminated the correlation between the microstructure morphology and the response to laser irradiation of the samples.

High-Precision Continuous-Wave Terahertz Spectroscopy Based on a Photomixing Technique for Identifying Pearls

2019 ◽  
Vol 73 (12) ◽  
pp. 1388-1393
Author(s):  
Chihoon Kim ◽  
Taeksoo Ji
Keyword(s):  
Optical Coherence Tomography ◽  
Fourier Transform ◽  
Ir Spectroscopy ◽  
Continuous Wave ◽  
Terahertz Spectroscopy ◽  
Thz Spectroscopy ◽  
Ft Ir ◽  
Thz Absorption ◽  
Ft Ir Spectroscopy ◽  
Cultured Pearls

We present the accurate terahertz spectra of between imitation and cultured pearls using continuous-wave terahertz (CW-THz) spectroscopy. Using Fourier transform infrared (FT-IR) spectroscopy and optical coherence tomography (OCT) measurements, cultured pearls can be distinguished from imitation pearls by observing distinct absorption peaks and discriminative boundaries. The THz absorption spectra up to 0.3 THz obtained from CW-THz spectroscopy show several absorption peaks at specific frequencies with the cultured pearls but no peaks with the imitation pearls, which results from the existence of the nacre polymorph of cultured pearls. Hence, it is expected that the CW-THz system proposed herein will be applicable to fast, nondestructive spectrum analysis including pearl identification.

A flexible, efficient and low-cost experimental platform for FMCW radars

Sensor Review ◽  
2019 ◽  
Vol 39 (4) ◽  
pp. 495-503 ◽  
Author(s):  
Tao Wang ◽  
Ping Li ◽  
Mingfang Wang ◽  
DanDan Yang ◽  
Chaoyu Shi
Keyword(s):  
Fourier Transform ◽  
Continuous Wave ◽  
Low Cost ◽  
Low Frequency ◽  
Waveform Data ◽  
Content Type ◽  
Experimental Platform ◽  
Field Programmable ◽  
Health Care Applications ◽  
Measurement Experiment

Purpose This paper proposes a design of an efficient and automated experimental platform for frequency modulated continuous wave (FMCW) radars. The platform can quickly flexibly generate the waveform that meets measurement requirements and significantly improve experimental efficiency. Design/methodology/approach This platform not only includes radio frequency devices but also integrates a programmable transmitter based on field programmable gate array. By configuring the waveform data, the experimental platform can generate waveforms with adjustable parameters and realize automatic emission, reception and processing of signals. Different from traditional fast Fourier transform, this paper uses a discrete-time Fourier transform to process low-frequency signals to get more accurate results. Findings The authors demonstrate the effectiveness of the platform through a single-path cable experiment, an indoor ranging experiment by using different modulating waveforms and a speed measurement experiment. With complete functions and strong flexibility, the platform can operate effectively in various conditions and greatly improve the efficiency of research and study. Practical implications The platform can accelerate the research studies and applications of FMCW radars in the fields of automatic drive, through-wall detection and health-care applications. Originality/value Cost and functionality are taken into account in the platform, which can significantly improve the efficiency of research. The proposed signal processing method improves the accuracy while its computation complexity does not increase significantly.

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