/matlab/getq.m

 1function k_q = getq(tint,wmr)
 2% getq.m   Get quenching rate as function of internal temperature
 3%          and water mixing ratio supplied in wmr (mole fraction).
 4% getq takes as input the internal temperature 'tint' and returns
 5% the OH fluorescence quenching rate from an 80/20 mixture of N2
 6% and O2.  The coefficients a, b, c were derived from data supplied 
 7% by Heard (Faraday Trans., V93, 1997 for O2 and N2; private comm.
 8% for H2O.)
 9%
10% quenching cross-sections were approximated linearly, of the form
11%	sigma = -mT + n		T in Kelvins
12%
13% k_q(T) = sigma(T) * <v>
14%
15% <v> is the average thermal collision velocity [8RT/(pi*mu)]^1/2,
16% where mu is the reduced mass of the collision.
17%
18% the individual quenching rates have the form
19% 	k = aT^(1/2) - bT^(3/2) + c
20% revised by I. Faloona (12/97)
21% H2O coefficients revised by MM (1/02) according to [Bailey et al., Chem. Phys. Lett., 1999]
22
23kB = 1.381e-19;
24
25% N2
26
27an2 = -1.668e-11;
28bn2 = -1.731e-14;
29cn2 = 2.313e-10;
30
31% O2
32
33ao2 = 1.008e-11;
34bo2 = 1.655e-14;
35co2 = 5.129e-11;
36
37% H20
38
39ah2o = -4.017e-10;
40bh2o = -4.4686e-13;
41ch2o = 5.3137e-09;		
42
43% calculate quenching rate constants
44
45kn2 = an2*tint.^(0.5) - bn2*tint.^(1.5) + cn2;
46ko2 = ao2*tint.^(0.5) - bo2*tint.^(1.5) + co2;
47kh2o = ah2o*tint.^(0.5) - bh2o*tint.^(1.5) + ch2o;
48
49
50k_q = ((1-wmr).* (0.791*kn2 + 0.209*ko2) + wmr.*kh2o)./(kB*tint);