Emission and Laser-Induced Fluorescence Spectroscopy of Laser-Ablated Titanium Plume

1999 ◽  
Author(s):  
Schubert S. Chu ◽  
Costas P. Grigoropoulos
Keyword(s):  
Time Of Flight ◽  
Laser Induced Fluorescence ◽  
Spectroscopic Techniques ◽  
Wide Range ◽  
Optical Time ◽  
Background Gas ◽  
Spectrally Resolved ◽  
Deposited Film

Abstract Pulsed laser deposition (PLD) of thin films has evolved into a well-recognized technique for a wide range of materials and in a variety of devices. There is great interest in the energy characterization of the ablated plume because this is a key parameter in determining the quality of the deposited film. Spectroscopic techniques, such as optical time-of-flight (TOF,) emission spectroscopy, and laser-induced-fluorescence (LIF) are excellent methods for this purpose since they offer temporal and spatial resolution as well as the capability of distinguishing different species. The effects of laser fluence and background gas pressure on the kinetic energies of the ablated species were found by the optical time-of flight technique and by emission imaging. Furthermore, laser-induced-fluorescence was employed for spectrally resolved imaging. The results provide additional data on the kinetic energy and the distribution of neutral titanium. The axial velocity of neutral titanium was found to be as high as 2 × 104 m/s. The distribution of species within the plume was also determined.

Determination of Kinetic Energy Distribution in a Laser-Ablated Titanium Plume by Emission and Laser-Induced Fluorescence Spectroscopy

2000 ◽  
Vol 122 (4) ◽  
pp. 771-775 ◽  
Author(s):  
S. S. Chu ◽  
C. P. Grigoropoulos
Keyword(s):  
Kinetic Energy ◽  
Time Of Flight ◽  
Laser Induced Fluorescence ◽  
Spectroscopic Techniques ◽  
Wide Range ◽  
Excellent Method ◽  
Optical Time ◽  
Background Gas ◽  
Spectrally Resolved

Pulsed laser deposition (PLD) of thin films has become a viable technique for a wide range of applications over the last few decades. As kinetic energy of the ablated plume is an important parameter in determining the quality of the film; consequently there is great interest in nonintrusive evaluation of the plume kinetic energy. Spectroscopic techniques such as optical time-of-flight (TOF) utilizes emission spectroscopy or laser-induced-fluorescence (LIF) and is an excellent method for this purpose since they offer temporal and spatial resolution as well as the capability of distinguishing different species. In this paper, the effects of laser fluence and background gas pressure on the kinetic energies of the ablated species are found by the optical time-of flight technique and by emission imaging. Laser-induced-fluorescence is employed for spectrally resolved imaging. The axial velocity of neutral titanium is found to be as high as 2×104 m/s. The distribution of species within the plume is also determined. [S0022-1481(00)01704-7]

scholarly journals The Calibration Home Base for Imaging Spectrometers

2016 ◽  
Vol 2 ◽  
Author(s):  
Johannes Felix Simon Brachmann ◽  
Andreas Baumgartner ◽  
Peter Gege
Keyword(s):  
Wavelength Range ◽  
Stray Light ◽  
Third Party ◽  
Home Base ◽  
Geometric Calibration ◽  
Wide Range ◽  
Along Track ◽  
Near Future

The Calibration Home Base (CHB) is an optical laboratory designed for the calibration of imaging spectrometers for the VNIR/SWIR wavelength range. Radiometric, spectral and geometric calibration as well as the characterization of sensor signal dependency on polarization are realized in a precise and highly automated fashion. This allows to carry out a wide range of time consuming measurements in an ecient way. The implementation of ISO 9001 standards in all procedures ensures a traceable quality of results. Spectral measurements in the wavelength range 380–1000 nm are performed to a wavelength uncertainty of +- 0.1 nm, while an uncertainty of +-0.2 nm is reached in the wavelength range 1000 – 2500 nm. Geometric measurements are performed at increments of 1.7 µrad across track and 7.6 µrad along track. Radiometric measurements reach an absolute uncertainty of +-3% (k=1). Sensor artifacts, such as caused by stray light will be characterizable and correctable in the near future. For now, the CHB is suitable for the characterization of pushbroom sensors, spectrometers and cameras. However, it is planned to extend the CHBs capabilities in the near future such that snapshot hyperspectral imagers can be characterized as well. The calibration services of the CHB are open to third party customers from research institutes as well as industry.

scholarly journals Effects of gas–wall interactions on measurements of semivolatile compounds and small polar molecules

2019 ◽  
Vol 12 (6) ◽  
pp. 3137-3149 ◽  
Author(s):  
Xiaoxi Liu ◽  
Benjamin Deming ◽  
Demetrios Pagonis ◽  
Douglas A. Day ◽  
Brett B. Palm ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Transmission Efficiency ◽  
Polar Molecules ◽  
Ionization Mass ◽  
Atmospheric Measurements ◽  
Wide Range ◽  
Teflon Tubing ◽  
Gas Interactions

Abstract. Recent work has quantified the delay times in measurements of volatile organic compounds (VOCs) caused by the partitioning between the gas phase and the surfaces of the inlet tubing and instrument itself. In this study we quantify wall partitioning effects on time responses and transmission of multifunctional, semivolatile, and intermediate-volatility organic compounds (S/IVOCs) with saturation concentrations (C∗) between 100 and 104 µg m−3. The instrument delays of several chemical ionization mass spectrometer (CIMS) instruments increase with decreasing C∗, ranging from seconds to tens of minutes, except for the NO3- CIMS where it is always on the order of seconds. Six different tubing materials were tested. Teflon, including PFA, FEP, and conductive PFA, performs better than metals and Nafion in terms of both delay time and transmission efficiency. Analogous to instrument responses, tubing delays increase as C∗ decreases, from less than a minute to >100 min. The delays caused by Teflon tubing vs. C∗ can be modeled using the simple chromatography model of Pagonis et al. (2017). The model can be used to estimate the equivalent absorbing mass concentration (Cw) of each material, and to estimate delays under different flow rates and tubing dimensions. We also include time delay measurements from a series of small polar organic and inorganic analytes in PFA tubing measured by CIMS. Small polar molecules behave differently than larger organic ones, with their delays being predicted by their Henry's law constants instead of their C∗, suggesting the dominance of partitioning to small amounts of water on sampling surfaces as a result of their polarity and acidity properties. PFA tubing has the best performance for gas-only sampling, while conductive PFA appears very promising for sampling S/IVOCs and particles simultaneously. The observed delays and low transmission both affect the quality of gas quantification, especially when no direct calibration is available. Improvements in sampling and instrument response are needed for fast atmospheric measurements of a wide range of S/IVOCs (e.g., by aircraft or for eddy covariance). These methods and results are also useful for more general characterization of surface–gas interactions.

scholarly journals Effects of Gas-Wall Interactions on Measurements of Semivolatile Compounds and Small Polar Molecules

2019 ◽  
Author(s):  
Xiaoxi Liu ◽  
Benjamin Deming ◽  
Demetrios Pagonis ◽  
Douglas A. Day ◽  
Brett B. Palm ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Transmission Efficiency ◽  
Polar Molecules ◽  
Ionization Mass ◽  
Atmospheric Measurements ◽  
Wide Range ◽  
Teflon Tubing ◽  
Gas Interactions

Abstract. Recent work has quantified the delay times in measurements of volatile organic compounds (VOCs) caused by the partitioning between the gas phase and the surfaces of the inlet tubing and instrument itself. In this study we quantify wall partitioning effects on time responses and transmission of multi-functional, semivolatile and intermediate-volatility organic compounds (S/IVOCs) with saturation concentrations (C*) between 100 and 104 µg m−3. The instrument delays of several chemical ionization mass spectrometer (CIMS) instruments increase with decreasing C*, ranging from seconds to tens of minutes, except for the NO3−-CIMS where it is always on the order of seconds. Six different tubing materials were tested. Teflon, including PFA, FEP, and conductive PFA, performs better than metals and Nafion in terms of both delay time and transmission efficiency. Analogous to instrument responses, tubing delays increase as C* decreases, from less than a minute to > 100 min. The delays caused by Teflon tubing vs. C* can be modeled using the simple chromatography model of Pagonis et al. (2017). The model can be used to estimate the equivalent absorbing mass concentration (Cw) of each material, and to estimate delays under different flow rates and tubing dimensions. We also include time delay measurements from a series of small polar organic and inorganic analytes in PFA tubing measured by CIMS. Small polar molecules behave differently than larger organic ones, with their delays being predicted by their Henry’s law constants instead of their C*, suggesting the dominance of partitioning to small amounts of water on sampling surfaces as a result of their polarity and acidity properties. PFA tubing has the best performance for gas-only sampling, while conductive PFA appears very promising for sampling S/IVOCs and particles simultaneously. The observed delays and low transmission both affect the quality of gas quantification, especially when no direct calibration is available. Improvements in sampling and instrument response are needed for fast atmospheric measurements of a wide range of S/IVOCs (e.g., by aircraft or for eddy covariance). These methods and results are also useful for more general characterization of surface/gas interactions.

scholarly journals Interface Refinement of Low-to-Medium Resolution Cryo-EM Complexes using HADDOCK2.4

2021 ◽  
Author(s):  
Tim Neijenhuis ◽  
Siri C. van Keulen ◽  
Alexandre M.J.J. Bonvin
Keyword(s):  
Protein Complexes ◽  
Protein Assemblies ◽  
Cellular Processes ◽  
Protein Interfaces ◽  
Density Maps ◽  
Medium Resolution ◽  
Wide Range ◽  
Multimeric Protein

A wide range of cellular processes require the formation of multimeric protein complexes. The rise of cryo-electron microscopy (cryo-EM) has enabled the structural characterization of these protein assemblies. The produced density maps can, however, still suffer from limited resolution, impeding the process of resolving structures at atomic resolution. In order to solve this issue, monomers can be fitted into low-to-medium resolution maps. Unfortunately, the produced models frequently contain atomic clashes at the protein-protein interfaces (PPIs) as intermolecular interactions are typically not considered during monomer fitting. Here, we present a refinement approach based on HADDOCK2.4 to remove intermolecular clashes and optimize PPIs. A dataset of 14 cryo-EM complexes was used to test eight protocols. The best performing protocol, consisting of a semi-flexible simulated annealing refinement with restraints on the centroids of the monomers, was able to decrease intermolecular atomic clashes by 98% without significantly deteriorating the quality of the cryo-EM density fit.

The characterization of volatile molecular substances

1993 ◽  
Vol 443 (1918) ◽  
pp. 313-332 ◽  
Keyword(s):  
Subjective Evaluation ◽  
Sensor Arrays ◽  
Intrinsic Property ◽  
Wide Range ◽  
The Laplace Transform ◽  
Molecular Substances ◽  
Definition Of ◽  
Enclosed Space

Diffusion for gaseous sources comprising more than one type of substance is examined to show how relative concentrations change with time and distance. The large variations which are predicted make nonsense of the popular assumption that odour or smell is an intrinsic property of the source material. However, some characterization of volatile chemical substances is needed. It is shown that this is possible by creating a uniform and stable atmosphere after the relapse of sufficient time by introducing the gas mixture into an enclosed space. In this investigation the situation is analysed for a spherical enclosure using Fourier analysis techniques for the long timescale behaviour and the Laplace transform for the short timescale solution. The measurement of odours via the response of sensor arrays within a spherical enclosure is considered and a proposal is made for utilizing such an enclosure in a definition of volatile molecular substances (analogous to biological ‘smell’). The conditions for optimum compatibility between an array of sensors and a set of calibrands are discussed and the practical means of effecting such measurements are considered in relation to known types of sensor. It is concluded that the quality of volatile molecular substances is definable and measurable down to very low gas concentrations in air: probably below 10 parts per billion for a wide range of gas mixtures unconstrained by such limitations associated with a biological nose such as toxicity, temperature and subjective evaluation.

Applications of Spectroscopic Techniques for Polymer Nanocomposite Characterization

2021 ◽  
Author(s):  
MARYAM BATOOL ◽  
Muhammad Nouman Haider ◽  
Tariq Javed
Keyword(s):  
Solid State ◽  
Molecular Characterization ◽  
Polymer Nanocomposite ◽  
Hydroxyl Groups ◽  
Spectroscopic Techniques ◽  
Characterization Techniques ◽  
Wide Range ◽  
Polymer Fillers ◽  
Principle Objective

Abstract During past decades, spectroscopic techniques find wide range of applications ranging from biological applications to the measurement of chemical composition and characterization of variety of substances i.e., polymers, nanocomposites etc. Nanocomposites are emerging and growing materials having wide variety of uses. To study the characteristic properties, characterize, and development of new materials using polymer nanocomposites, several molecular characterization techniques are available and are in use today. Principle objective of this review is to summarize the knowledge in current characterization techniques and to study the applications of fluorescence, solid-state nuclear magnetic resonance (NMR), infrared, besides Raman molecular characterization techniques for characterization of polymers, filler, and composites. Fluorescence technique did not provide detailed analysis of materials while solid-state NMR spectroscopy determine silanol hydroxyl groups at the silica exterior in addition to their interactions with polymer and polymer-filler interfacial interactions (via relaxation time). For characterization of various kinds of functional groups in polymer/ fillers, infrared spectroscopy employed. While Raman spectroscopy finds extensive applications for analysis of carbon-based materials. Novelty of this review is that till yet very few review papers have been published which briefly describe all these mentioned techniques along their applications in a very simple and an effective way.

scholarly journals Characterization of ‘Castellana’ Virgin Olive Oils with Regard to Olive Ripening

2018 ◽  
Vol 28 (1) ◽  
pp. 48-57 ◽  
Author(s):  
Carmen Mena ◽  
Alejandra Z. González ◽  
Raúl Olivero-David ◽  
María Ángeles Pérez-Jiménez
Keyword(s):  
Olive Oil ◽  
Virgin Olive Oil ◽  
Quality Parameters ◽  
Virgin Olive Oils ◽  
Olive Oils ◽  
Wide Range ◽  
Sensorial Quality ◽  
Olive Ripening

The production of high-quality virgin olive oil from traditional olive (Olea europaea L.) varieties with peculiar and differential characteristics is of great interest for the olive oil market. ‘Castellana’ is an autochthonous variety mainly located in the center of Spain. The aims of this study were 1) the characterization of ‘Castellana’ virgin olive oils and 2) the evaluation of the influence of fruit ripening degree on the oil quality to establish an optimum harvest time for ‘Castellana’ olives. A wide range of physicochemical and sensorial quality parameters were assayed in oils produced at four harvest times during three crop seasons. ‘Castellana’ oils could be classified into the extra virgin category at all ripening degrees studied. This variety provides well-balanced oils from the sensorial point of view with an optimum chemical composition. Nevertheless, fruit maturation had a strong effect in various quality parameters, especially total phenol content, total tocopherol content, sensorial quality, and to a lesser extent in fatty acid composition. Loss of antioxidants and decrease in sensorial quality take place during olive ripening, reducing the nutritional, sensorial, and commercial quality of virgin olives oils as the harvest is delayed. Results suggest that the production of optimal extra virgin olive oil requires that ‘Castellana’ olives should be harvested from the middle of November to the middle of December, coinciding with a ripening index between 3.1 and 4.1. These results are of great importance to the olive oil industry for improving the quality of virgin olive oils produced from ‘Castellana’.

Fabrication and Characterization of Organic Semiconductor Based Gas Sensor

2009 ◽  
Vol 421-422 ◽  
pp. 344-347
Author(s):  
Munirah Atique ◽  
Ghulam Shabbir ◽  
Mazhar Mehmood
Keyword(s):  
Organic Semiconductor ◽  
Conduction Mechanism ◽  
Gas Sensing ◽  
Sensor Film ◽  
Sensing Applications ◽  
Ag Electrodes ◽  
Fabrication And Characterization ◽  
Deposited Film

Thin films of organic semiconductor based azo-dye, OD 25, of the average thickness, 750 ± 10 nm, were desposited successfully on the glass substrate for gas sensing applications. Electrical conductivity was of the film as measured by impedance spectroscopy, showed an increase with frequency that was attributed to non-metallic nature of the film. Moreover, single conduction mechanism and negligible contact resistance showed good quality of the sensor film. Deposited film with Al and Ag electrodes showed good conductance when exposed to water and ethanol vapors.

Investigation of Cytotoxic Constituents from Seed Pulp of Entada Phaseoloides and Metabolite Profiling Using UPLC-QTOF-MSE

2020 ◽  
Author(s):  
P Pavan Kumar ◽  
Bandi Siva ◽  
Kumar Katragunta ◽  
Supriya D Beedkar ◽  
Sistla Ramakrishna ◽  
...  
Keyword(s):  
Liquid Chromatography ◽  
Time Of Flight ◽  
Bioactive Constituents ◽  
Isolation And Identification ◽  
Phytochemical Study ◽  
Crude Extracts ◽  
Wide Range ◽  
Entada Phaseoloides ◽  
Comprehensive Characterization

Abstract Background Entada phaseoloides (Linn.) Merr. (Family: Fabaceae) is a well-known, traditional, medicinal plant that has been extensively used in the Ayurvedic system of medicine for centuries to combat a wide range of ailments. Objective The goal of this work was to investigate the bioactive constituents from n-butanol extracts of Entada. phaseoloides and develop a method for the comprehensive characterization of saponins using liquid chromatography with an electrospray ionization quadrupole time-of-flight mass spectrometer (LC-ESI-QTOF-MS). Methods A hyphenated technique, ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS/MS), has been proposed to integrate LC and MS together with NMR for structural elucidation. This method allowed comprehensive characterization of saponin glycosides from E. phaseoloides based on their MS/MS fragmentation study. Results The phytochemical study of E. phaseoloides resulted in the isolation and identification of three bio-active constituents. Further, the UPLC-QTOF-MS/MS method led the structure elucidation of saponin constituents directly from crude extracts via comparison of the exact molecular masses from their MS/MS spectra. Identified common fragments m/z 648, 630, 498, 366, and 204 were used for the screening of saponin components. Conclusions The present study summarizes the isolation and identification of bio-compounds from n-butanol extract and the demonstration of UPLC-QTOF-MS/MS analysis for the characterization of compounds in complex crude extracts. To the best of our knowledge, this is the first systematic study in structural characterization on complex saponins and other metabolites from crude extract of E. phaseoloides using UPLC-ESI-QTOF-MSE. Highlights Rapid analysis and characterizations of three new saponins from E. phaseoloides using UPLC-ESI-QTOF-MSE were tentatively identified based on the mass fragmentation study.

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