Z. H. Zheng, the first author, neglected to discuss the contents of the above-mentioned paper with his co-authors (K. Okamoto, H. C. Ko, Y. Kawakami, and Sg. Fujita) before publication. He himself assumes the responsibility for this article, but his co-authors request that their names be omitted from the published byline. The new byline should therefore read as:

      ^a)

      Laboratory of Excited State Processes and Changchun Institute of Physics, Chinese Academy of Sciences, Changchun 130021, China.