China
Africa
Explore chapters and articles related to this topic
Synthesis of Nanomaterials for Drug Delivery
Published in Vineet Kumar, Praveen Guleria, Nandita Dasgupta, Shivendu Ranjan, Functionalized Nanomaterials II, 2021
Hemant K. S. Yadav, Shahnaz Usman, Karyman Ahmed Fawzy Ghanem, Rayisa Beevi
As an electron beam enters a solid material or polymeric film, it undergoes elastic scattering, leading to loss in energy. The electron scattering occurs either by elastic collisions or inelastic collisions. Energy is lost only during inelastic collisions, whereas elastic collisions only result in a direction change. Due to the scattering, the electrons spread out and penetrate into the solid. This will result in transversal or lateral flux which is normal for the incident beam direction, causing an exposure of resist at points remote from the point of electron incidence, leading to development of resist images wider than expected. The factors determining the magnitude with which electron scattering will take place are the atomic number, density of the substrate and resist, and also the velocity of electrons.[18]
Nuclear Reactions in a Laser-Driven Plasma Environment
Published in Paul R. Bolton, Katia Parodi, Jörg Schreiber, Applications of Laser-Driven Particle Acceleration, 2018
David Denis-Petit, Ken W.D. Ledingham, Paul McKenna, David Mascali, Salvatore Tudisco, Klaus M. Spohr, Medhi Tarisien
A partial level scheme of the 84Rb nucleus is shown in Figure 22.4. The Jπ = 6−, T1/2 = 20.26(3) minute, isomeric state of the unstable 84Rb nucleus lies at an excitation energy of 463.618(3) keV, which is 3.498(6) keV lower than a Jπ = 5−, T1/2 = 9 ns state [Denis-Petit et al. 2014, Denis-Petit et al. 2017]. In a plasma of T = 400 eV (LTE), four different excitation processes [Harston 1999] can be involved in the excitation of the 6– state to the 5– one via an M1 transition, thus reducing the apparent lifetime of the 6- state. These processes are illustrated in Figure 22.5. The photo-excitation process is a resonant process, where a photon from the plasma directly transfers its energy to the nucleus. The inelastic electron scattering is a process, where an energetic free electron from the hot plasma transfers part or all its kinetic energy to the nucleus. NEEC occurs, when a free electron from the plasma is captured by the ion to fill a vacancy within an atomic orbital. The energy released in the process is transferred to the nucleus via a virtual photon. Both the atomic capture and the nuclear excitation take place within the same atom. Finally, NEET [Kishimoto 2000] occurs when a vacancy in a lower-lying orbital of the atom is filled by an electron from a higher level. In this process, the nucleus can also be excited by the energy released in the atomic transition. The NEET process requires both the electronic and nuclear transitions to carry the same amounts of energy and angular momentum; it is a resonant process.
Comparison of Rutherford’s atomic model with the Standard Model of particle physics and other models
Published in Journal of the Royal Society of New Zealand, 2021
Electron scattering, as used in electron microscopy, is the classic technique for resolving small structures. Such studies confirmed the geometry shown in Figure 2 for the atomic nucleus (Hahn et al. 1956). Subsequent studies of the proton were conducted at higher energies at the Stanford Linear Accelerator Centre (SLAC), and at the Hadron Electron Ring Accelerator (HERA) in Hamburg, but, as noted earlier, the analyses of these studies appear ambiguous.