Scientia Sinica

40 SCIENTIA SINICA Vol, V

Substituting this into (22), we get for the absorption coefficient per wave length 1

(C,—Cy) co wT2

B= 28 CO CC, CP wt (26) Substituting (20) and (21) into (17), we get EGCG: ia een (27) Combining (27) with (26), we get — (C,—C,) Co On WO b=2z VC. C,CO CH C, Co Co w2, tw? : (28) Disregarding intermolecular forces, we obviously have per mole, €, — C, = R, and Cf’ —CHY =R, and (28) becomes simplified to RC® Om ; B= mae (29)

VC(CVER) CP (CHER) om —w

This agrees with the well-known Kneser-Bourgin equation (see equation for tan # in reference [7] and equation (9.4) of reference [6]). Denoting C, by C, C® by C., and C” by C;, we may write this equation in the form given by Fricke!?:

2x RC; On O V_G(C2=R Ga (GEER) lente:

— ; (29a)

where C;=C—C..

Substituting (11) into (27), we get for the thermal relaxation time, ie., the average lifetime of the energy quanta in the excited internal state of the molecule,

_- IGG, oh on V COCO ? (30) or, when the intermolecular forces are disregarded,

1 me CG=ER) (31)

Th =. C(Co+R) >

which is also in agreement with that given by Fricke.