resumo
30 keV Cd-111m and 50 keV Hg-199m beams from ISOLDE were used to implant on preformed targets of C-60 with a thickness of 1 mg cm(-2). Endofullerene compounds, viz. Cd-111m@C-60 and Hg-199m@C-60 formed during implantation were separated by filtration through micropore filter paper followed by solvent extraction. Dried samples of the endofullerene compounds were counted for the time differential perturbed angular correlation (TDPAC) measurement using the coincidence of the 151-245 keV cascade of Cd-111m and the 374 158 keV cascade of Hg-199m on a six LaBr3(Ce) detector system coupled with digital electronics. The results for 111mCd@C60 indicate a single static component (27%) and a fast relaxing component (73%), the latter implying that the cadmium atom moves rapidly inside the cage at room temperature. The quadrupole interaction frequency and asymmetry parameter of the cadmium atom occupying the static site in C60 are omega(Q) = 8.21(36) Mrad s(-1) and eta = 0.41(9), respectively. The fast relaxation constant is 0.0031(4) ns(-1). Similarly, mercury atoms also exhibit a single static and a fast component. The static site has a quadrupole frequency omega(Q) = 283.0(12.4) Mrad s-1 and eta = 0 with a fraction of 30%. The fast relaxation constant is 0.045(8) ns(-1) with a fraction of 70%, very similar to that of cadmium.
palavras-chave
NUCLEAR-QUADRUPOLE INTERACTION; ENDOHEDRAL METALLOFULLERENES; METAL ATOMS; DIMETALLOFULLERENES; IMPLANTATION; MOTION
categoria
Chemistry; Physics
autores
Das, SK; Guin, R; Banerjee, D; Johnston, K; Das, P; Butz, T; Amaral, VS; Correia, JG; Barbosa, MB
nossos autores
Vitor Brás Sequeira Amaral
Professor Catedráticoagradecimentos
The authors sincerely thank all the ISOLDE crew members who were engaged in giving ion beams of 111mCd and 199mHg. The authors also thank the ISOLDE group for providing funds to us to carry out the experiment at ISOLDE. Some of us (S.K.D., R.G., D.B.) sincerely thank Dr. K L Ramkumar, Director, Radiochemistry and Isotope Group and Dr. A. Goswami, Head, Radiochemistry Division, BARC for their keen interest in this work. One of us (P.D.) sincerely thank Dr. D.K. Srivastava, Director, VECC for his keen interest in the work.