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Chamaeleon
Chamaeleon, a small and inconspicuous constellation in the southern celestial hemisphere, represents the chameleon, a creature known for its ability to change color and blend into its surroundings. Despite its modest size, Chamaeleon holds significance in astronomy for its proximity to the southern celestial pole and its role in studying star formation and stellar evolution.
  • 197
  • 08 Mar 2024
Biography
Chandrasekhara Venkata Raman
Chandrasekhara Venkata Raman, born on November 7, 1888, and passed away on November 21, 1970, was a distinguished Indian physicist renowned for his contributions to the study of light scattering. Alongside his student K. S. Krishnan, he developed a spectrograph and made a groundbreaking discovery – the modification of light scattering when it passes through a transparent material. This phenome
  • 401
  • 17 Feb 2024
Topic Review
Channelling
Channelling is the process that constrains the path of a charged particle in a crystalline solid. Many physical phenomena can occur when a charged particle is incident upon a solid target, e.g., elastic scattering, inelastic energy-loss processes, secondary-electron emission, electromagnetic radiation, nuclear reactions, etc. All of these processes have cross sections which depend on the impact parameters involved in collisions with individual target atoms. When the target material is homogeneous and isotropic, the impact-parameter distribution is independent of the orientation of the momentum of the particle and interaction processes are also orientation-independent. When the target material is monocrystalline, the yields of physical processes are very strongly dependent on the orientation of the momentum of the particle relative to the crystalline axes or planes. Or in other words, the stopping power of the particle is much lower in certain directions than others. This effect is commonly called the "channelling" effect. It is related to other orientation-dependent effects, such as particle diffraction. These relationships will be discussed in detail later.
  • 444
  • 29 Nov 2022
Topic Review
Characterization of MXene's Terminations
MXene, 2D transition metal carbides, nitrides, and carbonitrides with a unique 2D structure, inspired a series of function applications related to energy storage and conversion, biometrics and sensing, lighting, purification, and separation. Its surface terminations are confined by the adjacent MXene layers, and form the 2D planar space with symmetrical surfaces, which is similar to a 2D nanoreactor that can be utilized and determined MXene’s function. Accurate characterization of MXene surface terminations is the prerequisite for studying the regulatory methods and the influence of properties and performance. Because the surface termination of MXene presents two-dimensional plane distribution and the collision probability of atoms, molecules, electrons, and optical signals is low. MXene prepared by chemical methods has certain impurity content. In addition, most surface terminations do not exist in a stable state, which leads to the difficulty of the accurate characterization of MXene surface terminations. At present, XPS, EDX, XAS and EELS are often used for qualitative and quantitative analysis of MXene surface terminations.
  • 1.6K
  • 09 Nov 2022
Topic Review
Characterization of Ti/SnO2 Interface by X-ray Photoelectron Spectroscopy
The Ti/SnO2 interface has been investigated in situ via the technique of x-ray photoelectron spectroscopy. Thin films (in the range from 0.3 to 1.1 nm) of titanium were deposited on SnO2 substrates via the e-beam technique. The deposition was carried out at two different substrate temperatures, namely room temperature and 200 °C. The photoelectron spectra of tin and titanium in the samples were found to exhibit significant differences upon comparison with the corresponding elemental and the oxide spectra. These changes result from chemical interaction between SnO2 and the titanium overlayer at the interface. The SnO2 was observed to be reduced to elemental tin while the titanium overlayer was observed to become oxidized. Complete reduction of SnO2 to elemental tin did not occur even for the lowest thickness of the titanium overlayer. The interfaces in both the types of the samples were observed to consist of elemental Sn, SnO2, elemental titanium, TiO2, and Ti-suboxide. 
  • 597
  • 26 Jan 2022
Topic Review
Charge
In physics, a charge is any of many different quantities, such as the electric charge in electromagnetism or the color charge in quantum chromodynamics. Charges correspond to the time-invariant generators of a symmetry group, and specifically, to the generators that commute with the Hamiltonian. Charges are often denoted by the letter Q, and so the invariance of the charge corresponds to the vanishing commutator [math]\displaystyle{ [Q,H]=0 }[/math], where H is the Hamiltonian. Thus, charges are associated with conserved quantum numbers; these are the eigenvalues q of the generator Q.
  • 547
  • 14 Oct 2022
Topic Review
Charles Hard Townes Medal
The Charles Hard Townes Medal of The Optical Society is a prize for Quantum Electronics — that is to say, the physics of lasers. Awarded annually since 1981, it is named after the Nobel Prize-winning laser pioneer Charles H. Townes. Former winners include Nobel Prize laureates John L. Hall, Claude Cohen-Tannoudji, Serge Haroche, Arthur Ashkin, and Gérard Mourou.
  • 368
  • 25 Oct 2022
Biography
Charles V. Shank
Charles Vernon (Chuck) Shank (born July 12, 1943) is an American physicist, best known as the director of the Lawrence Berkeley National Laboratory from 1989 to 2004. Charles Vernon (Chuck) Shank was born in Mount Holly, New Jersey, on July 12, 1943.[1][2][3] He entered the University of California, Berkeley, where he earned his Bachelor of Science (B.S.) degree in 1965, his Master of Science
  • 573
  • 29 Dec 2022
Topic Review
Chemical Beam Epitaxy
Chemical beam epitaxy (CBE) forms an important class of deposition techniques for semiconductor layer systems, especially III-V semiconductor systems. This form of epitaxial growth is performed in an ultrahigh vacuum system. The reactants are in the form of molecular beams of reactive gases, typically as the hydride or a metalorganic. The term CBE is often used interchangeably with metal-organic molecular beam epitaxy (MOMBE). The nomenclature does differentiate between the two (slightly different) processes, however. When used in the strictest sense, CBE refers to the technique in which both components are obtained from gaseous sources, while MOMBE refers to the technique in which the group III component is obtained from a gaseous source and the group V component from a solid source.
  • 595
  • 30 Nov 2022
Topic Review
Chemical Force Microscopy
In materials science, chemical force microscopy (CFM) is a variation of atomic force microscopy (AFM) which has become a versatile tool for characterization of materials surfaces. With AFM, structural morphology is probed using simple tapping or contact modes that utilize van der Waals interactions between tip and sample to maintain a constant probe deflection amplitude (constant force mode) or maintain height while measuring tip deflection (constant height mode). CFM, on the other hand, uses chemical interactions between functionalized probe tip and sample. Choice chemistry is typically gold-coated tip and surface with R–SH thiols attached, R being the functional groups of interest. CFM enables the ability to determine the chemical nature of surfaces, irrespective of their specific morphology, and facilitates studies of basic chemical bonding enthalpy and surface energy. Typically, CFM is limited by thermal vibrations within the cantilever holding the probe. This limits force measurement resolution to ~1 pN which is still very suitable considering weak COOH/CH3 interactions are ~20 pN per pair. Hydrophobicity is used as the primary example throughout this consideration of CFM, but certainly any type of bonding can be probed with this method.
  • 308
  • 23 Nov 2022
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