Absorption coefficient and absolute photoionization yield of xenon gas have been measured by photoelectric methods with 0·2Åbandwidth in the 860–1022Åregion. Ionization yields were obtained with a platinum detector calibrated against a calibrated thermocouple. A yield value of unity was obtained throughout this region which includes preionized Rydberg lines. The absorption coefficient at most wavelengths fell between the spread of previous values.

The chapter is confined to only a part of the upper atmosphere research— namely, the study of absorption processes due to solar radiation of wavelengths from about 2900 Å to 1 Å. This chapter attempts to cover the decade from 1946 to the beginning of the International Geophysical Year, or from the first rocket experiments to the first artificial satellite. The chapter summarizes several types of absorption processes important in the study of the upper atmosphere. Some definitions and equation of state of gases in the upper atmosphere are given. Some of the data on atmospheric structure are tabulated and discussed in order to set up an atmospheric model that will be used for subsequent discussions of atmospheric absorption and photochemistry. The study of atmospheric composition and the study of absorption of solar radiation are directly related and usually proceed together. It is possible to determine atmospheric composition from absorption measurements, and reciprocally, data on composition assist calculations of absorption processes. In order to carry out quantitative calculations of atmospheric photochemical processes, it is necessary to have reliable data on absolute spectral intensities of solar ultraviolet radiation including soft x-rays. The chapter presents the absorption cross-sections of atmospheric gases. Several theories on atmospheric photochemistry are described in this chapter.

This report summarizes the measurements of molecular ionization potential by a photoionization method utilizing a 1 m vacuum monochromator in the photon energy range from7–15 eV. The adiabatic ionization potentials of about three hundred molecules determined by the present method are assembled in thirteen tables, which include estimates of experimental uncertainties. In nearly all cases (about forty) where comparisons can be made, the present results agree closely with the spectroscopic values. The identity of the most loosely bound electrons, the effect of alkyl substitution, and the relationship between ionization continua and absorption bands are suggested for some of the molecules.