## Publication Abstracts

### Ho 1966

Ho, W.W.-Y., 1966: The Atmosphere of Venus. Ph.D. thesis. Columbia University.

Pressure-induced absorption in CO_{2} has been studied at a frequency of 9260 Me/sec over a temperature range from 273°K to 500°K and to pressures as high as 95 atm. Mixture CO_{2} and N_{2} have been studied for eight different concentrations of CO_{2} from 240°K to 500°K and to pressures up to 130 atm. Sample mixtures consisting of approximately 10% CO_{2}-90% A and 10% CO_{2}-90% Ne were also studied.

The dielectric loss, ε″, for pure gases was fitted with an expression consisting of a series expansion in the amagat density ρ of the form,

ε″/νi̅ρ = A_{1}ρ + A_{2}ρ^{2} + ...

here ν̅ is the frequency in wave numbers.

For pure CO_{2}, it was found that A_{1} = 2.5(1)×10^{-8}(T/273)^{-3.0(l)},

A_{2}/A_{1} = -1.05(8)×l0^{-2}(T/273)^{-2.3(3)},

where the temperature T is in degrees Kelvin, and for N_{2},

A_{1} = 0.014(2)×10^{-8}(T/273)^{-2.8(3)}.

The coefficient A_{1} is interpreted as the contribution due to transient dipole moments induced by the quadrupole field of the molecules in a binary encounter, and similarly A_{2} is that due to effects of ternary interactions. Terms of higher order could not be determined because of the limit in sensitivity of the_experiment, and A_{2} was only measured for pure CO_{2}.

Calculations of the molecular quadrupole moment from the first coefficient A_{1} of the dielectric loss yielded the results,

Q_{CO2} = 5.8×l0^{-26} esu,

Q_{N2} = 0.9×l0^{-26} esu.

It was found experimentally that the dielectric loss for gas mixtures consisting of CO_{2}, N_{2}, A, and Ne can be expressed in the form, correct to ρ^{2}, by

ε″/ν̅ρ_{T}^{2} = Sum(i-1,N) Sum(j≤1) A_{ij} f_{i} f_{j},

where ρ_{T} is the total density in amagat units, f_{i} is the molar fraction for gas i, A_{ii} is the self-loss coefficients for pure gases, and A_{ij} is the cross term corresponding to binary interactions of two dissimilar molecules.

The self loss of A and Ne are zero to order ρ^{2}, and the cross terms are found to be

A_{CO2-N2} = 0.62(4)(T/273)^{-2.7(2)}×10^{-8},

A_{CO2-A} = 0.42(4)(T/273)^{-2.5(2)}×10^{-8},

A_{CO2-Ne} ≤ 4×10^{-10} at 273 K.

For purpose of calculating the microwave opacity of the Venus atmosphere, the absorption coefficient α for a mixture of CO_{2}, N_{2}, A, and Ne may be approximated by the following expression which is faithful to the laboratory data to within a few percent ever the range of pressures and temperatures relevant to Venus:

α = P_{t}^{2}ν̅^{2}(T/273)^{-5}(15.7 f_{CO2}^{2} + 3.90 f_{CO22}f_{N2} + 2.64 f_{CO22}f_{A} + 0.085 f_{N2}^{2}) ×10^{-8}/cm,

where P_{t} is the total pressures in atmospheres.

Applications of the experimental results to the atmosphere of Venus, under the assumption that the opacity of the atmosphere is mainly due to pressure-induced absorption, show that the frequency dependence of the observed radiofrequency emission from the planet can be well explained by model atmospheres consisting of dilute concentrations of CO_{2}, where the surface pressure is in the range of 100 to 300 terrestrial atmospheres.

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#### BibTeX Citation

@phdthesis{ho07500f, author={Ho, W. W.-Y.}, title={The Atmosphere of Venus}, year={1966}, school={Columbia University}, address={New York}, }

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#### RIS Citation

TY - THES ID - ho07500f AU - Ho, W. W.-Y. PY - 1966 BT - The Atmosphere of Venus PB - Columbia University CY - New York ER -

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