23 citations · 175 across the 31 of their papers we have counts for
31 papers
Space-Filling Fractal Description of Ion-induced Local Thermal Spikes in Molecular Solid of ZnO
Shoaib Ahmad, Muhammad Yousuf
Anions of the molecules ZnO, O2 and atomic Zn and O constitute mass spectra of the species sputtered from pellets of molecular solid of ZnO under Cs+ irradiation. Their normalized…
Regenerative Soot-IX: C3 as the dominant, stable carbon cluster in high pressure sooting discharges
Sohail Ahmad Janjua, M. Ahmad, S. D. Khan +3
Results are presented that have been obtained while operating the graphite hollow cathode duoplasmatron ion source in dual mode under constant discharge current. This dual mode ope…
Thermal spikes induced sublimation of carbon nanotubes
Sumera Javeed, Shoaib Ahmad
We report and provide justification for the consistently observed four experimental facts of the mass spectrometric data of carbon cluster emission from the low-energy Cs irradiate…
Dynamics of fragmentation and multiple vacancy generation in irradiated single-walled carbon nanotubes
Sumera Javeed, Sumaira Zeeshan, Shoaib Ahmad
The results from mass spectrometry of clusters sputtered from Cs+ irradiated single-walled carbon nano-tubes (SWCNTs) as a function of energy and dose identify the nature of the re…
Amorphous carbon films in direct current magnetron sputtering from regenerative sooting discharge
Sumera Javeed, Sumera Yamin, Sohail Ahmad Janjua +6
We present results of carbon coatings on metal substrates in cylindrical hollow cathode (CHC) direct current magnetron sputtering. This is a new technique of making amorphous carbo…
Formation and transformation of low density, onion-like carbon cages
Shoaib Ahmad, Uzair Ahmed, Farrukh E. Mubarik +1
A novel growth technique for low density, non-icosahedral carbon onion-like structures on Cu surface is described. The technique differs with the formation of carbon onions inside…
Formation of carbon nano and micro structures on C1+ irradiated copper surfaces
Shoaib Ahmad
A series of experiments has identified mechanisms of carbon nano- and micro-structure formation at room temperature, without catalyst and in the environment of immiscible metallic…
Transition from the C3-dominated discharge to the sooting plasma
Shoaib Ahmad, Bashir Ahmad, Tasneem Riffat
Mass spectrometry and photoemission spectroscopy of a graphite hollow cathode source identify the parameters of the transition from the C(3) dominated discharge to the sooting plas…
Cs+ sputtered clusters from multi-walled carbon nanotubes and graphite
Shoaib Ahmad, Sumera Javeed, Sumaira Zeeshan +6
Experiments with multiwalled carbon nanotubes and graphite as targets in a source of negative ions with cesium sputtering have shown that nanotubes with nanometer radii and microme…
Irradiation induced vacancy creation in single walled carbon nanotubes
Sumera Javeed, Sumaira Zeeshan, Shoaib Ahmad
Single walled carbon nanotubes of 2 nm diameter and 3 to 13 micro meter length were compressed in Cu bullets and irradiated with positive ions of Cs with energies from 0.2 to 2.0 k…
Regenerative Soot-VIII: Sputtering and formation of C1 and C2
Shoaib Ahmad, A. Qayyum, M. N. Akhtar +1
Photoemission spectroscopy of the regenerative soot in neon's glow discharge plasma reveals the contributions from the sputtered atomic and molecular carbon species. We present the…
Carbon cluster diagnostics-I: Direct Recoil Spectroscopy (DRS) of Ar+ and Kr+ bombarded graphite
Shoaib Ahmad, M. N. Akhtar, A. Qayyum +3
Measurements of the energy spectra of multiply charged positive and negative carbon ions recoiling from graphite surface under 100 and 150 keV argon and krypton ion bombardment are…
Carbon cluster diagnostics-III: Direct Recoil Spectroscopy (DRS) versus ExB Velocity Analysis
Shoaib Ahmad, S. A. Janjua, M. Ahmad +3
A comparative study is being reported on the identification of heavy carbon clusters using two different techniques namely the Direct Recoil Spectroscopy (DRS) and velocity spectro…
Regenerative Soot: A cusp field, graphite hollow cathode, carbon cluster ion source
Shoaib Ahmad, Tasneem Riffat
An all carbon hollow cathode ion source with a specially designed cusp magnetic field Bz as a function of radius and theta is described. Velocity spectra from this source has shown…
Regenerative Soot-VII: Population inversion of He I and Ne I in regenerative sooting discharges
Sajid Hussain, A Aleem, Rahila Khalid +4
The mechanisms for population inversion among the excited states of He I and Ne I in regenerative sooting discharges have been investigated as a function of the geometry and the ph…
Regenerative Soot-VI: The excited states of neutral and ionized carbon in regenerative sooting discharges
M Uzair, Sajid Hussain, S A Janjua +1
We report the mechanisms of production and the state of excitation of the neutral and singly charged monatomic carbon in the regenerative soot as a function of the discharge parame…
Regenerative Soot-V: Spectroscopy of the regenerative sooting discharges
Shoaib Ahmad
The mechanisms and processes of the formation of the regenerative soot in a graphite hollow cathode discharge that produces and emits carbon clusters are presented. Mass spectromet…
Regenerative Soot-IV: The state of the carbon vapour in the regenerative sooting discharge
Shoaib Ahmad
Formation of the regenerative soot is the process of recycling and introduction of the cathode deposited carbon clusters into the discharge. The agglomerates of carbon clusters on…
Regenerative Soot-III: Role of the kinetic and potential sputtering in the regeneration of the soot
Shoaib Ahmad, M. N. Akhtar
We have used the photoemission spectroscopy of the graphite hollow cathode sooting discharge to identify the roles played by the kinetic and potential sputtering, respectively. Our…
Regenerative Soot-II: Emission of carbon clusters from sooting plasma
Shoaib Ahmad
A hollow cathode source with a specially designed cusp magnetic field B whose z component is a function of radius and the azimuth angle, provides clustering environment to the sput…
Regenerative Soot-I: Carbon cluster formation in regenerative sooting plasmas
Shoaib Ahmad
Laboratory formation of large carbon clusters with m C atoms where m could be up to few thousand, in carbonaceous plasma, has been studied by using an especially designed ion sourc…
Evolution of clusters in energetic heavy ion bombarded amorphous graphite-II: formation and fragmentation phenomena
A. Qayyum, B. Ahmad, M. N. Akhtar +1
A study has been conducted into the mechanisms of evolution of clusters and their subsequent fragmentation under energetic heavy ion bombardment of amorphous graphite. The evolving…
Evolution of clusters in energetic heavy ion bombarded amorphous graphite-III: Energy spectra of charged clusters recoiling from Xe+ irradiations
Bashir Ahmad, Maqsood Ahmad, Shoaib Ahmad
We report on a novel technique of heavy ion induced surface modification and clustering mechanisms in amorphous graphite using Direct Recoil Spectrometry. The charged clusters eman…
Evolution of clusters in energetic heavy ion bombarded amorphous graphite-III: Photo-emission and velocity analysis of sputtered carbon clusters
A. Qayyum, M. N. Akhtar, T. Riffat +1
Diagnostics of the carbon atoms, ions, and clusters sputtered from a graphite surface under 10 keV Xe ion bombardments reveals the presence of neutral carbon clusters and positivel…