Investigation of hydrogen saturated nanodiamonds by electron-positron spectroscopy

Carbon nanostructure materials have been extensively studied and found their application in a wide range of science and engineering fields since the moment of their discovering. Nanodiamonds are likely to share some of the unique properties of macroscopic diamond that are very attractive for a number of applications. The positron annihilation spectroscopy is unique method for characterization of defects and pores of carbon nanostructure materials [1, 2]. The method is based on the interaction of positrons with electrons of a sample [3]. The structure of nanodiamonds and their defects influence the hydrogen sorption capacity. Positronium can be used as a sensor for detecting places with the most efficient capture of hydrogen atoms.

Nanodiamond samples with different density and porosity have been prepared by the hydraulic pressing. The hydrogen concentration of the samples is 1.2 wt% at the temperature of 300 K and the pressure of 0.6 MPa. The porosity of the carbon material before hydrogenation has no considerable impact on the positron lifetime and Doppler broadening. In spite of the fully desorbed hydrogen, the positron annihilation parameters have changed. The nanodiamonds hydrogen saturation leads to the change of the lifetime of trapped positrons and positronium, intensity, S and W-parameters.

References

1. Budziak, J. Dryzek, J. Krawczyk, P.M. Zielinski, Acta Physica Polonica A (2012) 117, 574.
2. Chakrabarti, P.M.G. Nambissan, C.D. Mukherjee, K.K. Bardhan, C. Kim, K.S. Yang, Carbon (2010) 44, 948.
3. Laptev, A. Lider, Y. Bordulev, V. Kudiiarov, G. Garanin, J. Alloys Compd (2015) 645, 193–195.