The local structures of Pt thin films grown by molecular beam epitaxy with the thickness range from 3 to 105 nm have been studied by the grazing incidence fluorescence XAFS technique. The results indicate that the local structures of Pt thin films of 30 and 105 nm are similar to that of Pt foil. Four peaks located at 2.61

3.80

4.63

5.43 ? appear in the radial structural function (RSF) of 105 nm Pt thin film

which are corresponding to the first

second

third and fourth Pt-Pt shells

respectively. For the first shell of 30 nm Pt thin film

the coordination number N is 11.9

the bond length R is 2.77 ?

and the Debye-Waller factor σ2 is 0.0055 ?2. With the thickness decreasing from 105 to 3 nm

the magnitude of the first RSF peak decreases obviously for the 3 nm Pt thin film

despite their peak shapes are similar. The N

R and σ2 are 10.1

2.78 ?

0.0077 ?2 and 11.3

2.77 ?

0.0061 ?2 for the Pt thin films of 3 and 10 nm

respectively. Moreover

the RSF peaks in higher shells almost disappear for the 3 and 10 nm Pt thin films. These results show that the medium-range order around Pt atoms is largely destroyed for the Pt thin films. The XAFS results imply that the local structures of 105 nm Pt thin films grown at 350—800 °C are close to that of the Pt crystal.