Equivalent pathlength

Dispersive IR spectrometers can be either single-beam or double-beam usually they are double-beam instruments. The use of a double-beam instrument significantly reduces the problem of possible interference from carbon dioxide and water vapor in the atmosphere during analysis. The absorption due to a solvent may also be nearly cancelled by placing an equivalent pathlength solvent cell in the reference beam. 

Sensitivity The sensitivity of a molecular absorption analysis is equivalent to the slope of a Beer s-law calibration curve and is determined by the product of the analyte s absorptivity and the pathlength of the sample cell. Sensitivity is improved by selecting a wavelength when absorbance is at a maximum or by increasing the pathlength. 

For Qa < Qo, the equivalent absorption pathlength is given by QaX/2n where X is the wavelength Qo values of 40 000 in temperature-controlled microwave absorption studies at frequencies between 2 and 5 cm-1 have been known (Dagg 1985). 

The experimental and data reduction procedures are essentially the same as for the static cell experiments. The gas temperature is obtained using a fine wire, radiation-corrected thermocouple. The cold mixing layer at each flame boundary is accounted for by using an effective pathlength (8.0 - 8.2 cm, depending on the fuel-air equivalence ratio) which differs slightly from the actual burner length of 8.6 cm. Fuel-air equivalence ratios of... 

Fig. 7.18 MCD spectrum of [Co2(CH3L4)(CH3COO)2]+ in ethanol at 1.5 K and 7.0 T (pathlength 0.62 cm, 8 mM) in the presence of 25 equivalents DPP. On the right magnetization plot from VTVH analysis of the band at 478 nm...

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