Measurements Of Branching Fractions For Some Levels In Mo Ⅰ、Mo Ⅱand SnⅠ

Humanity know of the universe is almost entirely from the research in the light ofthe stars. So spectroscopy occupies a very important position in astrophysics. We canget the abundance of various elements in stars from the spectral analysis. And we cananalyse the evolution process of the stars, validate the elements nucleosynthesis theoryand so on. Acurate atomic data such as transition probabilities and oscillator strengthsare needed in the analysis of stellar spectra as well as examining the approximatetheory in atomic physics. The results of lifetime and branching fraction obtained hereare combined together to determine the transition probability and oscillator strength.At present, this is the most reliable and commonly used method.The radiative lifetime is measured by using time-resolved laser-inducedfluorescence technique. And branching fraction is measured by using gratingspectrometry.In this work, we measured branching fractions of five levels of Mo I belonging to4d~5(4P)5p,4d~5(~2D)5p configurations, branching fractions of nine levels of Mo IIbelonging to4d~4(~3H)~5p,4d~4(a~3F)5p,4d~4(~3G)5p configurations, branching fractions ofsix levels of Sn I belonging to8p,16f,18f and some other configurations. Bycombining the upper level lifetimes measured by others, we calculated the transitionprobabilities and oscillator strengths.In a word, the results of the experimental measurement not only enrich the atomicand ionic data in spectral analysis, and on the development of atomic structure theory,the research and application in plasma physics and laser physics also have importantvalues.