Photoionisationsuntersuchungen an Atomstrahlen

Abstract

The crossed beam technique is for the first time used in a mass spectrometric investigation of photoionization products. The photoionization threshold of atomic hydrogen is 911 Å and its photoionization cross section is exactly calculable. This allows the amount of ionization to be calculated, if the intensity of the radiation and the particle density are known. On the other hand, an unknown photon flux can be determined from the measured proton current. With the new technique the absolute photoelectric yield and/or the photoionization cross section of gases can be measured.The experimental device consists essentially of a UV monochromator, a hydrogen atomic beam, and a mass spectrometer. By the atomic beam technique it is also possible to measure the photoionization cross section of unstable particles such as atomic oxygen and atomic nitrogen.

Photoabsorption cross section of O, S, Se, and Te

“…Our motivation for this study is threefold: (1) we obtain theoretical cross sections for Se and Te and more accurate cross sections for 0 and S and use these theoretical spectra to classify experimental resonances. (2) We demonstrate that some aspects of complex spectra originate from simple considerations. (3) We explore the types of basis functions that are needed for accurate wave functions and thus what physical efFects are important for the description of the dynamics.…”

Absorption cross-sections of atmospheric gases for use in aeronomy

“…Until quite recently there were no experimental values, but measurements using two independent techniques have now been published. One technique uses discharged oxygen, which requires correction for metastable molecules (37), and the other uses a beam technique requiring calibration against hydrogen atom (38). They are in only fair agreement with each other, but they generally bracket the theoretical curve.…”