Measurement of the electron-impact transfer rate coefficients between the Kr(1s) states in an afterglow discharge

The rate coefficients for the electron-impact transfer from Kr(1s₅) to Kr(1s₄) and from Kr(1s₃) to Kr(1s₂) are measured in the electron temperature (T _e) range between 0.07 eV and 1 eV. In the afterglow of a capacitive krypton discharge at a fixed pressure of 20 mTorr and a peak rf power ranging from 4 to 128 W, the densities of four krypton 1s states, the electron temperature and the electron density are measured by diode laser absorption, a Langmuir probe and a microwave interferometer, respectively. With these measured quantities, the rate coefficients are obtained from a population model for krypton metastable states. The measured rate coefficients are compared with those derived from the excitation cross sections of Kr metastable states calculated by different R-matrix models. It is found that our results agree best with that from Allan et al [1]. Moreover, we analyze the assumptions made in the population model and discuss their possible impact on the accuracy of the measured rate coefficients, especially for the low T _e (0.1-0.2 eV) range and a higher T _e (0.4-1 eV) range.