Biennial Report 2005-2007 - Saha Institute of Nuclear Physics

168 Biennial Report 2005-07initial crystalline structure by the ion bombardment takes place along particular crystallographicdirections.TK Chini, S Hazra, MK Sanyal, J Grenzer†, U Pietsch†SP5.1.4.7 Sputtering and desorption from SiO 2 surfaces bombarded by highly chargedXe q+ (q = 21,36) ions at an energy of 3 MeV/uRecently, the interaction of swift heavy ions with insulating surfaces has attracted researches in thefield of ion-solid interaction phenomena. At high velocities, the electronic energy loss and excitationare dominant, but on the other hand atomic displacements due to electronic energy-transfersare less probable as compared to nuclear energy-loss events. Following the primary interaction aconversion of these excitations into atomic motion and materials modifications may result. Thebehaviour of thin insulating oxide layers (e.g., BeO) under irradiation by highly charged swift heavyions has revealed interesting results pointing to more than a single sputtering mechanism. In thisstudy, we report on the results of an experiment to investigate the secondary-particle emission froman oxidized Si(111) surface under bombardment with highly charged 129 Xe q+ ions at energies of 3MeV/u. The experiment was performed at one of the beam lines of the Heavy Ion Cyclotron of theHahn-Meitner-Institut Berlin, using a UHV chamber that is equipped with a number of sources anddetectors as analytical tools for in-situ measurements. This particular experiment was aimed atusing a quadrupole mass-spectrometer (Hiden HAL IV EQS System) to analyse the mass spectraand energy distributions of secondary particles emitted from the bombarded sample. Prior to theactual experiment the mass spectrometer was optimized and calibrated so that mass and energyspectra of sputtered and desorbed species could be obtained in various modes of operation. A dataacquisition system was also developed for in-situ measurements.The oxydised Si sample convertedinto SiO 2 on its surface was bombarded by highly charged Xe-ions. The energy distributions ofpositive and negative species sputtered/desorbed from the insulating surface are compared withthose obtained from sputtered particles from the same SiO 2 surface bombarded by 2.2 keV and4.5 keV Ar + ions. Moreover, the projectile charge-states of Xeq+ where increased from q = 21 to36 exhibiting an increase in emission intensities for the masses 1, 16, 32 (hydrogen and oxygen),whereas mass 28 (silicon) is unaffected by this rise of incident charge states.SR Bhattacharyya, G Schiwietz†SP5.1.5 Developmental Activities5.1.5.1 Development of beam line for INDUS II synchrotron at RRCATWe are developing a beam line for the upcoming synchrotron at RRCAT, Indore, since 2001. Thefacility will be used for different kinds of surface scattering measurements from solid as well asliquid surface. The available energy range for the experiments will be 5-20 KeV. We have gonethrough the different stages of the project such as, optical designing of the beam line, procurement