Transmittance ratio, measurement

In the substrate standard method the absorption effect is determined using the transmittance ratio (T =1. /I ), The determination of the transmittance involves additional measurements, i.e., step scanning over the silver profile, to obtain I. and I , IA is measured for each filter sample and if can be obtained several ways as discussed below, gThese additional measurements can be performed very quickly compared to the more lengthy measurements of the internal standard because the silver peak is quite intense, A step scan of the silver diffraction profile plus background counting time can be accomplished in about two minutes with better than 1% precision,... 

The ratio of the radiant power after and before the transmission of the electromagnetic radiation through the absorbing layer, i. e. transmittance, is measured. Range of operation mid- and far infrared. 

Using the least absorbing (highest transmitting) solution first as the solution in the reference beam, measure the apparent transmittance (transmittance ratio) of the next most concentrated solution and so on. 

Determining Concentration by Turbidimetry In turbidimetry the measured transmittance, T, is the ratio of the transmitted intensity of the source radiation, fy, to the intensity of source radiation transmitted by a blank, Iq. 

The fifth type of tap is unique in that the downstream tap location varies depending of the orifice P ratio. This tap is located at the vena contracta the location where the stream issuing from the orifice attains its minimum cross section. The location of this tap is defined from the upstream face of the orifice as is the D/2 tap. The downstream tap for corner, flange, and pipe taps is measured from the downstream face of the orifice. Vena contracta taps maximize the measured differential pressure. For modem transmitters this is not an important consideration and this type of tap is no longer widely used. 

Direct photography of drops in done with the use of fiber optic probes using either direct or reflected light. StiU or video pictures can be obtained for detailed analysis. The light transmittance method uses three components a light source to provide a uniform collimated beam, a sensitive light detector, and an electronic circuit to measure the amplified output of the detector. The ratio of incident light intensity to transmitted intensity is related to interfacial area per unit volume. 

Define Iq to be the intensity of the light incident upon the sample and I to be the intensity of the beam after it has interacted with the sample. The goal of the basic inftared experiment is to determine the intensity ratio I/Iq as a function of the frequency of the light (w). A plot of this ratio versus the frequency is the infrared spectrum. The inftared spectrum is commonly plotted in one of three formats as transmittance, reflectance, or absorbance. If one is measuring the fraction of light transmitted through the sample, this ratio is defined as... 

Opacity or transparency is important when the amount of light to be transmitted is a consideration. These properties are usually measured as haze and luminous transmittance. As reviewed haze is defined as the percentage of transmitted light through a test specimen that is scattered more than 2.5° from the incident beam. Luminous transmittance is the ratio of transmitted light to incident light. Table 5-7 provides the optical and various other properties of different transparent plastics. 

The simulated FBAC consists of an acrylic main reactor (0.5m-H x 0.5m-W x l.Om-L), an air distributor system, particles feeding system including a feed hopper, a discharging sampler, a bag filter for capture of the elutriated fine particles and, pressure and flow rate measurement systems (Fig. 1). The air distributor system has ten air headers. An individual air header is connected with 5 air nozzles and can regulate the airflow rate. The opening ratio of the distributor is 2.1% and each nozzle has four holes for uniform air supply. To measure the pressure fluctuation at an individual air header, high frequency pressure transmitters were mounted at the approach and the exit headers of the FBAC. 

The comparatively straightforward link between 5-HT and its primary metabolite, 5-HIAA, encouraged many researchers to use changes in the ratio of tissue concentrations of 5-HIAA and 5-HT as an index of the rate of release of 5-HT ex vivo. However, it has been clear for some time that the majority of 5-HT is metabolised in the cytoplasm by MAO before it is released from 5-HT nerve terminals. Consequently, the reliability of the 5-HIAA 5-HT ratio as an index of transmitter release is rather dubious, although it could be used as an acceptable measure of MAO activity. In any case, the development of in vivo microdialysis means that changes in the concentration of extracellular 5-HT can now be monitored directly which, under drug-free conditions, provides a far more reliable indication of any changes in the rate of release of 5-HT. 

In PCL systems care must be taken to ensure that the signal received directly from the transmitter does not compete with and swamp that from the target. Typically this will be the case unless measures are taken to suppress the direct signal occurring in the indirect channel. We can formulate a simple expression for the amount of direct signal suppression required by calculating the ratio of the indirect received sig-... 

Transmittance (T) Ratio of radiant power transmitted by sample to radiant power incident to it Absorbance (A) Logarithm to the base 10 of the reciprocal of the transmittance Absorptivity (a) Ratio of the absorbance to the product of the concentration and the length of the optical path. (If only one cell is used for all the work, the path length will be constant and can be left out of all ealens without introducing an e rror. To simplify the ealen, all measurements were made with the same 0.209mm cell. Hence, all the absorptivities were referred to a 0.209mm [ basis)... 

Band intensities are expressed as either transmittance (T) or absorbance (A). Transmittance is the ratio of the radiant power transmitted by a sample to the radiant power incident on the sample. Absorbance is the base 10 logarithm of the reciprocals of the transmittance A = logi0T. Quantitative measurements in the infrared usually begin with Beer s law and its analogs ... 

The fundamental elements of an ultraviolet-absorption analyzer include (a) a radiation source (b) suitable optical filters (c) a sample cell and (d) an output meter. A transmittance measurement is made by calculating the ratio of the reading of the output with die sample in the cell to die reading widi the cell empty (of ultraviolet-absorbing materials). The concentration can be calculated from the known absorptivity of the substances as previously demonstrated by the equations or it may be determined by comparison with known samples. 

Fig. 6.29. Variation of (a) the total and diffuse transmittance curves (TT and DT), (b) the haze factor measured at A = 600nm (DT/TT at 600nm), as a function of the H2O/DEZ ratio, for 2.5 j,rn-fhick LP-CVD ZnO B films deposited at 155°C, 0.5mbar and with B2H6/DEZ = 0.6...

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