cyc
= classical absorption coefficient of mixture not in-
cluding relaxation (approximately the same as pure air for dilute solution) atm-sec2/cm aT = the absorption coefficient of the mixture, atm-sec2/cm The detector readout signal would be comprised of the ratio of the difference of the acoustic energy absorbed at each frequency to the acoustic energy absorbed at the frequency below the relaxation frequency of hydrogen: (E, - Eb)/Eb. The absorption coefficients at each frequency are related by the expression: ac,S, = c t c b s b . Substitution of this expression into the signal equation yields:
The exponential term may be expanded into the series function : e-x
=
1 - x, x
0, x = m A S a
Therefore, signal equation can be reduced to : Ea - Eb _-
=
naJ,, ncuAS,
