Abstract: At the present time,the phenomena of many particles diffraction have been studied in many experiments,and these experiments have been explained by some theoretical works.We study the double-slit diffraction by a quantum mechanical approach.Starting from the Schredinger equation and using Kirchhoff＇s law,we obtain the diffraction wave functions for the double-slit.We find that when the effects of decoherece is considered in the C60 double-slit diffraction,the calculation results are in accordance with experimental data.

Key words: matter-wave, diffraction, quantum theory, decoherence