Absorption Of Monochromatic Light Research Articles

Thermoluminescence properties and new insights on the UV-vis absorption features of colorless quartz after γ-ray irradiation.

In this paper, we present the results of research on the thermoluminescence (TL) and optical absorption (OA) properties of colorless natural quartz (including natural quartz samples, sodium ion (Na+) rich samples (by diffusion), and alkali metal (M+) ion poor samples (by sweep)). In detail, the relationship between the TL glow peaks and the emission wavelength was determined. The dynamics parameters (E T, s, τ) have been computed for all TL peaks on the glow curve. The recombination mechanism electron-hole with the participation of the region energy has been determined for all electron traps in the temperature range of 50-430 °C through thermally stimulated conductivity measurement (TSC). Nonlinearity and approaching signal saturation are observed at doses above 22 Gy for the electron trap at 110 °C, above 45 Gy for the electron trap at 238 °C, and 80 Gy for the electron traps at 325 °C and 375 °C. The role of irradiation and heat treatment in the formation of absorption centers as well as the relationship of these centers to electronic traps have been also investigated in detail. The role of M+ ions and hydrogen ions (H+) for the absorption bands in the UV-vis region has been discussed. The results of the combination of the TL measurement and monochromatic light absorption according to temperature show that the TL process occurs concurrently with the reduction of the absorbent center produced in the irradiation process.

A Review UV Method Development and Validation

Ultraviolet spectroscopy is one important and advanced analytical instrument in the Pharmaceutical industry and used for the last 35 years. The method of analysis is based on measuring the absorption of monochromatic light by colorless compounds in the near-ultraviolet path of the spectrum (200-400nm). The pharmaceutical analysis comprises the procedures necessary to determine such compounds' “identity, strength, quality, and purity”. It also includes the analysis of raw materials and intermediates during the manufacturing process of drugs. The fundamental principle of operation of a spectrophotometer covering the UV region consists that light of a definite interval of wavelength passes through a cell with solvent and falls onto the photoelectric cell that transforms the radiant energy into electrical energy measured by a galvanometer. Ultraviolet-visible spectroscopy is used to obtain the absorbance spectra of a compound in solution or as a solid.

A REVIEW ON INSTRUMENTATION AND VALIDATION METHOD OF UV-VISIBLE SPECTROSCOPY AND HPLC FOR THE ANALYSIS OF DRUGS

The purpose of the present analysis was to identify the application of HPLC and UV/Vis spectroscopy. UV-VIS Spectroscopy is the term used to test the various types of solvents and substances in an analysis. In particular, small-scale enterprises typically prefer spectroscopy, as the cost of equipment is lower and maintenance issues are limited. The analysis approach is based on the calculation of the absorption of monochromatic light in the near ultraviolet direction of a spectrum by colourless compounds (200 400nm). The pharmaceutical analysis requires the necessary procedure for the determination of the "identity, intensity, consistency and purity of such compounds. Analysis of raw materials and intermediates during the drug manufacturing process is also included. The dissociation constant is well known to be the most critical parameter in the production and optimization of a new compound for successful development of formulations. Information on the system of simultaneous equation, difference spectrophotometry, high-performance liquid chromatography (HPLC) or fluid visible ultraviolet spectrophotometry was measured. High performance liquid chromatography (HPLC) is an effective analytical method for drug product evaluation. Methods of HPLC should be able to isolate, detect and quantify the different drugs and drug related degradants that can shape, detect and quantify any drugs and drug related impurities that can be added during synthesis. Validation is the process of determining a method's performance features and limitations and defining the factors that which alter these characteristics and to what extent.

Precise Determination of Liquid Layer Thickness with Downward Annular Two-Phase Gas-Very Viscous Liquid Flow

The paper presents the characteristics of the original optoelectronic system for measuring the values of hydrodynamics of two-phase downward gas-very viscous liquid flow. The measurement methods and results of the research on selected values describing gas–oil two-phase flow are presented. The study was conducted in vertical pipes with diameters of 12.5, 16, 22, and 54 mm. The research was conducted with the superficial velocities of air jg = 0–29.9 m/s and oil jl = 0–0.254 m/s, which corresponded to the values of gas stream density gg = (0–37.31) kg/(m2s) and of liquid gl = (0.61–226.87) kg/(m2s), in order to determine the influence of air and oil streams on the character of liquid films. The variations in oil viscosity were applied in the range ηl = (0.055–1.517) Pas. The study results that were obtained with optical probes along with computer image analysis system revealed vast research opportunities in terms of the identification of gas–liquid two-phase downward flow structures that were generated as well as the determination of the thickness of liquid film with various level of interfacial surface area undulation. The designed and constructed proprietary measuring system is also useful for testing the liquid layer by determining the parameters of the resulting waves. It is considered that the apparatus system that is presented in the article is the most effective in examining the properties of liquid layers of oil and other liquids with low electrical conductivity and a significant degree of monochromatic light absorption. In view of noninvasive technique of measuring characteristic values of liquid films being formed, the above measuring system is believed to be very useful for industry in the diagnostics of the apparatus employing such flows.

Thermal analysis on multijunction photovoltaic cell under oblique incident laser irradiation

Laser beam irradiation was modeled to investigate the thermal responses of multijunction photovoltaic cell to the irradiation of oblique incident monochromatic light. First, the monochromatic light absorption in multijunction photovoltaic cell is formulated with accounting for multiple reflections as well as interferences. Then, an iterative algorithm was established to calculate the depositions of incident laser energy in every layer. Finally, the temperature characteristics of the photovoltaic cell are analyzed with finite element method.

Light absorption in solutions of cetyltrimethylammonium and cetylpyridinium bromides

Absorption of monochromatic light in solutions of cetyltrimethylammonium (CTAB) and cetylpyridinium (CPB) bromides has been studied in the wavelength λrange of 190–1000 nm. The investigation has been performed at 30°C and surfactant concentrations ranging from 5 × 10−5 to 3.5 × 10−3 M. Spectra of solutions of LiBr, KBr, and CTAB in the premicellar concentration region have been shown to coincide with each other. They are unimodal, and the heights of their maxima at λmax ≈ 193 nm depend on Br− concentration alone. In contrast to CTAB solutions, the UV spectra of CPB solutions are characterized by the presence of two absorption maxima near λmax1 = 191 nm and λmax2 = 259 nm, as well as a shoulder at 210–218 nm. Their existence is caused by the presence of both Br− anions and CP+ cations in the solutions. The dependences of the integral absorption in the examined wavelength range on CPB concentration exhibit inflections both in the premicellar region and upon the transition to micellar solutions, with these inflections characterizing the critical dimerization and micellization concentrations, respectively. For CTAB, this regularity has only been observed at the critical micellization concentration. The data on the concentration dependence of the light absorption have resulted in the proposal of a method for determining the degree β of counterion binding by micelles of ionic surfactants. The β values calculated for CTAB and CPB are equal to 0.89 ±0 0.1.

Bundling dynamics of single walled carbon nanotubes in aqueous suspensions

A simple optical method based on absorption of monochromatic light to investigate the dynamics of single walled carbon nanotube (SWCNT) suspensions is described. The well dispersed suspensions display a complex behavior, exhibiting peaks due to resonant scattering from SWCNT bundles with increasing diameters as a function of time. The results indicate that the bundling of SWCNTs initiates almost immediately after termination of sonication (after ∼0.1 h) and continues to increase up to a critical time (∼10 h), above which precipitation according to the Stokes relationship occurs. The absorbance behavior can be explained by the depletion of the effective medium as well as the Mie scattering from growth of bundles. A semiquantitative analysis of the experimental data based on the Mie theory of light scattering from cylindrical particles allows the extraction of diameters at the nucleation and growth of SWCNT bundles. The bundling dynamics have been correlated with the electrical properties such as the sheet resistance and transistor characteristics of the SWCNT thin films. Our work is a useful step toward reproducible solution processed electronics because it provides a simple method to monitor the quality of SWCNT suspensions in real time and correlate it to device characteristics.

Reflection and absorption of light by a wide quantum well with two closely spaced excitation levels

The spectra of reflection and absorption of monochromatic light by semiconductor quantum wells whose width is comparable to the wavelength of exciting radiation are calculated. The case of resonance with two closely spaced excited levels is considered. These levels can arise as a result of splitting of the electron-hole pair energy due to the magnetopolaron effect when the quantum well is placed in a strong magnetic field directed perpendicular to the plane of the quantum well. It is demonstrated that, in wide quantum wells, unlike in narrow quantum wells, the reflectance and absorptance of light depend on the quantum-well width. The theory is applicable at any reciprocal ratio of the radiative lifetime to the nonradiative lifetime of electronic excitations.

Leaf architecture and direction of incident light influence mesophyll fluorescence profiles

Light propagation and distribution inside leaves have been recognized as important processes influencing photosynthesis. Monochromatic light absorption across the mesophyll was measured using chlorophyll fluorescence generated from illumination of the cut edge (epi-illumination), as well as the adaxial or abaxial surfaces of the leaf. Species were selected that had basic leaf types: laminar leaf with adaxial palisade layer (Rhododendron catawbiense), needle with palisade (Abies fraseri), and needle without palisade (Picea rubens). Fluorescence was more evenly distributed across the mesophyll for adaxially illuminated leaves with a palisade cell layer, as well as for the needles (cylindrical) without palisade, when compared to fluorescence generated by abaxial illumination. Moreover, fluorescence from green light illumination remained high across the mesophyll of adaxially illuminated R. catawbiense, indicating a possible influence of mesophyll structure on internal light distribution beyond that of chlorophyll levels. These data support the idea that light propagation within the mesophyll is associated with asymmetric mesophyll structure, in particular the presence of palisade cell layers. In addition, we propose that the evolution of a more cylindrical leaf form, such as found in conifer species, may be a structural solution to excessive sunlight that replaces the highly differentiated mesophyll found in most laminar-leaved species.

Light absorption by a two-dimensional quantum dot superlattice

The monochromatic light absorption in an ideal two-dimensional quantum dot superlattice (QDSL) is considered theoretically. Calculations of the absorption coefficient are done in both the absence and presence of a homogeneous DC electric field with rational and irrational orientations. The explicit dependencies of the absorption coefficient on the frequency of the light, the QDSL parameters and the strength of the electric field are found. Some numerical results for GaAs — Ga 0.7 Al 0.3 As QDSL are obtained.

Collisional shift and broadening of iodine spectral lines in air near 543 nm

The collisional processes that influence the absorption of monochromatic light by iodine in air have been investigated. Measurements were made in both a static cell and an underexpanded jet flow over the range of properties encountered in typical compressible-flow aerodynamic applications. Experimentally measured values of the collisional shift and broadening coefficients were 0.058 ± 0.004 and 0.53 ± 0.010 GHz K 0.7/torr, respectively. The measured shift value showed reasonable agreement with theoretical calculations based on Lindholm-Foley collisional theory for a simple dispersive potential. The measured collisional broadening showed less favorable agreement with the calculated value.

Hemoscan™: A Dialysis Machine-Integrated Blood Volume Monitor

We describe an opto-electronic device capable of measuring the hemoglobin concentration (Hgb) non-invasively and continuously, hence the percentage changes in blood volume (BV) during dialysis treatment by means of the optical absorption of monochromatic light by the blood in the arterial line. This method has been validated during several in vitro and in vivo tests, during which the system has shown a low sensitivity to all the common intra-dialytic interference factors, such as oxygen saturation (max. err. = 1.6%), blood flow (max. err. = 1.8%), osmotic pressure (max. err. = 0.7%) and hydraulic pressure (max. err. = 0.6%), a high precision (std. err. < 0.1 g/dl) and a good accordance (Hgb mean err. = 0.1 g/dl; std. err. = 0.38 g/dl; BV mean err. = 0.1%; std. err. = 1.6%) with the corresponding values derived from standard laboratory tests.

Modelling of light absorption in photoreactors Part I. General formulation based on the laws of photometry

Modelling of monochromatic light absorption in photoreactors is presented using basic concepts of photometry. It is shown that confusion in the definition of “intensity” may be avoided if one starts with the fundamental concept of luminance. The Beer—Lambert law is reformulated allowing unambiguous determination of the radiation field inside the reactor, including the limiting cases of diffuse and unidirectional radiation. The absorption efficiency is defined and calculated for simple reactor geometries. It is shown to depend only on the available specific photochemical power and on an optical thickness proportional in most cases to a characteristic dimension of the reactor.

Modelling of light absorption in photoreactors Part I. General formulation based on the laws of photometry

Modelling of monochromatic light absorption in photoreactors is presented using basic concepts of photometry. It is shown that confusion in the definition of “intensity” may be avoided if one starts with the fundamental concept of luminance. The Beer—Lambert law is reformulated allowing unambiguous determination of the radiation field inside the reactor, including the limiting cases of diffuse and unidirectional radiation. The absorption efficiency is defined and calculated for simple reactor geometries. It is shown to depend only on the available specific photochemical power and on an optical thickness proportional in most cases to a characteristic dimension of the reactor.

Cytochemical and Radioautographic Identification of Cells Induced to Synthesize Hemoglobin

Abstract In order to facilitate the identification of bone marrow cells in which hemoglobin synthesis is initiated, erythropoiesis was first suppressed in guinea pigs through the induction of posthypoxic polycythemia, and then it was restimulated by bleeding and reexposure to hypoxia. Hemoglobin synthesis was detected with 55Fe incorporation on radioautographs, and its presence was demonstrated in the light microscope with the benzidine reaction and absorption of monochromatic light at λ 4046 Å. In the electron microscope, hemoglobin was detected in the cytoplasm by a general increase in electron density after treating the tissue with diaminobenzidine (DAB) and OsO4. Densitometric measurements were carried out on electronmicroscopic negatives, using reticular cell cytoplasm as a base line. In normal marrow, proerythroblasts were the earliest cells in which hemoglobin could be detected, but during the early phase of erythropoietic stimulation, hemoglobin was demonstrated in transitional cells with all the methods employed. Without the specific demonstration of hemoglobin, these cells could not be recognized morphologically as erythroblasts nor could they be distinguished from the precursors of bone marrow small lymphocytes. Transitional cells were numerous in the marrow at the time of stimulation, and 40 hr later a small number of them were labeled with 55Fe and synthesized hemoglobin in detectable amounts. Proerythroblasts were absent at the time of the stimulus, and when they reappeared the majority were benzidine or DAB positive and had incorporated 55Fe. The findings suggest that progenitor cells of erythroblasts are among the basophilic members of the transitional cell population, and erythropoietic stimulation induces hemoglobin synthesis in them. The relationship of these cells to the progenitors of other hemopoietic cells, as well as to the pluripotent stem cell, is discussed.

A gas-hemoglobin diffusion photometer.

A double-beam photometer is described which employs a single photocell and motor-driven shutter synchronized with alternately energized screens in a gated amplifier. The equipment is used for indicating and recording monochromatic light absorption changes by a thin layer of hemoglobin-containing media exposed to diffusion of various gases.

Monochromatic light absorption by chicken erythrocytes. A correction

Monochromatic light absorption by chicken erythrocytes. A correction

Monochromatic light absorption by normal chicken erythrocytes

Monochromatic light absorption by normal chicken erythrocytes

Electronic States and Band-Spectrum Structure in Diatomic Molecules II. Spectra Involving Terms Essentially of the FormB(j2−σ2)

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