Z. Naturforsch. 69a, 611 – 618
(2014)
doi:10.5560/ZNA.2014-0055
Perturbed Angular Correlation Study of the Static and Dynamic Aspects of Cadmium and Mercury Atoms Inside and Attached to a C60 Fullerene Cage
Satyendra K.
Das1,
Rashmohan
Guin1,
Debasish
Banerjee1,
Karl
Johnston2,
Parnika
Das3,
Tilman
Butz4,
Vitor S.
Amaral5,
Joao G.
Correia6, and
Marcelo B.
Barbosa6
1 Accelerator Chemistry Section (Bhabha Atomic Research Centre), Variable Energy Cyclotron Centre, 1/AF Bidhannagar, Kolkata 700064, India
2 CERN 1211 Geneva 23, Switzerland
3 Variable Energy Cyclotron Centre, Kolkata 700064, India
4 Faculty of Physics and Earth Sciences, University of Leipzig, Linnéstr. 5, 04103 Leipzig, Germany
5 Physics Department and CICECO, University of Aveiro, 3810–193 Aveiro, Portugal
6 ITN, Sacavém, Portugal and ISOLDE-CERN
Received December 4, 2013 / revised July 26, 2014 / published online October 8, 2014
30 keV 111mCd and 50 keV 199mHg beams from ISOLDE were used to implant on preformed targets of C60 with a thickness of 1 mg cm−2. Endofullerene compounds, viz. 111mCd@C60 and 199mHg@C60 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 151–245keV cascade of 111mCd and the 374–158keV cascade of 199mHg 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 ωQ = 8.21(36) Mrad s−1 and η = 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 ωQ = 283.0(12.4) Mrad s−1 and η = 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.
Key words: Endofullerene; Radioactive Ion Beam; TDPAC; Inert Pair Effect; Correlation Time.
PACS numbers: 61.48.+c; 61.80.-x; 76.80.+y