H • PHYSICAL BASIS OF THERMAL RADIATION 



this question we may note that theoretical studies on diatomic gases 

 [11,1^,13,14,15,16,18] and basic spectroscopic studies for a number of 

 these same gases [£3] have been carried to the point where useful abso- 

 lute calculations and extrapolations are feasible. For polyatomic gases, 

 on the other hand, high temperature calculations are possible in principle 

 but not yet feasible in practice because the required basic spectroscopic 

 constants are not available [17]. For this reason, and because of the com- 

 plexity of theoretical calculations for polyatomic gases and gas mixtures, 

 the most fruitful approach at the present time to the problem of high 

 temperature emissivity estimates must remain an empirical one. It ap- 

 pears very likely that the required basic data for radiant heat transfer 

 calculations in combustion chambers can be obtained by the judicious use 

 of spectroscopic studies on shock tube experiments. Details concerning 

 emissivity calculations for such substances as CO, NO, H2O, heated air, 

 etc. are given elsewhere [24]. 



H,6. Cited References. 



1. Planck, M. The Theory of Heat Radiation. Transl. by M. Masius. P. Blakiston's 

 Son and Co., Philadelphia, 1914. 



2. Page, L. Introduction to Theoretical Physics. Van Nostrand, 1935. 



3. Mayer, J. E., and Mayer, M. G. Statistical Mechanics. Wiley, 1940. 



4. Planck Radiation Functions and Electronic Functions. Federal Works Agency, 

 WPA, Natl. Bur. Standards, 1941. 



5. Forsythe, W. E. Measurements of Radiant Energy. McGraw-BQll, 1937. 



6. Einstein, A. On the quantum theory of radiation. Physik. Z. 18, 121 (1917). 



7. Margenau, H., and Watson, W. W. Pressure effects on spectral lines. Revs. Mod. 

 Phys. 8, 22 (1936). 



8. Van Vleck, J. H., and Weisskopf, V. F. On the shape of collision-broadened 

 Imes. Revs. Mod. Phys. 17, 227 (1945). 



9. Lindholm, E. Dissertation, Uppsala, 1942. 



10. Anderson, P. W. Pressure broadening in the microwave and infrared regions. 

 Phys. Rev. 76, 647 (1949). 



11. Penner, S. S. The emission of radiation from diatomic gases. I. Approximate 

 calculations. Calif. Inst. Technol. Jet Propul. Lab. Progress Rept. 9-37, May 1949. 



12. Penner, S. S. Infrared emissivity of diatomic gases. In Natl. Bur. Standards 

 Circ. 523 (Energy transfer in hot gases), 1954. 



13. Penner, S. S. The emission of radiation from diatomic gases. I. Approximate 

 calculations. J. Appl. Phys. 21, 685 (1950). 



14. Penner, S. S., and Weber, D. Emission of radiation from diatomic gases. II. 

 Experimental determination of effective average absorption coefficients of CO. 

 /. Appl. Phys. 22, 1164 (1951). 



15. Penner, S. S., Ostrander, M. H., and Tsien, H. S. The emission of radiation from 

 diatomic gases. III. Numerical emissivity calculations for carbon monoxide for 

 low optical densities at 300°K and atmospheric pressure. /. Appl. Phys. 23, 256 

 (1952). 



16. Penner, S. S. The emission of radiation from diatomic gases. IV. Emissivity 

 calculations for CO and HCL for nonoverlapping rotational lines as a function of 

 temperature and optical density. J. Appl. Phys. 23, 825 (1952). 



17. Penner, S. S. Approximate emissivity calculations for polyatomic molecules. I. 

 CO2. /. Appl. Phys. 25, 660 (1954). 



18. Penner, S. S. Emissivity calculations for diatomic gases. J. Appl. Mech. 18, 53 

 (1951). 



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