Au Ion Induced Modification of C 60 Thin Film Samples
- PDF / 1,035,569 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 0 Downloads / 221 Views
NN9.7.1
Au Ion Induced Modification of C60 Thin Film Samples
Navdeep Bajwa1, 3, Alka Ingale2, 4, D.K. Avasthi3, Ravi Kumar3, A.Tripathi3 K. Dharamvir1, V.K.Jindal1∗, Michael Schmitt4, W.Kiefer4 1 Department of Physics, Panjab University, Chandigarh-160014, India 2 Laser Physics Division, Center For Advanced Technology, Indore-452013 India 3 Nuclear Science Center, Aruna Asaf Ali Marg, New Delhi-110067, India 4 Institut fuer Physikalische Chemie, Universitaet Wuerzburg, D-97074 Wuerzburg, Germany The present work reports phase transformations of thin films of C60 irradiated with 100 MeV 197Au8+ ions. This work is in continuation with our earlier work using 58Ni10+ and 16O6+ ions, to study the modification in C60 thin films. The study of C60 thin films using 197Au8+ ions, provides us enough additional data to investigate thoroughly the role of Se in causing phase transformations under different ion fluences. The Raman spectra indicate that swift heavy ion (SHI) irradiation results in several transformations of crystalline C60. At low fluences along with the fragmentation of C60 there is dimer/polymer formation. As fluence increases the dimer/polymer content first rises, optimizes, decreases and finally vanishes at very high fluences. At high fluences, all the C60 molecules as well as the polymer C60 break up, possibly resulting in nano-crystalline graphite embedded in amorphous carbon (a-C). INTRODUCTION The third form of carbon C60 (fullerene) has been a subject of detailed investigation since its discovery in 1985 [1]. These materials have been irradiated by various low and high energy ions to study the modifications taking place in these materials and their resulting applications. Researchers like Kastner et.al. [2] have reported transformation of C60 to amorphous carbon on irradiation by 30 keV K+ ions. Later, a detailed investigation done by Palmetshofer and Kastner [3] using keV ions showed polymerization of C60 at low fluences before it finally transforms to amorphous carbon. The intensity of polymerization was observed to increase at low fluences which reaches a maximum and finally decreases at high fluences. They also showed that amongst H, He, C and Ar (i.e., ions with increasing Se value), maximum of polymerization for H is at the highest fluence ~ 1016 ions/cm2 and is most intense followed by He, C and then Ar. Thus it can be concluded that for low energy ion irradiations (i.e., in keV energy range) the maximum of polymerization is strongly dependent on the Se value of the ion. Researchers like Itoh et. al. [4] have reported fragmentation of C60 induced by impacts of 2 MeV Si++ ions. However, recently Lotha et. al. [5] have reported polymerization of C60 prior to its transformation to a-C. A detailed ∗
Author with whom correspondence be made, [email protected]
NN9.7.2
work is needed to study the trend of the phase transformations taking place in thin films of C60 using SHI’s. The area of investigation using SHI has still remained incomplete. To study the modifications in C60 thin films using SHI, some
Data Loading...
