Field emission and ion microscopy about cloverleaf pattern

In 1950, E. W. Miiller reported firstly the very feature cloverleaf patterns, which were able to be observed in field emission microscope (FEM) by using many kinds of adsorbed organic small molecules on tungsten tip. Since this discovery till now days, many papers have been reported and several theories have been proposed to explain about these phenomena. Also, relatively complicated total electron distribution (TED) spectrums implied that the electron transmitting processes were related with elastic and non-elastic scattering processes. However, even on today spending about 60 years from the first report, the formation mechanism of cloverleaf patterns has not been completely understood and remains still mysterious. We have also studied about cloverleaf patterns mainly by using graphite nano-needle (GRANN), which shows the superior emission property. In previous conference, the key factors for cloverleaf pattern were partly cleared. In this report, field ion microscope (FIM) was adapted to reveal the real images of emission sites. In addiction, in order to specify the necessary and sufficient conditions, FEM investigation by using simple gas molecules including non-carbon was tired.