EFFECT OF NON-ZERO EXTINCTION COEFFICIENT ON ABSTRACTION–RECOMBINATION RATE RATIOS IN PHOTOCHEMICAL SYSTEMS

1963 ◽  
Vol 41 (12) ◽  
pp. 3042-3049 ◽  
Author(s):  
H. O. Pritchard ◽  
G. O. Pritchard
Keyword(s):  
Extinction Coefficient ◽  
Recombination Rate ◽  
Rate Equations ◽  
Extinction Coefficients ◽  
Rate Expression ◽  
Diffusion Effects ◽  
Photochemical Systems ◽  
Rate Ratios

The data of Marjury and Steacie on the photolysis of acetone and acetone-d6 in the presence of H2 and D2 respectively have been re-analyzed in terms of the integrated rate equations. It is concluded that only part of the discrepancy between the results for the methyl and hydrogen reaction can be accounted for in this way.In an appendix, it is shown that for high extinction coefficients, the integrated rate expression reaches a limit which may sometimes be attainable experimentally without undue complication from diffusion effects.

scholarly journals A spectrophotometric method for determination of fluorophore-to-protein ratios in conjugates of the blue fluorophore 7-amino-4-methylcoumarin-3-acetic acid (AMCA)

1990 ◽  
Vol 38 (1) ◽  
pp. 87-94 ◽  
Author(s):  
M W Wessendorf ◽  
S J Tallaksen-Greene ◽  
R M Wohlhueter
Keyword(s):  
Acetic Acid ◽  
Optical Density ◽  
Extinction Coefficient ◽  
Spectrophotometric Method ◽  
Extinction Coefficients ◽  
Beer's Law ◽  
Beer’S Law ◽  
The Given

7-Amino-4-methylcoumarin-3-acetic acid (AMCA) has been found to be a useful fluorophore for immunofluorescence. The present study describes a spectrophotometric method for determining the ratio of moles AMCA to moles protein (or the f/p ratio) in an AMCA-conjugated IgG. The concentration of a substance absorbing light can be determined spectrophotometrically using Beer's Law: Absorbance = Concentration x Extinction coefficient. From Beer's law, one can derive the following formula for determining the f/p ratio of AMCA-IgG conjugates: f/p = (epsilon 280IgG).A350 - (epsilon 350IgG).A280/(epsilon 350AMCA).A280 - (epsilon 280AMCA).A350 where A is the optical density of the conjugate at the given wavelength and epsilon is the extinction coefficient of a substance at the wavelength specified. Using conjugates of model proteins, it was found that the extinction coefficients of the AMCA moiety of AMCA-conjugated protein were 1.90 x 10(4) at 350 nm and 8.29 x 10(3) at 280 nm. Similarly, it was found that the extinction coefficients of swine IgG were 1.56 x 10(3) at 350 nm and 1.26 x 10(5) at 280 nm. Thus, for AMCA-conjugated swine IgG: f/p = (1.26 x 10(5)).A350 - (1.56 x 10(3)).A280/(1.47 x 10(4)).A280 - (6.42 x 10(3)).A350 [corrected]. Based on this formula, the f/p ratios of some AMCA-IgG conjugates useful for immunohistochemistry have been found to range between 6 and 24.

Extinction Coefficient of Plasmonic Nickel Sulfide Nanocrystals and Gold-Nickel Sulfide Core-Shell Nanoparticles

2018 ◽  
Vol 233 (1) ◽  
pp. 3-14 ◽  
Author(s):  
Rasmus Himstedt ◽  
Dominik Hinrichs ◽  
Dirk Dorfs
Keyword(s):  
Extinction Coefficient ◽  
Nickel Sulfide ◽  
Molar Extinction Coefficient ◽  
Localized Surface Plasmon ◽  
Core Shell ◽  
Electromagnetic Spectrum ◽  
Shell Nanoparticles ◽  
Extinction Coefficients ◽  
Optical Applications ◽  
Core Shell Nanoparticles

Abstract In the presented work, the molar extinction coefficient of plasmonic heazlewoodite (Ni3S2) nanoparticles and Au-Ni3S2 core-shell nanoparticles is determined for the first time. The results are compared to analogously determined extinction coefficients of pure Au nanocrystals (NCs), which themselves correlate very well with existing literature on the subject. The measured extinction coefficients at the localized surface plasmon resonance (LSPR) maximum wavelength of nickel sulfide particles are similar to the values of equally sized Au NCs. Therefore, considering the lower cost of the heazlewoodite material, it could be a reasonable alternative for optical applications of nanoparticles showing a LSPR in the visible regime of the electromagnetic spectrum. Furthermore, this study shows, that by growing a Ni3S2 shell onto a pure Au nanocrystal a highly tuneable optical material with variable LSPR frequency and molar extinction coefficient is obtained.

Thermal Radiation in Silica Aerogel and its Composite Insulation Materials

2011 ◽  
Author(s):  
Gaosheng Wei ◽  
Yusong Liu ◽  
Xinxin Zhang ◽  
Xiaoze Du
Keyword(s):  
Thermal Radiation ◽  
Extinction Coefficient ◽  
Silica Aerogel ◽  
Extinction Coefficients ◽  
Ceramic Fibre ◽  
Insulation Materials ◽  
Hot Strip ◽  
Aerogel Composite ◽  
Infrared Spectrometer ◽  
Spectral Extinction Coefficient

This paper engages in experimental measurements on thermal radiative transfer in silica aerogel and its composite insulation materials (xonotlite-aerogel composite and ceramic fibre-aerogel composite). The samples of silica aerogel, xonotlite-type calcium silicate, and ceramic fibre insulation materials are all considered as a semi-transparent medium capable of absorbing, emitting and scattering thermal radiation. The spectral transmittances are then measured at different infrared wavelengths ranging from 2.5 to 25μm with a Fourier transform infrared spectrometer (FTIR), and subsequently used to determine the specific spectral extinction coefficient and the specific Rossland mean extinction coefficient of the sample. The radiative conductivities deduced from the overall thermal conductivities measured with the transient hot-strip (THS) method are compared with the predictions from the diffusion approximation by using the measured spectral extinction coefficient. The results show that the spectral extinction coefficients of the samples are strongly dependent on the wavelength, particularly in the short wavelength regime (<10μm). The total Rossland mean extinction coefficients of the samples are all decreasing with the temperature increasing. The radiative conductivities are found almost proportional to the cubic temperature, and decreases as the sample density increases.

scholarly journals A Minimum Variance Method for Lidar Signal Inversion

2014 ◽  
Vol 31 (2) ◽  
pp. 468-473 ◽  
Author(s):  
Andreja Sušnik ◽  
Heidi Holder ◽  
William Eichinger
Keyword(s):  
Boundary Condition ◽  
Extinction Coefficient ◽  
Minimum Variance ◽  
Lidar Data ◽  
Ambient Atmosphere ◽  
Lidar Signal ◽  
Extinction Coefficients ◽  
Minimum Variance Method ◽  
Time Scan ◽  
Signal Inversion

Abstract A method for the inversion of elastic lidar data is proposed that determines the value of the extinction coefficient to be used as a boundary condition, by minimizing the variance of the extinction coefficients in a delimited region. The method works well for single-component atmospheres, where the delimited region contains aerosols from a single distribution of concentrations. For situations where there may be two or more distributions (e.g., a smoke plume in the ambient atmosphere), the spatial regions containing each distribution must be identified and treated separately. Examples of inversions are given, including an example of a range–time scan showing the amount of shot-to-shot consistency that may be obtained from the method.

scholarly journals A Balance-by-Depth Method for the Photoelectric Measurement of the Vertical Extinction Coefficient of Water

1949 ◽  
Vol 28 (3) ◽  
pp. 751-755 ◽  
Author(s):  
W. R. G. Atkins ◽  
H. H. Poole ◽  
F. J. Warren
Keyword(s):  
Extinction Coefficient ◽  
New Method ◽  
Extinction Coefficients ◽  
Selenium Rectifier ◽  
Photoelectric Measurement ◽  
Successive Addition ◽  
Usual Formula

Vertical extinction coefficients can be determined in water using selenium rectifier cells and colour filters. The cells are connected positive to negative with a simple 0-50 microammeter across the circuit, as in the Campbell-Freeth method. There is no deflexion when the two points of contact are brought to the same potential. This is done by lowering one cell into the sea to balance the rather less sensitive deck cell. The light reaching the latter is then reduced by the successive addition of opalized plates, to approximately 60, 30, 20 and 10 %, and the sea cell is lowered further to balance at each stage. The extinctions can then be calculated by the usual formula from the known percentage transmissions and the observed depths of balance. For each plate or combination a factor may thus be obtained which when divided by the appropriate depth gives the extinction. The method is rapid in operation and the drift error can be rendered negligible. The results agree with those found by the standard potentiometer method, but the applications of the new method are necessarily more limited.

scholarly journals Stratospheric aerosol characteristics from space-borne observations: extinction coefficient and Ångström exponent

2018 ◽  
Author(s):  
Elizaveta Malinina ◽  
Alexei Rozanov ◽  
Landon Rieger ◽  
Adam Bourassa ◽  
Heinrich Bovensmann ◽  
...  
Keyword(s):  
Extinction Coefficient ◽  
Simple Relation ◽  
Stratospheric Aerosol ◽  
Accurate Information ◽  
Aerosol Extinction ◽  
Data Set ◽  
Extinction Coefficients ◽  
Angstrom Exponent ◽  
Ångström Exponent ◽  
Ångstrom Exponent

Abstract. Stratospheric aerosols are of a great importance to the scientific community, predominantly because of their role in climate, but also because accurate knowledge of aerosol characteristics is relevant for trace gases retrievals from remote sensing instruments. There are several data sets published which provide aerosol extinction coefficients in the stratosphere. However, for the instruments measuring in the limb viewing geometry, the use of this parameter is associated with uncertainties resulting from the need to assume an aerosol particle size distribution (PSD) within the retrieval process. These uncertainties can be mitigated if PSD information is retrieved. While occultation instruments provide more accurate information on the aerosol extinction coefficient, in this study, it was shown that limb instruments have better potential for the PSD retrieval, especially during the background aerosol loading periods. A data set containing PSD information was recently retrieved from SCIAMACHY limb measurements and provides two parameters of the log-normal PSD for the SCIAMACHY operational period (2002–2012). In this study, the data set is expanded by aerosol extinction coefficients and Ångström exponents calculated from the retrieved PSD parameters. Errors in the Ångström exponents and aerosol extinction coefficients are assessed using synthetic retrievals. For the extinction coefficient the resulting accuracy is within ±25 %, and for the Ångström exponent, it is better than 10 %. The recalculated SCIAMACHY aerosol extinction coefficients are compared to those from SAGE II. The differences between the instruments vary from 0 to 25 % depending on the wavelength. Ångström exponent comparison with SAGE II shows differences between 10 % at 31 km and 40 % at 18 km. Comparisons with SAGE II, however, suffer from the low amount of collocated profiles. Furthermore, the Ångström exponents obtained from the limb viewing instrument OSIRIS are used for the comparison. This comparison shows an average difference within 7 %. The time series of these differences do not show signatures of any remarkable events. Besides, the temporal behavior of the Ångström exponent in the tropics is analyzed using the SCIAMACHY data set. It is shown, that there is no simple relation between the Ångström exponent and the PSD because the same value of Ångström exponent can be obtained from an infinite number of combinations of the PSD parameters.

scholarly journals Comparison of ambient aerosol extinction coefficients obtained from in-situ, MAX-DOAS and LIDAR measurements at Cabauw

2010 ◽  
Vol 10 (12) ◽  
pp. 29683-29734 ◽  
Author(s):  
P. Zieger ◽  
E. Weingartner ◽  
J. Henzing ◽  
M. Moerman ◽  
G. de Leeuw ◽  
...  
Keyword(s):  
Optical Properties ◽  
Extinction Coefficient ◽  
In Situ Measurements ◽  
Optical Absorption Spectroscopy ◽  
Aerosol Composition ◽  
Large Variability ◽  
Extinction Coefficients ◽  
Ambient Aerosol ◽  
Wide Range

Abstract. In the field, aerosol in-situ measurements are often performed under dry conditions (relative humidity RH<30–40%). Since ambient aerosol particles experience hygroscopic growth at enhanced RH, also their microphysical and optical properties – especially the aerosol light scattering – are strongly dependent on RH. The knowledge of this RH effect is of crucial importance for climate forcing calculations or for the comparison of remote sensing with in-situ measurements. Here, we will present results from a four-month campaign which took place in summer 2009 in Cabauw, The Netherlands. The aerosol scattering coefficient σsp(λ) was measured dry and at various, predefined RH conditions between 20 and 95% with a humidified nephelometer. The scattering enhancement factor f(RH,λ) is the key parameter to describe the effect of RH on σsp(λ) and is defined as σsp(RH,λ) measured at a certain RH divided by the dry σsp(dry,λ). The measurement of f(RH,λ) together with the dry absorption measurement (assumed not to change with RH) allows the determination of the actual extinction coefficient σep(RH,λ) at ambient RH. In addition, a wide range of other aerosol properties were measured in parallel. The measurements were used to characterize the effects of RH on the aerosol optical properties. A closure study showed the consistency of the aerosol in-situ measurements. Due to the large variability of air mass origin (and thus aerosol composition) a simple parameterization of f(RH,λ) could not be established. If f(RH,λ) needs to be predicted, the chemical composition and size distribution needs to be known. Measurements of four MAX-DOAS (multi-axis differential optical absorption spectroscopy) instruments were used to retrieve vertical profiles of σep(λ). The values of the lowest layer were compared to the in-situ values after conversion of the latter to ambient RH. The comparison showed a good correlation of R2=0.62–0.78, but the extinction coefficients were a factor of 1.5–3.4 larger than the in-situ values. Best agreement is achieved for a few cases characterized by low aerosol optical depths and low planetary boundary layer heights. Differences showed to be dependent on the applied MAX-DOAS retrieval algorithm. The comparison of the in-situ data to a Raman lidar (light detection and ranging) showed a good correlation and higher values measured by the lidar (R2=0.79, slope of 1.81) if the Raman retrieved profile was used to extrapolate the directly measured extinction coefficient to the ground. The comparison improved if only nighttime measurements were used in the comparison (R2=0.93, slope of 1.19).

Protein

1995 ◽  
Author(s):  
Roland Lüthy ◽  
David Eisenberg
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Amino Acid ◽  
Isoelectric Point ◽  
Extinction Coefficient ◽  
Titration Curve ◽  
Side Chains ◽  
Pka Values ◽  
Extinction Coefficients ◽  
Molecular Weights

Given a protein sequence, the amino acid composition can be determined by counting the number of residues of each type. Then a molecular weight can be calculated by summing the molecular weights of the individual amino acid residues, taking into account the loss of one H2O molecule per peptide bond. Table 1 lists the molecular weights of the twenty amino acids and water. This approach assumes that the protein has not been covalently modified. Because of extensive glycosylation of some proteins, this approach can significantly underestimate the actual molecular weight. With the pKa values of Table 1, it is possible to calculate the theoretical charge of a protein at a given pH by summing the charges of the amino acid side chains and of the amino terminus and carboxyl terminus. By performing this calculation over a pH range, one obtains a theoretical titration curve and an isoelectric point (the pH at which the protein hasanetchargeof zero). This method assumes that all normally titratable groups are accessible to water, and that all side chains have the intrinsic pKa values listed in Table 1. This assumption is not completely correct, and consequently, the theoretical isoelectric point may differ from the experimentally determined value. Figure 1 shows the calculated titration curve for pancreatic ribonuclease: the calculated isoelectric point is 8.2, whereas the measured value is 9.6 (Lehninger, 1977). The calculation of extinction coefficients (Gill and von Hippel, 1989) is performed in much the same way as that of the isoelectric point Individual residues are treated as if they are free amino acids, and the overall extinction coefficient is calculated as the sum of the extinction coefficients of the residues. The same basic assumption is made: Residues are assumed to be in typical environments and not to show unusual absorption due to their local environments. In the case of the extinction coefficient, however, this assumption seems to be generally acceptable; calculated extinction coefficients are typically within a few percent of the experimentally determined value, and errors of more than 15% are rare (Gill and von Hippel, 1989).

Extinction coefficient and recombination rate of benzyl radicals. I. Photolysis of sodium phenylacetate

1972 ◽  
Vol 94 (23) ◽  
pp. 7981-7986 ◽  
Author(s):  
Theodore O. Meiggs ◽  
Leonard I. Grossweiner ◽  
Sidney I. Miller
Keyword(s):  
Extinction Coefficient ◽  
Recombination Rate ◽  
Benzyl Radicals ◽  
Sodium Phenylacetate

scholarly journals Seasonal Variations of Volcanic Ash and Aerosol Emissions around Sakurajima Detected by Two Lidars

Atmosphere ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 326
Author(s):  
Atsushi Shimizu ◽  
Masato Iguchi ◽  
Haruhisa Nakamichi
Keyword(s):  
Particle Size ◽  
Extinction Coefficient ◽  
Volcanic Ash ◽  
Surface Wind ◽  
Three Dimensional ◽  
Japan Meteorological Agency ◽  
Extinction Coefficients ◽  
Ash Fall ◽  
Dimensional Distribution ◽  
Aerosol Emissions

Two polarization-sensitive lidars were operated continuously to monitor the three-dimensional distribution of small volcanic ash particles around Sakurajima volcano, Kagoshima, Japan. Here, we estimated monthly averaged extinction coefficients of particles between the lidar equipment and the vent and compared our results with monthly records of volcanic activity reported by the Japan Meteorological Agency, namely the numbers of eruptions and explosions, the density of ash fall, and the number of days on which ash fall was observed at the Kagoshima observatory. Elevated extinction coefficients were observed when the surface wind direction was toward the lidar. Peaks in extinction coefficient did not always coincide with peaks in ash fall density, and these differences likely indicate differences in particle size.

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