Gaseous calibration curves

This method may be applied to solid, liquid, or gaseous samples. Considering the fact that the difference in wavenumbers between the Stokes and the anti-Stokes signals is frequently large, the spectral sensitivity of the detector should be taken into account. A calibration curve may be obtained, as proposed by D Orazio and Schrader (1974). A typical example is shown in Fig. 6.8-16 see also Sec. 2.4 and Fig. 2.4-2. 

Of the various methods available for the determination of ozone in gaseous mixtures (4), the spectrophotometric methods, particularly the ultraviolet, appeared to be most suited for the purpose. These methods are all based on the strong absorption maximum for ozone in the ultraviolet at 254 mjm,. Thus, one can determine ozone concentration with a Beckman spectrophotometer by the usual procedure. Several other instruments (I, 3, 6) have been specifically designed to measure ozone concentrations by this photometric method. The meters constructed by the authors also operate on this principle. The total ozone stream, or an aliquot of known proportion, is passed through the meter and the per cent transmittance at 253.7 mju, is read from the dial. The ozone concentration at this temperature and pressure is then either determined from a calibration curve (Figure 1), constructed from titration data (the dial could bo calibrated directly in concentration units), or calculated (3) using Beer s law ... 

In order to study sub-detonation reactions and at the same time to take advantage of the available calibration information, the standardized test is modified as shown in Fig 8 reproduced from NOLTR 64-53 (Ref 59). Although this test retains the standardized donor/gap system, its acceptor is unconfined and much shorter. Chemical reaction is desurveillance of the acceptor. Burning is evidenced by the break-out of gaseous products. The curve for time of break-out (time of shock arrival at free surface to time gas is observed) can be extrapolated to give the critical pressures just to initiate the burning... 

The calibration coefficient is also dependent on other instrumental variables such as furnace atmosphere. David (104) determined X as a function of temperature while varying the composition of the furnace atmosphere (air, N2, or He) and also the pressure (5 x 10 6 Torr to 147 atm). The effect of different gaseous atmospheres on the value of K is shown in Figure 5.40 (104). The difference between the curves can be related to the different thermal conductivities of the gases studied. It was found, as expected, that K was independent of heating rate in the range from 2-40°C/min. 

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