P1–20: Specifying the necessary conditions for cloverleaf patterns formation in field emission microscope

The cloverleaf patterns, which were firstly discovered by using field emission microscope in 1950, have been still mysterious and its formation mechanism remained unsolved for 60 years. In this report, it was described that our group successfully specified the necessary conditions in order to observe the cloverleaf pattern. In results, it was cleared that molecule orbital, adsorption state and electron beam induced modulation play the important roles to form cloverleaf patterns.